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Yin LZ, Luo XQ, Li JL, Liu Z, Duan L, Deng QQ, Chen C, Tang S, Li WJ, Wang P. Deciphering the pathogenic risks of microplastics as emerging particulate organic matter in aquatic ecosystem. JOURNAL OF HAZARDOUS MATERIALS 2024; 474:134728. [PMID: 38805824 DOI: 10.1016/j.jhazmat.2024.134728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 05/07/2024] [Accepted: 05/23/2024] [Indexed: 05/30/2024]
Abstract
Microplastics are accumulating rapidly in aquatic ecosystems, providing habitats for pathogens and vectors for antibiotic resistance genes (ARGs), potentially increasing pathogenic risks. However, few studies have considered microplastics as particulate organic matter (POM) to elucidate their pathogenic risks and underlying mechanisms. Here, we performed microcosm experiments with microplastics and natural POM (leaves, algae, soil), thoroughly investigating their distinct effects on the community compositions, functional profiles, opportunistic pathogens, and ARGs in Particle-Associated (PA) and Free-Living (FL) bacterial communities. We found that both microplastics and leaves have comparable impacts on microbial community structures and functions, enriching opportunistic pathogens and ARGs, which may pose potential environmental risks. These effects are likely driven by their influences on water properties, including dissolved organic carbon, nitrate, DO, and pH. However, microplastics uniquely promoted pathogens as keystone species and further amplified their capacity as hosts for ARGs, potentially posing a higher pathogenic risk than natural POM. Our research also emphasized the importance of considering both PA and FL bacteria when assessing microplastic impacts, as they exhibited different responses. Overall, our study elucidates the role and underlying mechanism of microplastics as an emerging POM in intensifying pathogenic risks of aquatic ecosystems in comparison with conventional natural POM.
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Affiliation(s)
- Ling-Zi Yin
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Ecology & School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China; Bioscience and Biomedical Engineering Thrust, Systems Hub, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, Guangdong, China; Division of Emerging Interdisciplinary Areas, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Xiao-Qing Luo
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Ecology & School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Jia-Ling Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Ecology & School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Zetao Liu
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Ecology & School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Li Duan
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Ecology & School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Qi-Qi Deng
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Ecology & School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Chen Chen
- State Environmental Protection Key Laboratory of Urban Ecological Environment Simulation and Protection, South China Institute of Environmental Sciences, Ministry of Ecology and Environment of China, Guangzhou 510655, China
| | - Shaojun Tang
- Bioscience and Biomedical Engineering Thrust, Systems Hub, The Hong Kong University of Science and Technology (Guangzhou), Guangzhou, Guangdong, China; Division of Emerging Interdisciplinary Areas, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Wen-Jun Li
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Ecology & School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Pandeng Wang
- State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resources and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Ecology & School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
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Şimşek E, Kim K, Lu J, Silver A, Luo N, Lee CT, You L. A 'rich-get-richer' mechanism drives patchy dynamics and resistance evolution in antibiotic-treated bacteria. Mol Syst Biol 2024:10.1038/s44320-024-00046-5. [PMID: 38877321 DOI: 10.1038/s44320-024-00046-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 05/21/2024] [Accepted: 05/23/2024] [Indexed: 06/16/2024] Open
Abstract
Bacteria in nature often form surface-attached communities that initially comprise distinct subpopulations, or patches. For pathogens, these patches can form at infection sites, persist during antibiotic treatment, and develop into mature biofilms. Evidence suggests that patches can emerge due to heterogeneity in the growth environment and bacterial seeding, as well as cell-cell signaling. However, it is unclear how these factors contribute to patch formation and how patch formation might affect bacterial survival and evolution. Here, we demonstrate that a 'rich-get-richer' mechanism drives patch formation in bacteria exhibiting collective survival (CS) during antibiotic treatment. Modeling predicts that the seeding heterogeneity of these bacteria is amplified by local CS and global resource competition, leading to patch formation. Increasing the dose of a non-eradicating antibiotic treatment increases the degree of patchiness. Experimentally, we first demonstrated the mechanism using engineered Escherichia coli and then demonstrated its applicability to a pathogen, Pseudomonas aeruginosa. We further showed that the formation of P. aeruginosa patches promoted the evolution of antibiotic resistance. Our work provides new insights into population dynamics and resistance evolution during surface-attached bacterial growth.
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Affiliation(s)
- Emrah Şimşek
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Center for Quantitative Biodesign, Duke University, Durham, NC, 27708, USA
| | - Kyeri Kim
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Center for Quantitative Biodesign, Duke University, Durham, NC, 27708, USA
| | - Jia Lu
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Center for Quantitative Biodesign, Duke University, Durham, NC, 27708, USA
| | - Anita Silver
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Center for Quantitative Biodesign, Duke University, Durham, NC, 27708, USA
| | - Nan Luo
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 518055, Shenzhen, China
| | - Charlotte T Lee
- Center for Quantitative Biodesign, Duke University, Durham, NC, 27708, USA
- Department of Biology, Duke University, Durham, NC, 27708, USA
| | - Lingchong You
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA.
- Center for Quantitative Biodesign, Duke University, Durham, NC, 27708, USA.
- Center for Genomic and Computational Biology, Duke University, Durham, NC, 27708, USA.
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, 27708, USA.
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3
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Letourneau J, Carrion VM, Jiang S, Osborne OW, Holmes ZC, Fox A, Epstein P, Tan CY, Kirtley M, Surana NK, David LA. Interplay between particle size and microbial ecology in the gut microbiome. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.26.591376. [PMID: 38712077 PMCID: PMC11071529 DOI: 10.1101/2024.04.26.591376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Physical particles can serve as critical abiotic factors that structure the ecology of microbial communities. For non-human vertebrate gut microbiomes, fecal particle size (FPS) has been known to be shaped by chewing efficiency and diet. However, little is known about what drives FPS in the human gut. Here, we analyzed FPS by laser diffraction across a total of 76 individuals and found FPS to be strongly individualized. Surprisingly, a behavioral intervention with 41 volunteers designed to increase chewing efficiency did not impact FPS. Dietary patterns could also not be associated with FPS. Instead, we found evidence that mammalian and human gut microbiomes shaped FPS. Fecal samples from germ-free and antibiotic-treated mice exhibited increased FPS relative to colonized mice. In humans, markers of longer transit time were correlated with smaller FPS. Gut microbiota diversity and composition were also associated with FPS. Finally, ex vivo culture experiments using human fecal microbiota from distinct donors showed that differences in microbiota community composition can drive variation in particle size. Together, our results support an ecological model in which the human gut microbiome plays a key role in reducing the size of food particles during digestion, and that the microbiomes of individuals vary in this capacity. These new insights also suggest FPS in humans to be governed by processes beyond those found in other mammals and emphasize the importance of gut microbiota in shaping their own abiotic environment.
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Affiliation(s)
- Jeffrey Letourneau
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Verónica M Carrion
- Duke Office of Clinical Research, Duke University School of Medicine, Durham, NC 27710
| | - Sharon Jiang
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Olivia W Osborne
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Zachary C Holmes
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Aiden Fox
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Piper Epstein
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Chin Yee Tan
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
- Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710
| | - Michelle Kirtley
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
| | - Neeraj K Surana
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
- Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710
- Department of Integrative Immunobiology, Duke University School of Medicine, Durham, NC 27710
- Duke Microbiome Center, Duke University School of Medicine, Durham, NC 27710
| | - Lawrence A David
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710
- Duke Microbiome Center, Duke University School of Medicine, Durham, NC 27710
- Program in Computational Biology and Bioinformatics, Duke University School of Medicine, Durham, NC 27710
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4
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Brown S, Lloyd CC, Giljan G, Ghobrial S, Amann R, Arnosti C. Pulsed inputs of high molecular weight organic matter shift the mechanisms of substrate utilisation in marine bacterial communities. Environ Microbiol 2024; 26:e16580. [PMID: 38254313 DOI: 10.1111/1462-2920.16580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 12/27/2023] [Indexed: 01/24/2024]
Abstract
Heterotrophic bacteria hydrolyze high molecular weight (HMW) organic matter extracellularly prior to uptake, resulting in diffusive loss of hydrolysis products. An alternative 'selfish' uptake mechanism that minimises this loss has recently been found to be common in the ocean. We investigated how HMW organic matter addition affects these two processing mechanisms in surface and bottom waters at three stations in the North Atlantic Ocean. A pulse of HMW organic matter increased cell numbers, as well as the rate and spectrum of extracellular enzymatic activities at both depths. The effects on selfish uptake were more differentiated: in Gulf Stream surface waters and productive surface waters south of Newfoundland, selfish uptake of structurally simple polysaccharides increased upon HMW organic matter addition. The number of selfish bacteria taking up structurally complex polysaccharides, however, was largely unchanged. In contrast, in the oligotrophic North Atlantic gyre, despite high external hydrolysis rates, the number of selfish bacteria was unchanged, irrespective of polysaccharide structure. In deep bottom waters (> 4000 m), structurally complex substrates were processed only by selfish bacteria. Mechanisms of substrate processing-and the extent to which hydrolysis products are released to the external environment-depend on substrate structural complexity and the resident bacterial community.
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Affiliation(s)
- Sarah Brown
- Environment, Ecology, and Energy Program, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, USA
| | - C Chad Lloyd
- Department of Earth, Marine and Environmental Sciences, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, USA
| | - Greta Giljan
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Sherif Ghobrial
- Department of Earth, Marine and Environmental Sciences, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, USA
| | - Rudolf Amann
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Carol Arnosti
- Department of Earth, Marine and Environmental Sciences, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany
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5
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Rothman DH. Slow closure of Earth's carbon cycle. Proc Natl Acad Sci U S A 2024; 121:e2310998121. [PMID: 38241442 PMCID: PMC10823250 DOI: 10.1073/pnas.2310998121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 12/07/2023] [Indexed: 01/21/2024] Open
Abstract
Carbon near the Earth's surface cycles between the production and consumption of organic carbon; the former sequesters carbon dioxide while the latter releases it. Microbes attempt to close the loop, but the longer organic matter survives, the slower microbial degradation becomes. This aging effect leaves observable quantitative signatures: Organic matter decays at rates that are inversely proportional to its age, while microbial populations and concentrations of organic carbon in ocean sediments decrease at distinct powers of age. Yet mechanisms that predict this collective organization remain unknown. Here, I show that these and other observations follow from the assumption that the decay of organic matter is limited by progressively rare extreme fluctuations in the energy available to microbes for decomposition. The theory successfully predicts not only observed scaling exponents but also a previously unobserved scaling regime that emerges when microbes subsist on the minimum energy flux required for survival. The resulting picture suggests that the carbon cycle's age-dependent dynamics are analogous to the slow approach to equilibrium in disordered systems. The impact of these slow dynamics is profound: They preclude complete oxidation of organic carbon in sediments, thereby freeing molecular oxygen to accumulate in the atmosphere.
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Affiliation(s)
- Daniel H. Rothman
- Lorenz Center, Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA02139
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6
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Stephens BM, Durkin CA, Sharpe G, Nguyen TTH, Albers J, Estapa ML, Steinberg DK, Levine NM, Gifford SM, Carlson CA, Boyd PW, Santoro AE. Direct observations of microbial community succession on sinking marine particles. THE ISME JOURNAL 2024; 18:wrad010. [PMID: 38365233 PMCID: PMC10811735 DOI: 10.1093/ismejo/wrad010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 11/10/2023] [Accepted: 11/15/2023] [Indexed: 02/18/2024]
Abstract
Microbial community dynamics on sinking particles control the amount of carbon that reaches the deep ocean and the length of time that carbon is stored, with potentially profound impacts on Earth's climate. A mechanistic understanding of the controls on sinking particle distributions has been hindered by limited depth- and time-resolved sampling and methods that cannot distinguish individual particles. Here, we analyze microbial communities on nearly 400 individual sinking particles in conjunction with more conventional composite particle samples to determine how particle colonization and community assembly might control carbon sequestration in the deep ocean. We observed community succession with corresponding changes in microbial metabolic potential on the larger sinking particles transporting a significant fraction of carbon to the deep sea. Microbial community richness decreased as particles aged and sank; however, richness increased with particle size and the attenuation of carbon export. This suggests that the theory of island biogeography applies to sinking marine particles. Changes in POC flux attenuation with time and microbial community composition with depth were reproduced in a mechanistic ecosystem model that reflected a range of POC labilities and microbial growth rates. Our results highlight microbial community dynamics and processes on individual sinking particles, the isolation of which is necessary to improve mechanistic models of ocean carbon uptake.
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Affiliation(s)
- Brandon M Stephens
- Department of Ecology, Evolution and Marine Biology, Marine Science Institute, University of California, Santa Barbara, CA 93106, United States
- Present address: Institute of Oceanography, National Taiwan University, Taipei 106, Taiwan
| | - Colleen A Durkin
- Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039, United States
| | - Garrett Sharpe
- Department of Earth, Marine, and Environmental Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
| | - Trang T H Nguyen
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, United States
- Department of Integrated Sciences, Fulbright University Vietnam, Ho Chi Minh City 756000, Vietnam
| | - Justine Albers
- Department of Ecology, Evolution and Marine Biology, Marine Science Institute, University of California, Santa Barbara, CA 93106, United States
| | - Margaret L Estapa
- School of Marine Sciences, Darling Marine Center, University of Maine, Walpole, ME 04573, United States
| | - Deborah K Steinberg
- Coastal & Ocean Processes Section, Virginia Institute of Marine Science, William & Mary, Gloucester Point, VA 23062, United States
| | - Naomi M Levine
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, United States
| | - Scott M Gifford
- Department of Earth, Marine, and Environmental Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
| | - Craig A Carlson
- Department of Ecology, Evolution and Marine Biology, Marine Science Institute, University of California, Santa Barbara, CA 93106, United States
| | - Philip W Boyd
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia
| | - Alyson E Santoro
- Department of Ecology, Evolution and Marine Biology, Marine Science Institute, University of California, Santa Barbara, CA 93106, United States
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7
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Ranheim Sveen T, Hannula SE, Bahram M. Microbial regulation of feedbacks to ecosystem change. Trends Microbiol 2024; 32:68-78. [PMID: 37500365 DOI: 10.1016/j.tim.2023.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 06/12/2023] [Accepted: 06/14/2023] [Indexed: 07/29/2023]
Abstract
Microbes are key biodiversity components of all ecosystems and control vital ecosystem functions. Although we have just begun to unravel the scales and factors that regulate microbial communities, their role in mediating ecosystem stability in response to disturbances remains underexplored. Here, we review evidence of how, when, and where microbes regulate or drive disturbance feedbacks. Negative feedbacks dampen the impacts of disturbance, which maintain ecosystem stability, whereas positive feedbacks instead erode stability by amplifying the disturbance. Here we describe the processes underlying the responses to disturbance using a hierarchy of functional traits, and we exemplify how these may drive biogeochemical feedbacks. We suggest that the feedback potential of functional traits at different hierarchical levels is contingent on the complexity and heterogeneity of the environment.
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Affiliation(s)
- T Ranheim Sveen
- Department of Ecology, Swedish University of Agricultural Sciences, Ulls Väg 16, 756 51 Uppsala, Sweden.
| | - S E Hannula
- Institute of Environmental Sciences, Leiden University, Leiden 2333, The Netherlands
| | - M Bahram
- Department of Ecology, Swedish University of Agricultural Sciences, Ulls Väg 16, 756 51 Uppsala, Sweden; Institute of Ecology and Earth Sciences, University of Tartu, Tartu, Estonia
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8
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Pavia MJ, Finn D, Macedo-Tafur F, Tello-Espinoza R, Penaccio C, Bouskill N, Cadillo-Quiroz H. Genes and genome-resolved metagenomics reveal the microbial functional make up of Amazon peatlands under geochemical gradients. Environ Microbiol 2023; 25:2388-2403. [PMID: 37501535 DOI: 10.1111/1462-2920.16469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 07/12/2023] [Indexed: 07/29/2023]
Abstract
The Pastaza-Marañón Foreland Basin (PMFB) holds the most extensive tropical peatland area in South America. PMFB peatlands store ~7.07 Gt of organic carbon interacting with multiple microbial heterotrophic, methanogenic, and other aerobic/anaerobic respirations. Little is understood about the contribution of distinct microbial community members inhabiting tropical peatlands. Here, we studied the metagenomes of three geochemically distinct peatlands spanning minerotrophic, mixed, and ombrotrophic conditions. Using gene- and genome-centric approaches, we evaluate the functional potential of the underlying microbial communities. Abundance analyses show significant differences in C, N, P, and S acquisition genes. Furthermore, community interactions mediated by toxin-antitoxin and CRISPR-Cas systems were enriched in oligotrophic soils, suggesting that non-metabolic interactions may exert additional controls in low-nutrient environments. Additionally, we reconstructed 519 metagenome-assembled genomes spanning 28 phyla. Our analyses detail key differences across the geochemical gradient in the predicted microbial populations involved in degradation of organic matter, and the cycling of N and S. Notably, we observed differences in the nitric oxide (NO) reduction strategies between sites with high and low N2 O fluxes and found phyla putatively capable of both NO and sulfate reduction. Our findings detail how gene abundances and microbial populations are influenced by geochemical differences in tropical peatlands.
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Affiliation(s)
- Michael J Pavia
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, Arizona, USA
| | - Damien Finn
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
| | - Franco Macedo-Tafur
- Laboratory of Soil Research, Research Institute of Amazonia's Natural Resources, National University of the Peruvian Amazon, Iquitos, Loreto, Peru
| | - Rodil Tello-Espinoza
- Laboratory of Soil Research, Research Institute of Amazonia's Natural Resources, National University of the Peruvian Amazon, Iquitos, Loreto, Peru
- School of Forestry, National University of the Peruvian Amazon, Iquitos, Loreto, Peru
| | - Christa Penaccio
- Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Nicholas Bouskill
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Hinsby Cadillo-Quiroz
- School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University, Tempe, Arizona, USA
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9
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D’Souza G, Schwartzman J, Keegstra J, Schreier JE, Daniels M, Cordero OX, Stocker R, Ackermann M. Interspecies interactions determine growth dynamics of biopolymer-degrading populations in microbial communities. Proc Natl Acad Sci U S A 2023; 120:e2305198120. [PMID: 37878716 PMCID: PMC10622921 DOI: 10.1073/pnas.2305198120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 09/12/2023] [Indexed: 10/27/2023] Open
Abstract
Microbial communities perform essential ecosystem functions such as the remineralization of organic carbon that exists as biopolymers. The first step in mineralization is performed by biopolymer degraders, which harbor enzymes that can break down polymers into constituent oligo- or monomeric forms. The released nutrients not only allow degraders to grow, but also promote growth of cells that either consume the degradation products, i.e., exploiters, or consume metabolites released by the degraders or exploiters, i.e., scavengers. It is currently not clear how such remineralizing communities assemble at the microscale-how interactions between the different guilds influence their growth and spatial distribution, and hence the development and dynamics of the community. Here, we address this knowledge gap by studying marine microbial communities that grow on the abundant marine biopolymer alginate. We used batch growth assays and microfluidics coupled to time-lapse microscopy to quantitatively investigate growth and spatial distribution of single cells. We found that the presence of exploiters or scavengers alters the spatial distribution of degrader cells. In general, exploiters and scavengers-which we collectively refer to as cross-feeder cells-slowed down the growth of degrader cells. In addition, coexistence with cross-feeders altered the production of the extracellular enzymes that break down polymers by degrader cells. Our findings reveal that ecological interactions by nondegrading community members have a profound impact on the functions of microbial communities that remineralize carbon biopolymers in nature.
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Affiliation(s)
- Glen D’Souza
- Microbial Systems Ecology Group, Department of Environmental Systems Sciences, Institute of Biogeochemistry and Pollutant Dynamics, ETH-Zurich, Zurich8006, Switzerland
- Department of Environmental Microbiology, Eawag: Swiss Federal Institute of Aquatic Sciences, Duebendorf8600, Switzerland
| | - Julia Schwartzman
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Johannes Keegstra
- Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zurich, Zurich8093, Switzerland
| | | | - Michael Daniels
- Microbial Systems Ecology Group, Department of Environmental Systems Sciences, Institute of Biogeochemistry and Pollutant Dynamics, ETH-Zurich, Zurich8006, Switzerland
- Department of Environmental Microbiology, Eawag: Swiss Federal Institute of Aquatic Sciences, Duebendorf8600, Switzerland
| | - Otto X. Cordero
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Roman Stocker
- Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zurich, Zurich8093, Switzerland
| | - Martin Ackermann
- Microbial Systems Ecology Group, Department of Environmental Systems Sciences, Institute of Biogeochemistry and Pollutant Dynamics, ETH-Zurich, Zurich8006, Switzerland
- Department of Environmental Microbiology, Eawag: Swiss Federal Institute of Aquatic Sciences, Duebendorf8600, Switzerland
- Environmental Engineering Institute, School of Architecture, Civil and Environmental Engineering, École polytechnique fédérale de Lausanne, CH-1015Lausanne, Switzerland
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10
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Pompei S, Bella E, Weitz JS, Grilli J, Lagomarsino MC. Metacommunity structure preserves genome diversity in the presence of gene-specific selective sweeps under moderate rates of horizontal gene transfer. PLoS Comput Biol 2023; 19:e1011532. [PMID: 37792894 PMCID: PMC10578598 DOI: 10.1371/journal.pcbi.1011532] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 10/16/2023] [Accepted: 09/19/2023] [Indexed: 10/06/2023] Open
Abstract
The horizontal transfer of genes is fundamental for the eco-evolutionary dynamics of microbial communities, such as oceanic plankton, soil, and the human microbiome. In the case of an acquired beneficial gene, classic population genetics would predict a genome-wide selective sweep, whereby the genome spreads clonally within the community and together with the beneficial gene, removing genome diversity. Instead, several sources of metagenomic data show the existence of "gene-specific sweeps", whereby a beneficial gene spreads across a bacterial community, maintaining genome diversity. Several hypotheses have been proposed to explain this process, including the decreasing gene flow between ecologically distant populations, frequency-dependent selection from linked deleterious allelles, and very high rates of horizontal gene transfer. Here, we propose an additional possible scenario grounded in eco-evolutionary principles. Specifically, we show by a mathematical model and simulations that a metacommunity where species can occupy multiple patches, acting together with a realistic (moderate) HGT rate, helps maintain genome diversity. Assuming a scenario of patches dominated by single species, our model predicts that diversity only decreases moderately upon the arrival of a new beneficial gene, and that losses in diversity can be quickly restored. We explore the generic behaviour of diversity as a function of three key parameters, frequency of insertion of new beneficial genes, migration rates and horizontal transfer rates.Our results provides a testable explanation for how diversity can be maintained by gene-specific sweeps even in the absence of high horizontal gene transfer rates.
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Affiliation(s)
- Simone Pompei
- IFOM ETS - The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Edoardo Bella
- Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16 Milano, Italy
| | - Joshua S. Weitz
- Department of Biology, University of Maryland, College Park, Maryland, United States of America
- Department of Physics, University of Maryland, College Park, Maryland, United States of America
- Institut de Biologie, École Normale Supérieure, Paris, France
| | - Jacopo Grilli
- Quantitative Life Sciences, The Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy
| | - Marco Cosentino Lagomarsino
- IFOM ETS - The AIRC Institute of Molecular Oncology, Milan, Italy
- Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16 Milano, Italy
- I.N.F.N, via Celoria 16 Milano, Italy
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11
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Abed RMM, Al-Hinai M, Al-Balushi Y, Haider L, Muthukrishnan T, Rinner U. Degradation of starch-based bioplastic bags in the pelagic and benthic zones of the Gulf of Oman. MARINE POLLUTION BULLETIN 2023; 195:115496. [PMID: 37703633 DOI: 10.1016/j.marpolbul.2023.115496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 08/21/2023] [Accepted: 09/02/2023] [Indexed: 09/15/2023]
Abstract
The Gulf of Oman is becoming increasingly polluted with plastics, hence bioplastics have been considered 'a substitute', although their biodegradability in marine environments has not been well investigated. Most research has been performed on cellulose-based bioplastics, whereas starch-based bioplastics have proven to be a suitable, but less researched, alternative. This study is the first of its kind designed to investigate the degradability of two different types of starch-based bioplastic bags, available in the market and labeled as "biodegradable", in the pelagic and benthic zones of one of the warmest marine environment in the world. Fourier-Transform Infrared Spectroscopy (FTIR) showed a clear reduction in the presence of OH, CH, and CO in the bioplastic bags after 5 weeks of immersion. Thermo-Gravimetric Analysis (TGA) indicated degradation of glycerol, starch, and polyethylene. The biofouling bacterial communities on bioplastic surfaces showed distinct grouping based on the immersion zone. Candidaatus saccharibacteria, Verrucomicrobiae, Acidimicrobiia and Planctomycetia sequences were only detectable on bioplastics in the pelagic zone, whereas Actinomyces, Pseudomonas, Sphingobium and Acinetobacter related sequences were only found on bioplastics in the benthic layer. We conclude that starch-based bioplastics are more readily degradable in the Gulf of Oman than conventional plastics, hence could serve as a better environmentally friendly alternative.
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Affiliation(s)
- Raeid M M Abed
- Biology Department, College of Science, Sultan Qaboos University, P. O. Box: 36, PC 123 Al Khoud, Sultanate of Oman.
| | - Mahmood Al-Hinai
- Biology Department, College of Science, Sultan Qaboos University, P. O. Box: 36, PC 123 Al Khoud, Sultanate of Oman
| | - Yasmin Al-Balushi
- Biology Department, College of Science, Sultan Qaboos University, P. O. Box: 36, PC 123 Al Khoud, Sultanate of Oman
| | - Lorenz Haider
- Institute of Applied Chemistry, IMC University of Applied Sciences Krems, Piaristengasse 1, 3500 Krems, Austria
| | - Thirumahal Muthukrishnan
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Ontario M5S 3E5, Canada
| | - Uwe Rinner
- Institute of Applied Chemistry, IMC University of Applied Sciences Krems, Piaristengasse 1, 3500 Krems, Austria
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12
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Yao T, Deemer DG, Chen MH, Reuhs BL, Hamaker BR, Lindemann SR. Differences in fine arabinoxylan structures govern microbial selection and competition among human gut microbiota. Carbohydr Polym 2023; 316:121039. [PMID: 37321733 DOI: 10.1016/j.carbpol.2023.121039] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/27/2023] [Accepted: 05/18/2023] [Indexed: 06/17/2023]
Abstract
Dietary fibers are known to modulate microbiome composition, but it is unclear to what extent minor fiber structural differences impact community assembly, microbial division of labor, and organismal metabolic responses. To test the hypothesis that fine linkage variations afford different ecological niches for distinct communities and metabolism, we employed a 7-day in vitro sequential batch fecal fermentation with four fecal inocula and measured responses using an integrated multi-omics approach. Two sorghum arabinoxylans (SAXs) were fermented, with one (RSAX) having slightly more complex branch linkages than the other (WSAX). Although there were minor glycoysl linkage differences, consortia on RSAX retained much higher species diversity (42 members) than on WSAX (18-23 members) with distinct species-level genomes and metabolic outcomes (e.g., higher short chain fatty acid production from RSAX and more lactic acid produced from WSAX). The major SAX-selected members were from genera of Bacteroides and Bifidobacterium and family Lachnospiraceae. Carbohydrate active enzyme (CAZyme) genes in metagenomes revealed broad AX-related hydrolytic potentials among key members; however, CAZyme genes enriched in different consortia displayed various catabolic domain fusions with diverse accessory motifs that differ among the two SAX types. These results suggest that fine polysaccharide structure exerts deterministic selection effect for distinct fermenting consortia.
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Affiliation(s)
- Tianming Yao
- Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA
| | - Dane G Deemer
- Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA
| | - Ming-Hsu Chen
- Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA; Institute of Food Science and Technology of National Taiwan University. No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Bradley L Reuhs
- Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA
| | - Bruce R Hamaker
- Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA
| | - Stephen R Lindemann
- Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA.
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13
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Hockenberry A, Slack E, Stadtmueller BM. License to Clump: Secretory IgA Structure-Function Relationships Across Scales. Annu Rev Microbiol 2023; 77:645-668. [PMID: 37713459 DOI: 10.1146/annurev-micro-032521-041803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
Secretory antibodies are the only component of our adaptive immune system capable of attacking mucosal pathogens topologically outside of our bodies. All secretory antibody classes are (a) relatively resistant to harsh proteolytic environments and (b) polymeric. Recent elucidation of the structure of secretory IgA (SIgA) has begun to shed light on SIgA functions at the nanoscale. We can now begin to unravel the structure-function relationships of these molecules, for example, by understanding how the bent conformation of SIgA enables robust cross-linking between adjacent growing bacteria. Many mysteries remain, such as the structural basis of protease resistance and the role of noncanonical bacteria-IgA interactions. In this review, we explore the structure-function relationships of IgA from the nano- to the metascale, with a strong focus on how the seemingly banal "license to clump" can have potent effects on bacterial physiology and colonization.
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Affiliation(s)
- Alyson Hockenberry
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Dübendorf, Switzerland
- Department of Environmental Systems Science (D-USYS), ETH Zürich, Zürich, Switzerland;
| | - Emma Slack
- Department of Health Sciences and Technology, ETH Zürich, Zürich, Switzerland;
- Botnar Research Centre for Child Health, Basel, Switzerland
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Beth M Stadtmueller
- Department of Biochemistry, Center for Biophysics and Quantitative Biology, and Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois, USA;
- Department of Biomedical and Translational Sciences, Carle Illinois College of Medicine, University of Illinois, Urbana, Illinois, USA
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14
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Rosazza T, Eigentler L, Earl C, Davidson FA, Stanley‐Wall NR. Bacillus subtilis extracellular protease production incurs a context-dependent cost. Mol Microbiol 2023; 120:105-121. [PMID: 37380434 PMCID: PMC10952608 DOI: 10.1111/mmi.15110] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 06/07/2023] [Accepted: 06/08/2023] [Indexed: 06/30/2023]
Abstract
Microbes encounter a wide range of polymeric nutrient sources in various environmental settings, which require processing to facilitate growth. Bacillus subtilis, a bacterium found in the rhizosphere and broader soil environment, is highly adaptable and resilient due to its ability to utilise diverse sources of carbon and nitrogen. Here, we explore the role of extracellular proteases in supporting growth and assess the cost associated with their production. We provide evidence of the essentiality of extracellular proteases when B. subtilis is provided with an abundant, but polymeric nutrient source and demonstrate the extracellular proteases as a shared public good that can operate over a distance. We show that B. subtilis is subjected to a public good dilemma, specifically in the context of growth sustained by the digestion of a polymeric food source. Furthermore, using mathematical simulations, we uncover that this selectively enforced dilemma is driven by the relative cost of producing the public good. Collectively, our findings reveal how bacteria can survive in environments that vary in terms of immediate nutrient accessibility and the consequent impact on the population composition. These findings enhance our fundamental understanding of how bacteria respond to diverse environments, which has importance to contexts ranging from survival in the soil to infection and pathogenesis scenarios.
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Affiliation(s)
- Thibault Rosazza
- Division of Molecular Microbiology, School of Life ScienceUniversity of DundeeDundeeUK
| | - Lukas Eigentler
- Division of Molecular Microbiology, School of Life ScienceUniversity of DundeeDundeeUK
- Mathematics, School of Science and EngineeringUniversity of DundeeDundeeUK
- Present address:
Evolutionary Biology DepartmentUniversität BielefeldKonsequenz 45Bielefeld33615Germany
| | - Chris Earl
- Division of Molecular Microbiology, School of Life ScienceUniversity of DundeeDundeeUK
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15
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Sun CC, Zhao WJ, Yue WZ, Cheng H, Sun FL, Wang YT, Wu ML, Engel A, Wang YS. Polymeric carbohydrates utilization separates microbiomes into niches: insights into the diversity of microbial carbohydrate-active enzymes in the inner shelf of the Pearl River Estuary, China. Front Microbiol 2023; 14:1180321. [PMID: 37425997 PMCID: PMC10322874 DOI: 10.3389/fmicb.2023.1180321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 05/31/2023] [Indexed: 07/11/2023] Open
Abstract
Polymeric carbohydrates are abundant and their recycling by microbes is a key process of the ocean carbon cycle. A deeper analysis of carbohydrate-active enzymes (CAZymes) can offer a window into the mechanisms of microbial communities to degrade carbohydrates in the ocean. In this study, metagenomic genes encoding microbial CAZymes and sugar transporter systems were predicted to assess the microbial glycan niches and functional potentials of glycan utilization in the inner shelf of the Pearl River Estuary (PRE). The CAZymes gene compositions were significantly different between in free-living (0.2-3 μm, FL) and particle-associated (>3 μm, PA) bacteria of the water column and between water and surface sediments, reflecting glycan niche separation on size fraction and selective degradation in depth. Proteobacteria and Bacteroidota had the highest abundance and glycan niche width of CAZymes genes, respectively. At the genus level, Alteromonas (Gammaproteobacteria) exhibited the greatest abundance and glycan niche width of CAZymes genes and were marked by a high abundance of periplasmic transporter protein TonB and members of the major facilitator superfamily (MFS). The increasing contribution of genes encoding CAZymes and transporters for Alteromonas in bottom water contrasted to surface water and their metabolism are tightly related with particulate carbohydrates (pectin, alginate, starch, lignin-cellulose, chitin, and peptidoglycan) rather than on the utilization of ambient-water DOC. Candidatus Pelagibacter (Alphaproteobacteria) had a narrow glycan niche and was primarily preferred for nitrogen-containing carbohydrates, while their abundant sugar ABC (ATP binding cassette) transporter supported the scavenging mode for carbohydrate assimilation. Planctomycetota, Verrucomicrobiota, and Bacteroidota had similar potential glycan niches in the consumption of the main component of transparent exopolymer particles (sulfated fucose and rhamnose containing polysaccharide and sulfated-N-glycan), developing considerable niche overlap among these taxa. The most abundant CAZymes and transporter genes as well as the widest glycan niche in the abundant bacterial taxa implied their potential key roles on the organic carbon utilization, and the high degree of glycan niches separation and polysaccharide composition importantly influenced bacterial communities in the coastal waters of PRE. These findings expand the current understanding of the organic carbon biotransformation, underlying the size-fractionated glycan niche separation near the estuarine system.
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Affiliation(s)
- Cui-Ci Sun
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Daya Bay Marine Biology Research Station, Chinese Academy of Sciences, Shenzhen, China
| | - Wen-Jie Zhao
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Wei-Zhong Yue
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Hao Cheng
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Fu-Lin Sun
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Daya Bay Marine Biology Research Station, Chinese Academy of Sciences, Shenzhen, China
| | - Yu-Tu Wang
- Daya Bay Marine Biology Research Station, Chinese Academy of Sciences, Shenzhen, China
| | - Mei-Lin Wu
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Anja Engel
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - You-Shao Wang
- State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Daya Bay Marine Biology Research Station, Chinese Academy of Sciences, Shenzhen, China
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16
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Dithugoe CD, Bezuidt OKI, Cavan EL, Froneman WP, Thomalla SJ, Makhalanyane TP. Bacteria and Archaea Regulate Particulate Organic Matter Export in Suspended and Sinking Marine Particle Fractions. mSphere 2023:e0042022. [PMID: 37093039 DOI: 10.1128/msphere.00420-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023] Open
Abstract
The biological carbon pump (BCP) in the Southern Ocean is driven by phytoplankton productivity and is a significant organic matter sink. However, the role of particle-attached (PA) and free-living (FL) prokaryotes (bacteria and archaea) and their diversity in influencing the efficiency of the BCP is still unclear. To investigate this, we analyzed the metagenomes linked to suspended and sinking marine particles from the Sub-Antarctic Southern Ocean Time Series (SOTS) by deploying a Marine Snow Catcher (MSC), obtaining suspended and sinking particulate material, determining organic carbon and nitrogen flux, and constructing metagenome-assembled genomes (MAGs). The suspended and sinking particle-pools were dominated by bacteria with the potential to degrade organic carbon. Bacterial communities associated with the sinking fraction had more genes related to the degradation of complex organic carbon than those in the suspended fraction. Archaea had the potential to drive nitrogen metabolism via nitrite and ammonia oxidation, altering organic nitrogen concentration. The data revealed several pathways for chemoautotrophy and the secretion of recalcitrant dissolved organic carbon (RDOC) from CO2, with bacteria and archaea potentially sequestering particulate organic matter (POM) via the production of RDOC. These findings provide insights into the diversity and function of prokaryotes in suspended and sinking particles and their role in organic carbon/nitrogen export in the Southern Ocean. IMPORTANCE The biological carbon pump is crucial for the export of particulate organic matter in the ocean. Recent studies on marine microbes have shown the profound influence of bacteria and archaea as regulators of particulate organic matter export. Yet, despite the importance of the Southern Ocean as a carbon sink, we lack comparable insights regarding microbial contributions. This study provides the first insights regarding prokaryotic contributions to particulate organic matter export in the Southern Ocean. We reveal evidence that prokaryotic communities in suspended and sinking particle fractions harbor widespread genomic potential for mediating particulate organic matter export. The results substantially enhance our understanding of the role played by microorganisms in regulating particulate organic matter export in suspended and sinking marine fractions in the Southern Ocean.
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Affiliation(s)
- Choaro D Dithugoe
- Southern Ocean Carbon-Climate Observatory (SOCCO), Council of Scientific & Industrial Research (CSIR), Rosebank, Cape Town, South Africa
- SARChI Chair: Marine Ecosystems and Resources, Department of Entomology & Zoology, Rhodes University (RU), Makhanda, Eastern Cape, South Africa
- SARChI Chair: Marine Microbiomics, microbiome@UP, Department of Biochemistry, Genetics and Microbiology, University of Pretoria (UP), Hatfield, Pretoria, South Africa
| | - Oliver K I Bezuidt
- SARChI Chair: Marine Microbiomics, microbiome@UP, Department of Biochemistry, Genetics and Microbiology, University of Pretoria (UP), Hatfield, Pretoria, South Africa
| | - Emma L Cavan
- Imperial College London, Berks, Silwood Park, Berkshire, United Kingdom
| | - William P Froneman
- SARChI Chair: Marine Ecosystems and Resources, Department of Entomology & Zoology, Rhodes University (RU), Makhanda, Eastern Cape, South Africa
| | - Sandy J Thomalla
- Southern Ocean Carbon-Climate Observatory (SOCCO), Council of Scientific & Industrial Research (CSIR), Rosebank, Cape Town, South Africa
| | - Thulani P Makhalanyane
- SARChI Chair: Marine Microbiomics, microbiome@UP, Department of Biochemistry, Genetics and Microbiology, University of Pretoria (UP), Hatfield, Pretoria, South Africa
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17
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Cell aggregation is associated with enzyme secretion strategies in marine polysaccharide-degrading bacteria. THE ISME JOURNAL 2023; 17:703-711. [PMID: 36813911 PMCID: PMC10119383 DOI: 10.1038/s41396-023-01385-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 02/06/2023] [Accepted: 02/13/2023] [Indexed: 02/24/2023]
Abstract
Polysaccharide breakdown by bacteria requires the activity of enzymes that degrade polymers either intra- or extra-cellularly. The latter mechanism generates a localized pool of breakdown products that are accessible to the enzyme producers themselves as well as to other organisms. Marine bacterial taxa often show marked differences in the production and secretion of degradative enzymes that break down polysaccharides. These differences can have profound effects on the pool of diffusible breakdown products and hence on the ecological dynamics. However, the consequences of differences in enzymatic secretions on cellular growth dynamics and interactions are unclear. Here we study growth dynamics of single cells within populations of marine Vibrionaceae strains that grow on the abundant marine polymer alginate, using microfluidics coupled to quantitative single-cell analysis and mathematical modelling. We find that strains that have low extracellular secretions of alginate lyases aggregate more strongly than strains that secrete high levels of enzymes. One plausible reason for this observation is that low secretors require a higher cellular density to achieve maximal growth rates in comparison with high secretors. Our findings indicate that increased aggregation increases intercellular synergy amongst cells of low-secreting strains. By mathematically modelling the impact of the level of degradative enzyme secretion on the rate of diffusive oligomer loss, we find that enzymatic secretion capability modulates the propensity of cells within clonal populations to cooperate or compete with each other. Our experiments and models demonstrate that enzymatic secretion capabilities can be linked with the propensity of cell aggregation in marine bacteria that extracellularly catabolize polysaccharides.
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18
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Breakdown of clonal cooperative architecture in multispecies biofilms and the spatial ecology of predation. Proc Natl Acad Sci U S A 2023; 120:e2212650120. [PMID: 36730197 PMCID: PMC9963355 DOI: 10.1073/pnas.2212650120] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Biofilm formation, including adherence to surfaces and secretion of extracellular matrix, is common in the microbial world, but we often do not know how interaction at the cellular spatial scale translates to higher-order biofilm community ecology. Here we explore an especially understudied element of biofilm ecology, namely predation by the bacterium Bdellovibrio bacteriovorus. This predator can kill and consume many different Gram-negative bacteria, including Vibrio cholerae and Escherichia coli. V. cholerae can protect itself from predation within densely packed biofilm structures that it creates, whereas E. coli biofilms are highly susceptible to B. bacteriovorus. We explore how predator-prey dynamics change when V. cholerae and E. coli are growing in biofilms together. We find that in dual-species prey biofilms, E. coli survival under B. bacteriovorus predation increases, whereas V. cholerae survival decreases. E. coli benefits from predator protection when it becomes embedded within expanding groups of highly packed V. cholerae. But we also find that the ordered, highly packed, and clonal biofilm structure of V. cholerae can be disrupted if V. cholerae cells are directly adjacent to E. coli cells at the start of biofilm growth. When this occurs, the two species become intermixed, and the resulting disordered cell groups do not block predator entry. Because biofilm cell group structure depends on initial cell distributions at the start of prey biofilm growth, the surface colonization dynamics have a dramatic impact on the eventual multispecies biofilm architecture, which in turn determines to what extent both species survive exposure to B. bacteriovorus.
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19
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Giljan G, Brown S, Lloyd CC, Ghobrial S, Amann R, Arnosti C. Selfish bacteria are active throughout the water column of the ocean. ISME COMMUNICATIONS 2023; 3:11. [PMID: 36739317 PMCID: PMC9899235 DOI: 10.1038/s43705-023-00219-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/22/2023] [Accepted: 01/26/2023] [Indexed: 02/06/2023]
Abstract
Heterotrophic bacteria in the ocean invest carbon, nitrogen, and energy in extracellular enzymes to hydrolyze large substrates to smaller sizes suitable for uptake. Since hydrolysis products produced outside of a cell may be lost to diffusion, the return on this investment is uncertain. Selfish bacteria change the odds in their favor by binding, partially hydrolyzing, and transporting polysaccharides into the periplasmic space without loss of hydrolysis products. We expected selfish bacteria to be most common in the upper ocean, where phytoplankton produce abundant fresh organic matter, including complex polysaccharides. We, therefore, sampled water in the western North Atlantic Ocean at four depths from three stations differing in physiochemical conditions; these stations and depths also differed considerably in microbial community composition. To our surprise, we found that selfish bacteria are common throughout the water column of the ocean, including at depths greater than 5500 m. Selfish uptake as a strategy thus appears to be geographically-and phylogenetically-widespread. Since processing and uptake of polysaccharides require enzymes that are highly sensitive to substrate structure, the activities of these bacteria might not be reflected by measurements relying on uptake only of low molecular weight substrates. Moreover, even at the bottom of the ocean, the supply of structurally-intact polysaccharides, and therefore the return on enzymatic investment, must be sufficient to maintain these organisms.
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Affiliation(s)
- Greta Giljan
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Sarah Brown
- Environment, Ecology, and Energy Program, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
| | - C Chad Lloyd
- Department of Earth, Marine, and Environmental Sciences, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
| | - Sherif Ghobrial
- Department of Earth, Marine, and Environmental Sciences, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA
| | - Rudolf Amann
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Carol Arnosti
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany.
- Department of Earth, Marine, and Environmental Sciences, University of North Carolina-Chapel Hill, Chapel Hill, NC, USA.
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20
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Yu F, Zhang W, Hou X, Li Y, Tong J. How nutrient loads influence microbial-derived carbon accumulation in wetlands: A new insight from microbial metabolic investment strategies. ENVIRONMENTAL RESEARCH 2023; 217:114981. [PMID: 36460070 DOI: 10.1016/j.envres.2022.114981] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/13/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Excessive anthropogenic nutrient inputs often lead to the degradation of wetland ecosystems and a decrease in carbon sink capacity. Microbial-derived carbon is increasingly recognized as an important precursor for organic carbon formation, which is controlled by the balance between microbial anabolic and catabolic processes. Shifts in microbial metabolic investment under nutrient load disturbance are key, but understudied, components of microbial-derived carbon turnover. Here, the roles of the distinct life-history traits and cooperation degree of key microbial assemblies in regulating microbial-derived carbon accumulation in a wetland receiving treated wastewater were firstly assessed by combining microbial biomarkers and genomic approaches. It was found that microbial-derived carbon was an important source of organic carbon in wetlands, and strongly associated with several microbial assemblies with specific trait strategies. Further analysis demonstrated that high growth yield strategists were mainly associated with microbial necromass accrual, while microbial biomass was more dominated by resource acquisition strategies in nutrient-imbalanced wetlands. A significant positive relationship between positive cohesion and microbial-derived carbon indicated that cooperative behavior among taxa promoted the production and accumulation of microbial-derived carbon. Moreover, resource stoichiometric balance, including C:N and C:P, was identified as an important driver of shifts in microbial metabolic investment strategies. The decreased C:N ratio led to a shift from resource acquisition strategies to high growth yield strategies for the microbial community, which facilitated microbial necromass accrual along the N-limited wetland, while the increased C:P ratio caused by excessive P deposition in sediments limits microbial cooperative growth to some extent. This study highlighted the importance of stoichiometric balance in mediating microbial growth metabolism and, in turn, enhancing the carbon sink capacity of wetlands.
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Affiliation(s)
- Feng Yu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, PR China
| | - Wenlong Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, PR China.
| | - Xing Hou
- Institute of Water Science and Technology, Hohai University, Nanjing, 210098, PR China
| | - Yi Li
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, PR China.
| | - Jiaxin Tong
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, 210098, PR China
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21
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Arandia-Gorostidi N, Parada AE, Dekas AE. Single-cell view of deep-sea microbial activity and intracommunity heterogeneity. THE ISME JOURNAL 2023; 17:59-69. [PMID: 36202927 PMCID: PMC9750969 DOI: 10.1038/s41396-022-01324-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 09/08/2022] [Accepted: 09/12/2022] [Indexed: 12/15/2022]
Abstract
Microbial activity in the deep sea is cumulatively important for global elemental cycling yet is difficult to quantify and characterize due to low cell density and slow growth. Here, we investigated microbial activity off the California coast, 50-4000 m water depth, using sensitive single-cell measurements of stable-isotope uptake and nucleic acid sequencing. We observed the highest yet reported proportion of active cells in the bathypelagic (up to 78%) and calculated that deep-sea cells (200-4000 m) are responsible for up to 34% of total microbial biomass synthesis in the water column. More cells assimilated nitrogen derived from amino acids than ammonium, and at higher rates. Nitrogen was assimilated preferentially to carbon from amino acids in surface waters, while the reverse was true at depth. We introduce and apply the Gini coefficient, an established equality metric in economics, to quantify intracommunity heterogeneity in microbial anabolic activity. We found that heterogeneity increased with water depth, suggesting a minority of cells contribute disproportionately to total activity in the deep sea. This observation was supported by higher RNA/DNA ratios for low abundance taxa at depth. Intracommunity activity heterogeneity is a fundamental and rarely measured ecosystem parameter and may have implications for community function and resilience.
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Affiliation(s)
| | - A E Parada
- Department of Earth System Science, Stanford University, Stanford, CA, USA
| | - A E Dekas
- Department of Earth System Science, Stanford University, Stanford, CA, USA.
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22
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Borer B, Zhang IH, Baker AE, O'Toole GA, Babbin AR. Porous marine snow differentially benefits chemotactic, motile, and nonmotile bacteria. PNAS NEXUS 2022; 2:pgac311. [PMID: 36845354 PMCID: PMC9944246 DOI: 10.1093/pnasnexus/pgac311] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 12/23/2022] [Indexed: 12/28/2022]
Abstract
Particulate organic carbon settling through the marine water column is a key process that regulates the global climate by sequestering atmospheric carbon. The initial colonization of marine particles by heterotrophic bacteria represents the first step in recycling this carbon back to inorganic constituents-setting the magnitude of vertical carbon transport to the abyss. Here, we demonstrate experimentally using millifluidic devices that, although bacterial motility is essential for effective colonization of a particle leaking organic nutrients into the water column, chemotaxis specifically benefits at intermediate and higher settling velocities to navigate the particle boundary layer during the brief window of opportunity provided by a passing particle. We develop an individual-based model that simulates the encounter and attachment of bacterial cells with leaking marine particles to systematically evaluate the role of different parameters associated with bacterial run-and-tumble motility. We further use this model to explore the role of particle microstructure on the colonization efficiency of bacteria with different motility traits. We find that the porous microstructure facilitates additional colonization by chemotactic and motile bacteria, and fundamentally alters the way nonmotile cells interact with particles due to streamlines intersecting with the particle surface.
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Affiliation(s)
| | - Irene H Zhang
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology Cambridge, Cambridge, MA 02139, USA
| | - Amy E Baker
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - George A O'Toole
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
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23
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Iven H, Walker TWN, Anthony M. Biotic Interactions in Soil are Underestimated Drivers of Microbial Carbon Use Efficiency. Curr Microbiol 2022; 80:13. [PMID: 36459292 PMCID: PMC9718865 DOI: 10.1007/s00284-022-02979-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 04/05/2022] [Indexed: 12/05/2022]
Abstract
Microbial carbon use efficiency (CUE)-the balance between microbial growth and respiration-strongly impacts microbial mediated soil carbon storage and is sensitive to many well-studied abiotic environmental factors. However, surprisingly, little work has examined how biotic interactions in soil may impact CUE. Here, we review the theoretical and empirical lines of evidence exploring how biotic interactions affect CUE through the lens of life history strategies. Fundamentally, the CUE of a microbial population is constrained by population density and carrying capacity, which, when reached, causes species to grow more quickly and less efficiently. When microbes engage in interspecific competition, they accelerate growth rates to acquire limited resources and release secondary chemicals toxic to competitors. Such processes are not anabolic and thus constrain CUE. In turn, antagonists may activate one of a number of stress responses that also do not involve biomass production, potentially further reducing CUE. In contrast, facilitation can increase CUE by expanding species realized niches, mitigating environmental stress and reducing production costs of extracellular enzymes. Microbial interactions at higher trophic levels also influence CUE. For instance, predation on microbes can positively or negatively impact CUE by changing microbial density and the outcomes of interspecific competition. Finally, we discuss how plants select for more or less efficient microbes under different contexts. In short, this review demonstrates the potential for biotic interactions to be a strong regulator of microbial CUE and additionally provides a blueprint for future research to address key knowledge gaps of ecological and applied importance for carbon sequestration.
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Affiliation(s)
- Hélène Iven
- Department of Environmental Systems Science, Institute of Agricultural Sciences, ETH Zurich, 8006, Zurich, Switzerland.
| | - Tom W N Walker
- Institute of Biology, University of Neuchâtel, 2000, Neuchâtel, Switzerland
- Department of Environmental Systems Science, Institute of Integrative Biology, ETH Zürich, 8006, Zurich, Switzerland
| | - Mark Anthony
- Department of Environmental Systems Science, Institute of Integrative Biology, ETH Zürich, 8006, Zurich, Switzerland
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24
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Impact of Microbial Uptake on the Nutrient Plume around Marine Organic Particles: High-Resolution Numerical Analysis. Microorganisms 2022; 10:microorganisms10102020. [PMID: 36296296 PMCID: PMC9611091 DOI: 10.3390/microorganisms10102020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 09/21/2022] [Accepted: 09/21/2022] [Indexed: 11/17/2022] Open
Abstract
The interactions between marine bacteria and particulate matter play a pivotal role in the biogeochemical cycles of carbon and associated inorganic elements in the oceans. Eutrophic plumes typically form around nutrient-releasing particles and host intense bacterial activities. However, the potential of bacteria to reshape the nutrient plumes remains largely unexplored. We present a high-resolution numerical analysis for the impacts of nutrient uptake by free-living bacteria on the pattern of dissolution around slow-moving particles. At the single-particle level, the nutrient field is parameterized by the Péclet and Damköhler numbers (0 < Pe < 1000, 0 < Da < 10) that quantify the relative contribution of advection, diffusion and uptake to nutrient transport. In spite of reducing the extent of the nutrient plume in the wake of the particle, bacterial uptake enhances the rates of particle dissolution and nutrient depletion. These effects are amplified when the uptake timescale is shorter than the plume lifetime (Pe/Da < 100, Da > 0.0001), while otherwise they are suppressed by advection or diffusion. Our analysis suggests that the quenching of eutrophic plumes is significant for individual phytoplankton cells, as well as marine aggregates with sizes ranging from 0.1 mm to 10 mm and sinking velocities up to 40 m per day. This microscale process has a large potential impact on microbial growth dynamics and nutrient cycling in marine ecosystems.
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25
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Arandia-Gorostidi N, Berthelot H, Calabrese F, Stryhanyuk H, Klawonn I, Iversen M, Nahar N, Grossart HP, Ploug H, Musat N. Efficient carbon and nitrogen transfer from marine diatom aggregates to colonizing bacterial groups. Sci Rep 2022; 12:14949. [PMID: 36056039 PMCID: PMC9440002 DOI: 10.1038/s41598-022-18915-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 08/22/2022] [Indexed: 11/24/2022] Open
Abstract
Bacterial degradation of sinking diatom aggregates is key for the availability of organic matter in the deep-ocean. Yet, little is known about the impact of aggregate colonization by different bacterial taxa on organic carbon and nutrient cycling within aggregates. Here, we tracked the carbon (C) and nitrogen (N) transfer from the diatom Leptocylindrus danicus to different environmental bacterial groups using a combination of 13C and 15N isotope incubation (incubated for 72 h), CARD-FISH and nanoSIMS single-cell analysis. Pseudoalteromonas bacterial group was the first colonizing diatom-aggregates, succeeded by the Alteromonas group. Within aggregates, diatom-attached bacteria were considerably more enriched in 13C and 15N than non-attached bacteria. Isotopic mass balance budget indicates that both groups showed comparable levels of diatom C in their biomass, accounting for 19 ± 7% and 15 ± 11%, respectively. In contrast to C, bacteria of the Alteromonas groups showed significantly higher levels of N derived from diatoms (77 ± 28%) than Pseudoalteromonas (47 ± 17%), suggesting a competitive advantage for Alteromonas in the N-limiting environments of the deep-sea. Our results imply that bacterial succession within diatom aggregates may largely impact taxa-specific C and N uptake, which may have important consequences for the quantity and quality of organic matter exported to the deep ocean.
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Affiliation(s)
- Nestor Arandia-Gorostidi
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research (UFZ), Permoserstrasse 15, 04318, Leipzig, Germany.
- Department of Earth System Science, Stanford University, Green Earth Sciences Building, 367 Panama St., Room 129, Stanford, CA, 94305-4216, USA.
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden.
| | - Hugo Berthelot
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research (UFZ), Permoserstrasse 15, 04318, Leipzig, Germany
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 UBO/CNRS/IRD/IFREMER, Institut Universitaire Européen de la Mer (IUEM), Brest, France
- IFREMER, DYNECO, Pelagos Laboratory, Plouzané, France
| | - Federica Calabrese
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research (UFZ), Permoserstrasse 15, 04318, Leipzig, Germany
- Department of Organismic and Evolutionary BiologyBiological Laboratories, Harvard University, 16 Divinity Avenue, Cambridge, MA, USA
| | - Hryhoriy Stryhanyuk
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research (UFZ), Permoserstrasse 15, 04318, Leipzig, Germany
| | - Isabell Klawonn
- Department of Ecology, Environment and Plant Sciences, Stockholm University, 10691, Stockholm, Sweden
- Leibniz Institute for Baltic Sea Research (IOW), Rostock, Germany
| | - Morten Iversen
- Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research, Bremerhaven, Germany
- Marum and University of Bremen, Bremen, Germany
| | - Nurun Nahar
- Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
- Biological and Environmental Sciences, University of Gothenburg, Box 461, 40530, Gothenburg, Sweden
| | - Hans-Peter Grossart
- Institute for Biochemistry and Biology, Potsdam University, Potsdam, Germany
- Department Plankton and Microbial Ecology, Leibniz Institute for Freshwater Ecology and Inland Fisheries, Berlin/Stechlin, Germany
| | - Helle Ploug
- Department of Marine Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Niculina Musat
- Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research (UFZ), Permoserstrasse 15, 04318, Leipzig, Germany.
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26
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Patel N, Guillemette R, Lal R, Azam F. Bacterial surface interactions with organic colloidal particles: Nanoscale hotspots of organic matter in the ocean. PLoS One 2022; 17:e0272329. [PMID: 36006971 PMCID: PMC9409529 DOI: 10.1371/journal.pone.0272329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 07/19/2022] [Indexed: 11/19/2022] Open
Abstract
Colloidal particles constitute a substantial fraction of organic matter in the global ocean and an abundant component of the organic matter interacting with bacterial surfaces. Using E. coli ribosomes as model colloidal particles, we applied high-resolution atomic force microscopy to probe bacterial surface interactions with organic colloids to investigate particle attachment and relevant surface features. We observed the formation of ribosome films associating with marine bacteria isolates and natural seawater assemblages, and that bacteria readily utilized the added ribosomes as growth substrate. In exposure experiments ribosomes directly attached onto bacterial surfaces as 40–200 nm clusters and patches of individual particles. We found that certain bacterial cells expressed surface corrugations that range from 50–100 nm in size, and 20 nm deep. Furthermore, our AFM studies revealed surface pits in select bacteria that range between 50–300 nm in width, and 10–50 nm in depth. Our findings suggest novel adaptive strategies of pelagic marine bacteria for colloid capture and utilization as nutrients, as well as storage as nanoscale hotspots of DOM.
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Affiliation(s)
- Nirav Patel
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
| | - Ryan Guillemette
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
| | - Ratnesh Lal
- Department of Bioengineering, University of California San Diego, La Jolla, California, United States of America
| | - Farooq Azam
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America
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27
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Barnett SE, Youngblut ND, Buckley DH. Bacterial community dynamics explain carbon mineralization and assimilation in soils of different land-use history. Environ Microbiol 2022; 24:5230-5247. [PMID: 35920035 DOI: 10.1111/1462-2920.16146] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 07/16/2022] [Accepted: 07/20/2022] [Indexed: 11/30/2022]
Abstract
Soil dwelling microorganisms are key players in the terrestrial carbon cycle, driving both the degradation and stabilization of soil organic matter. Bacterial community structure and function vary with respect to land-use, yet the ecological drivers of this variation remain poorly described and difficult to predict. We conducted a multi-substrate DNA-stable isotope probing experiment across cropland, old-field, and forest habitats to link carbon mineralization dynamics with the dynamics of bacterial growth and carbon assimilation. We tracked the movement of 13 C derived from five distinct carbon sources as it was assimilated into bacterial DNA over time. We show that carbon mineralization, community composition, and carbon assimilation dynamics all differed with respect to land-use. We also show that microbial community dynamics affect carbon assimilation dynamics and are associated with soil DNA content. Soil DNA yield is easy to measure and may be useful in predicting microbial community dynamics linked to soil carbon cycling. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Samuel E Barnett
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
| | - Nicholas D Youngblut
- Department of Microbiome Science, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Daniel H Buckley
- School of Integrative Plant Science, Cornell University, Ithaca, NY, USA
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28
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Historical contingencies and phage induction diversify bacterioplankton communities at the microscale. Proc Natl Acad Sci U S A 2022; 119:e2117748119. [PMID: 35862452 PMCID: PMC9335236 DOI: 10.1073/pnas.2117748119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In many natural environments, microorganisms decompose microscale resource patches made of complex organic matter. The growth and collapse of populations on these resource patches unfold within spatial ranges of a few hundred micrometers or less, making such microscale ecosystems hotspots of heterotrophic metabolism. Despite the potential importance of patch-level dynamics for the large-scale functioning of heterotrophic microbial communities, we have not yet been able to delineate the ecological processes that control natural populations at the microscale. Here, we address this challenge by characterizing the natural marine communities that assembled on over 1,000 individual microscale particles of chitin, the most abundant marine polysaccharide. Using low-template shotgun metagenomics and imaging, we find significant variation in microscale community composition despite the similarity in initial species pools across replicates. Chitin-degrading taxa that were rare in seawater established large populations on a subset of particles, resulting in a wide range of predicted chitinolytic abilities and biomass at the level of individual particles. We show, through a mathematical model, that this variability can be attributed to stochastic colonization and historical contingencies affecting the tempo of growth on particles. We find evidence that one biological process leading to such noisy growth across particles is differential predation by temperate bacteriophages of chitin-degrading strains, the keystone members of the community. Thus, initial stochasticity in assembly states on individual particles, amplified through ecological interactions, may have significant consequences for the diversity and functionality of systems of microscale patches.
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29
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Schwartzman JA, Ebrahimi A, Chadwick G, Sato Y, Roller BRK, Orphan VJ, Cordero OX. Bacterial growth in multicellular aggregates leads to the emergence of complex life cycles. Curr Biol 2022; 32:3059-3069.e7. [PMID: 35777363 PMCID: PMC9496226 DOI: 10.1016/j.cub.2022.06.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/03/2022] [Accepted: 06/07/2022] [Indexed: 01/12/2023]
Abstract
Facultative multicellular behaviors expand the metabolic capacity and physiological resilience of bacteria. Despite their ubiquity in nature, we lack an understanding of how these behaviors emerge from cellular-scale phenomena. Here, we show how the coupling between growth and resource gradient formation leads to the emergence of multicellular lifecycles in a marine bacterium. Under otherwise carbon-limited growth conditions, Vibrio splendidus 12B01 forms clonal multicellular groups to collectively harvest carbon from soluble polymers of the brown-algal polysaccharide alginate. As they grow, groups phenotypically differentiate into two spatially distinct sub-populations: a static "shell" surrounding a motile, carbon-storing "core." Differentiation of these two sub-populations coincides with the formation of a gradient in nitrogen-source availability within clusters. Additionally, we find that populations of cells containing a high proportion of carbon-storing individuals propagate and form new clusters more readily on alginate than do populations with few carbon-storing cells. Together, these results suggest that local metabolic activity and differential partitioning of resources leads to the emergence of reproductive cycles in a facultatively multicellular bacterium.
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Affiliation(s)
- Julia A Schwartzman
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - Ali Ebrahimi
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Grayson Chadwick
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Yuya Sato
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Benjamin R K Roller
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Center for Microbiology and Environmental Systems Science, University of Vienna, Djerassiplatz 1, Vienna 1030, Austria; Department of Environmental Systems Sciences, ETH Zürich, Universitätsstrasse 16, Zürich 8092, Switzerland; Department of Environmental Microbiology, Eawag, Ueberlandstrasse 133, Dübendorf 8600, Switzerland
| | - Victoria J Orphan
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Otto X Cordero
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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30
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Chen L, Zhao B, Palomo A, Sun Y, Cheng Z, Zhang M, Xia Y. Micron-scale biogeography reveals conservative intra anammox bacteria spatial co-associations. WATER RESEARCH 2022; 220:118640. [PMID: 35661503 DOI: 10.1016/j.watres.2022.118640] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 05/17/2022] [Accepted: 05/18/2022] [Indexed: 06/15/2023]
Abstract
Micron-scale resolution can help to reliably identify true taxon-taxon interactions in complex microbial communities. Despite widespread recognition of the critical role of metabolic interactions in anaerobic ammonium oxidation (anammox) system performance, no studies have examined microbial interactions at the micron-scale in anammox consortia. To fill this gap, we extensively sampled (totally 242 samples) the consortia of a lab-scale anammox reactor at different length scales, including bulk-scale (∼cm), macro-scale (300-500 µm) and micron-scale (70-100 µm). We firstly observed evident micron-scale heterogeneity in anammox consortia, with the relative abundance of anammox bacteria fluctuated greatly across individual clusters (2.0%-79.3%), indicating that the biotic interactions play a significant role in the assembly of anammox communities under well-controlled and well-mixed condition. Importantly, by mapping the spatial associations in anammox consortia at micron-scale, we demonstrated that the conserved co-associations for anammox bacteria were restricted to three different Brocadia species over time, and their co-associations with heterotrophs were random, implying that there was no statistically significant symbiotic interaction between anammox bacteria and other heterotrophic populations. Further metagenomic binning revealed that the quorum sensing with secondary messenger c-di-GMP potentially holding on the conservative metabolic cooperation among Brocadia species. These results shed new light on the social behavior of the anammox community. Overall, delineating of biological structures at micron-scale opens a new way of monitoring the microbial spatial structure and interactions, paving the way for improved community engineering of biotreatment systems.
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Affiliation(s)
- Liming Chen
- School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Bixi Zhao
- School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Alejandro Palomo
- School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yuhong Sun
- School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Zhanwen Cheng
- School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Miao Zhang
- School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen 518055, China
| | - Yu Xia
- School of Environmental Science and Engineering, College of Engineering, Southern University of Science and Technology, Shenzhen 518055, China; State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China; Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
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31
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Abstract
Biofilm formation is an important and ubiquitous mode of growth among bacteria. Central to the evolutionary advantage of biofilm formation is cell-cell and cell-surface adhesion achieved by a variety of factors, some of which are diffusible compounds that may operate as classical public goods-factors that are costly to produce but may benefit other cells. An outstanding question is how diffusible matrix production, in general, can be stable over evolutionary timescales. In this work, using Vibrio cholerae as a model, we show that shared diffusible biofilm matrix proteins are indeed susceptible to cheater exploitation and that the evolutionary stability of producing these matrix components fundamentally depends on biofilm spatial structure, intrinsic sharing mechanisms of these components, and flow conditions in the environment. We further show that exploitation of diffusible adhesion proteins is localized within a well-defined spatial range around cell clusters that produce them. Based on this exploitation range and the spatial distribution of cell clusters, we constructed a model of costly diffusible matrix production and related these length scales to the relatedness coefficient in social evolution theory. Our results show that production of diffusible biofilm matrix components is evolutionarily stable under conditions consistent with natural biofilm habitats and host environments. We expect the mechanisms revealed in this study to be relevant to other secreted factors that operate as cooperative public goods in bacterial communities and the concept of exploitation range and the associated analysis tools to be generally applicable.
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32
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Teschler JK, Nadell CD, Drescher K, Yildiz FH. Mechanisms Underlying Vibrio cholerae Biofilm Formation and Dispersion. Annu Rev Microbiol 2022; 76:503-532. [PMID: 35671532 DOI: 10.1146/annurev-micro-111021-053553] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Biofilms are a widely observed growth mode in which microbial communities are spatially structured and embedded in a polymeric extracellular matrix. Here, we focus on the model bacterium Vibrio cholerae and summarize the current understanding of biofilm formation, including initial attachment, matrix components, community dynamics, social interactions, molecular regulation, and dispersal. The regulatory network that orchestrates the decision to form and disperse from biofilms coordinates various environmental inputs. These cues are integrated by several transcription factors, regulatory RNAs, and second-messenger molecules, including bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP). Through complex mechanisms, V. cholerae weighs the energetic cost of forming biofilms against the benefits of protection and social interaction that biofilms provide. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Jennifer K Teschler
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, California, USA;
| | - Carey D Nadell
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | | | - Fitnat H Yildiz
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, California, USA;
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33
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Mridha S, Kümmerli R. Coordination of siderophore gene expression among clonal cells of the bacterium Pseudomonas aeruginosa. Commun Biol 2022; 5:545. [PMID: 35668142 PMCID: PMC9170778 DOI: 10.1038/s42003-022-03493-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 05/18/2022] [Indexed: 11/09/2022] Open
Abstract
AbstractThere has been great progress in understanding how bacterial groups coordinate social actions, such as biofilm formation and public-goods secretion. Less clear is whether the seemingly coordinated group-level responses actually mirror what individual cells do. Here, we use a microscopy approach to simultaneously quantify the investment of individual cells of the bacterium Pseudomonas aeruginosa into two public goods, the siderophores pyochelin and pyoverdine. Using gene expression as a proxy for investment, we initially observe no coordination but high heterogeneity and bimodality in siderophore investment across cells. With increasing cell density, gene expression becomes more homogenized across cells, accompanied by a moderate shift from pyochelin to pyoverdine expression. We find positive associations in the expression of pyochelin and pyoverdine genes across cells, with cell-to-cell variation correlating with cellular metabolic states. Our work suggests that siderophore-mediated signalling aligns behaviour of individuals over time and spurs a coordinated three-phase siderophore investment cycle.
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34
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Wang M, Chen X, Tang Y, Nie Y, Wu X. Substrate availability and toxicity shape the structure of microbial communities engaged in metabolic division of labor. MLIFE 2022; 1:131-145. [PMID: 38817679 PMCID: PMC10989799 DOI: 10.1002/mlf2.12025] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 05/05/2022] [Accepted: 05/08/2022] [Indexed: 06/01/2024]
Abstract
Metabolic division of labor (MDOL) represents a widespread natural phenomenon, whereby a complex metabolic pathway is shared between different strains within a community in a mutually beneficial manner. However, little is known about how the composition of such a microbial community is regulated. We hypothesized that when degradation of an organic compound is carried out via MDOL, the concentration and toxicity of the substrate modulate the benefit allocation between the two microbial populations, thus affecting the structure of this community. We tested this hypothesis by combining modeling with experiments using a synthetic consortium. Our modeling analysis suggests that the proportion of the population executing the first metabolic step can be simply estimated by Monod-like formulas governed by substrate concentration and toxicity. Our model and the proposed formula were able to quantitatively predict the structure of our synthetic consortium. Further analysis demonstrates that our rule is also applicable in estimating community structures in spatially structured environments. Together, our work clearly demonstrates that the structure of MDOL communities can be quantitatively predicted using available information on environmental factors, thus providing novel insights into how to manage artificial microbial systems for the wide application of the bioindustry.
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Affiliation(s)
- Miaoxiao Wang
- Department of Energy & Resources Engineering, College of EngineeringPeking UniversityBeijingChina
- Department of Environmental Systems ScienceETH ZürichZürichSwitzerland
- Department of Environmental MicrobiologyEawagDübendorfSwitzerland
- Department of Environmental Science and Engineering, College of Architecture and EnvironmentSichuan UniversityChengduChina
| | - Xiaoli Chen
- Department of Energy & Resources Engineering, College of EngineeringPeking UniversityBeijingChina
- Institute of Ocean ResearchPeking UniversityBeijingChina
| | - Yue‐Qin Tang
- Department of Environmental Science and Engineering, College of Architecture and EnvironmentSichuan UniversityChengduChina
| | - Yong Nie
- Department of Energy & Resources Engineering, College of EngineeringPeking UniversityBeijingChina
| | - Xiao‐Lei Wu
- Department of Energy & Resources Engineering, College of EngineeringPeking UniversityBeijingChina
- Institute of Ocean ResearchPeking UniversityBeijingChina
- Institute of EcologyPeking UniversityBeijingChina
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35
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Qu L, Cai R, Hu Z, Wang H. Metagenomic assemblage genomes analyses reveal the polysaccharides hydrolyzing potential of marine group II euryarchaea. ENVIRONMENTAL RESEARCH 2022; 209:112865. [PMID: 35120891 DOI: 10.1016/j.envres.2022.112865] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 01/02/2022] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Marine group II euryarchaea (MGII) dominates the planktonic archaeal community in global surface seawater and is associated to particulate organic matters mainly composed of polysaccharides. However, the polysaccharides metabolism of MGII euryarchaea is unclear. In this study, the distribution and polysaccharides metabolism potential of MGII euryarchaea in the estuary were investigated. High-throughput sequencing of 16S rRNA genes showed that MGII euryarchaea was the predominant archaeal group in the Pearl River Estuary (PRE), and the relative abundance of MGII euryarchaea in particle-attached fraction was higher than that in free-living fractions. A total of 19 metagenome-assembled genomes (MAGs) were successfully reconstructed from metagenomic data, of which 10 MAGs were grouped as MGII euryarchaea according to phylogenomic analysis. Genes encoding a variety of carbohydrate-active enzymes (CAZymes) were found in MAGs/genomes of MGII euryarchaea. These CAZymes annotated in MAGs were capable of hydrolyzing many polysaccharides, including α-glucans, β-glucans, xylans, nitrogen-containing polysaccharides, and some insoluble galactans. The results also indicated that MGII euryarchaea has some unique enzymes that can hydrolyze starch, β-1,3-glucans, complex xylans, carrageenan, and agarose. Collectively, our results demonstrated that MGII euryarchaea has great polysaccharides hydrolysis potential and could play an important role in the carbon cycle of marine ecosystem.
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Affiliation(s)
- Liping Qu
- Biology Department and Institute of Marine Sciences, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, 515063, China
| | - Runlin Cai
- Biology Department and Institute of Marine Sciences, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, 515063, China
| | - Zhong Hu
- Biology Department and Institute of Marine Sciences, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, 515063, China; Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, 511458, China
| | - Hui Wang
- Biology Department and Institute of Marine Sciences, College of Science, Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, 515063, China; Southern Marine Science and Engineering Guangdong Laboratory, Guangzhou, 511458, China.
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36
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Nguyen TTH, Zakem EJ, Ebrahimi A, Schwartzman J, Caglar T, Amarnath K, Alcolombri U, Peaudecerf FJ, Hwa T, Stocker R, Cordero OX, Levine NM. Microbes contribute to setting the ocean carbon flux by altering the fate of sinking particulates. Nat Commun 2022; 13:1657. [PMID: 35351873 PMCID: PMC8964765 DOI: 10.1038/s41467-022-29297-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 03/02/2022] [Indexed: 11/25/2022] Open
Abstract
Sinking particulate organic carbon out of the surface ocean sequesters carbon on decadal to millennial timescales. Predicting the particulate carbon flux is therefore critical for understanding both global carbon cycling and the future climate. Microbes play a crucial role in particulate organic carbon degradation, but the impact of depth-dependent microbial dynamics on ocean-scale particulate carbon fluxes is poorly understood. Here we scale-up essential features of particle-associated microbial dynamics to understand the large-scale vertical carbon flux in the ocean. Our model provides mechanistic insight into the microbial contribution to the particulate organic carbon flux profile. We show that the enhanced transfer of carbon to depth can result from populations struggling to establish colonies on sinking particles due to diffusive nutrient loss, cell detachment, and mortality. These dynamics are controlled by the interaction between multiple biotic and abiotic factors. Accurately capturing particle-microbe interactions is essential for predicting variability in large-scale carbon cycling. Micro-scale microbial community dynamics can substantially alter the fate of sinking particulates in the ocean thus playing a key role in setting the vertical flux of particulate carbon in the ocean.
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37
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Ebrahimi A, Goyal A, Cordero OX. Particle foraging strategies promote microbial diversity in marine environments. eLife 2022; 11:73948. [PMID: 35289269 PMCID: PMC8956285 DOI: 10.7554/elife.73948] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 03/01/2022] [Indexed: 11/26/2022] Open
Abstract
Microbial foraging in patchy environments, where resources are fragmented into particles or pockets embedded in a large matrix, plays a key role in natural environments. In the oceans and freshwater systems, particle-associated bacteria can interact with particle surfaces in different ways: some colonize only during short transients, while others form long-lived, stable colonies. We do not yet understand the ecological mechanisms by which both short- and long-term colonizers can coexist. Here, we address this problem with a mathematical model that explains how marine populations with different detachment rates from particles can stably coexist. In our model, populations grow only while on particles, but also face the increased risk of mortality by predation and sinking. Key to coexistence is the idea that detachment from particles modulates both net growth and mortality, but in opposite directions, creating a trade-off between them. While slow-detaching populations show the highest growth return (i.e., produce more net offspring), they are more susceptible to suffer higher rates of mortality than fast-detaching populations. Surprisingly, fluctuating environments, manifesting as blooms of particles (favoring growth) and predators (favoring mortality) significantly expand the likelihood that populations with different detachment rates can coexist. Our study shows how the spatial ecology of microbes in the ocean can lead to a predictable diversification of foraging strategies and the coexistence of multiple taxa on a single growth-limiting resource.
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Affiliation(s)
- Ali Ebrahimi
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, United States
| | - Akshit Goyal
- Department of Physics, Massachusetts Institute of Technology, Cambridge, United States
| | - Otto X Cordero
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, United States
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38
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Gopalakrishnappa C, Gowda K, Prabhakara KH, Kuehn S. An ensemble approach to the structure-function problem in microbial communities. iScience 2022; 25:103761. [PMID: 35141504 PMCID: PMC8810406 DOI: 10.1016/j.isci.2022.103761] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The metabolic activity of microbial communities plays a primary role in the flow of essential nutrients throughout the biosphere. Molecular genetics has revealed the metabolic pathways that model organisms utilize to generate energy and biomass, but we understand little about how the metabolism of diverse, natural communities emerges from the collective action of its constituents. We propose that quantifying and mapping metabolic fluxes to sequencing measurements of genomic, taxonomic, or transcriptional variation across an ensemble of diverse communities, either in the laboratory or in the wild, can reveal low-dimensional descriptions of community structure that can explain or predict their emergent metabolic activity. We survey the types of communities for which this approach might be best suited, review the analytical techniques available for quantifying metabolite fluxes in communities, and discuss what types of data analysis approaches might be lucrative for learning the structure-function mapping in communities from these data.
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Affiliation(s)
| | - Karna Gowda
- Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA
- Center for the Physics of Evolving Systems, University of Chicago, Chicago, IL 60637, USA
| | - Kaumudi H. Prabhakara
- Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA
- Center for the Physics of Evolving Systems, University of Chicago, Chicago, IL 60637, USA
| | - Seppe Kuehn
- Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA
- Center for the Physics of Evolving Systems, University of Chicago, Chicago, IL 60637, USA
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39
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Sichert A, Cordero OX. Polysaccharide-Bacteria Interactions From the Lens of Evolutionary Ecology. Front Microbiol 2021; 12:705082. [PMID: 34690949 PMCID: PMC8531407 DOI: 10.3389/fmicb.2021.705082] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 09/09/2021] [Indexed: 11/29/2022] Open
Abstract
Microbes have the unique ability to break down the complex polysaccharides that make up the bulk of organic matter, initiating a cascade of events that leads to their recycling. Traditionally, the rate of organic matter degradation is perceived to be limited by the chemical and physical structure of polymers. Recent advances in microbial ecology, however, suggest that polysaccharide persistence can result from non-linear growth dynamics created by the coexistence of alternate degradation strategies, metabolic roles as well as by ecological interactions between microbes. This complex "landscape" of degradation strategies and interspecific interactions present in natural microbial communities appears to be far from evolutionarily stable, as frequent gene gain and loss reshape enzymatic repertoires and metabolic roles. In this perspective, we discuss six challenges at the heart of this problem, ranging from the evolution of genetic repertoires, phenotypic heterogeneity in clonal populations, the development of a trait-based ecology, and the impact of metabolic interactions and microbial cooperation on degradation rates. We aim to reframe some of the key questions in the study of polysaccharide-bacteria interactions in the context of eco-evolutionary dynamics, highlighting possible research directions that, if pursued, would advance our understanding of polysaccharide degraders at the interface between biochemistry, ecology and evolution.
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40
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Pringault O, Bouvy M, Carre C, Mejri K, Bancon-Montigny C, Gonzalez C, Leboulanger C, Hlaili AS, Goni-Urriza M. Chemical contamination alters the interactions between bacteria and phytoplankton. CHEMOSPHERE 2021; 278:130457. [PMID: 34126687 DOI: 10.1016/j.chemosphere.2021.130457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 03/24/2021] [Accepted: 03/28/2021] [Indexed: 06/12/2023]
Abstract
Bacteria and phytoplankton are key players in aquatic ecosystem functioning. Their interactions mediate carbon transfer through the trophic web. Chemical contamination can alter the function and diversity of phytoplankton and bacterioplankton, with important consequences for ecosystem functioning. The aim of the present study was to assess the impact of chemical contamination on the interactions between both biological compartments. Two contrasting marine coastal ecosystems, offshore waters and lagoon waters, were exposed to chemical contamination (artificial or produced from resuspension of contaminated sediment) in microcosms in four seasons characterized by distinct phytoplankton communities. Offshore waters were characterized by a complex phytoplankton-bacterioplankton network with a predominance of positive interactions between both compartments, especially with Haptophyta, Cryptophyta, and dinoflagellates. In contrast, for lagoon waters, the phytoplankton-bacterioplankton network was simpler with a prevalence of negative interactions with Ochrophyta, Cryptophyta, and flagellates. Contamination with an artificial mix of pesticides and trace metal elements resulted in a decrease in the number of interactions between phytoplankton and bacterioplankton, especially for offshore waters. Resuspension of contaminated sediment also altered the interactions between both compartments. The release of nutrients stored in the sediment allowed the growth of nutrient limited phytoplankton species with marked consequences for the interactions with bacterioplankton, with a predominance of positive interactions, whereas in lagoon waters, negative interactions were mostly observed. Overall, this study showed that chemical contamination and sediment resuspension resulted in significant effects on phytoplankton-bacterioplankton interactions that can alter the functioning of anthropogenic coastal ecosystems.
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Affiliation(s)
- Olivier Pringault
- Aix Marseille Université, Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France; MARBEC Univ Montpellier, IRD, Ifremer, Montpellier, France; Faculté des Sciences de Bizerte, Université de Carthage, 7021, Zarzouna, Bizerte, France.
| | - Marc Bouvy
- MARBEC Univ Montpellier, IRD, Ifremer, Montpellier, France
| | - Claire Carre
- MARBEC Univ Montpellier, IRD, Ifremer, Montpellier, France
| | - Kaouther Mejri
- Faculté des Sciences de Bizerte, Université de Carthage, 7021, Zarzouna, Bizerte, France
| | | | | | | | - Asma Sakka Hlaili
- Faculté des Sciences de Bizerte, Université de Carthage, 7021, Zarzouna, Bizerte, France; Laboratoire d'Ecologie, de Biologie et de Physiologie des Organismes Aquatiques, LR18ES41, Université de Tunis El Manar, Tunis, France
| | - Marisol Goni-Urriza
- Universite de Pau et des Pays de L'Adour, E2S UPPA, CNRS, IPREM, 64000, Pau, France
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41
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Figueiredo ART, Wagner A, Kümmerli R. Ecology drives the evolution of diverse social strategies in Pseudomonas aeruginosa. Mol Ecol 2021; 30:5214-5228. [PMID: 34390514 PMCID: PMC9291133 DOI: 10.1111/mec.16119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 06/03/2021] [Accepted: 07/28/2021] [Indexed: 11/27/2022]
Abstract
Bacteria often cooperate by secreting molecules that can be shared as public goods between cells. Because the production of public goods is subject to cheating by mutants that exploit the good without contributing to it, there has been great interest in elucidating the evolutionary forces that maintain cooperation. However, little is known about how bacterial cooperation evolves under conditions where cheating is unlikely to be of importance. Here we use experimental evolution to follow changes in the production of a model public good, the iron‐scavenging siderophore pyoverdine, of the bacterium Pseudomonas aeruginosa. After 1200 generations of evolution in nine different environments, we observed that cheaters only reached high frequency in liquid medium with low iron availability. Conversely, when adding iron to reduce the cost of producing pyoverdine, we observed selection for pyoverdine hyperproducers. Similarly, hyperproducers also spread in populations evolved in highly viscous media, where relatedness between interacting individuals is increased. Whole‐genome sequencing of evolved clones revealed that hyperproduction is associated with mutations involving genes encoding quorum‐sensing communication systems, while cheater clones had mutations in the iron‐starvation sigma factor or in pyoverdine biosynthesis genes. Our findings demonstrate that bacterial social traits can evolve rapidly in divergent directions, with particularly strong selection for increased levels of cooperation occurring in environments where individual dispersal is reduced, as predicted by social evolution theory. Moreover, we establish a regulatory link between pyoverdine production and quorum‐sensing, showing that increased cooperation with respect to one trait (pyoverdine) can be associated with the loss (quorum‐sensing) of another social trait.
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Affiliation(s)
- Alexandre R T Figueiredo
- Department of Quantitative Biomedicine, University of Zurich, 8057, Zurich, Switzerland.,Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057, Zurich, Switzerland.,Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
| | - Andreas Wagner
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057, Zurich, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland.,The Santa Fe Institute, Santa Fe, New Mexico, United States of America
| | - Rolf Kümmerli
- Department of Quantitative Biomedicine, University of Zurich, 8057, Zurich, Switzerland.,Department of Plant and Microbial Biology, University of Zurich, 8008, Zurich, Switzerland
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42
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Gralka M, Szabo R, Stocker R, Cordero OX. Trophic Interactions and the Drivers of Microbial Community Assembly. Curr Biol 2021; 30:R1176-R1188. [PMID: 33022263 DOI: 10.1016/j.cub.2020.08.007] [Citation(s) in RCA: 107] [Impact Index Per Article: 35.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Despite numerous surveys of gene and species content in heterotrophic microbial communities, such as those found in animal guts, oceans, or soils, it is still unclear whether there are generalizable biological or ecological processes that control their dynamics and function. Here, we review experimental and theoretical advances to argue that networks of trophic interactions, in which the metabolic excretions of one species are the primary resource for another, constitute the central drivers of microbial community assembly. Trophic interactions emerge from the deconstruction of complex forms of organic matter into a wealth of smaller metabolic intermediates, some of which are released to the environment and serve as a nutritional buffet for the community. The structure of the emergent trophic network and the rate at which primary resources are supplied control many features of microbial community assembly, including the relative contributions of competition and cooperation and the emergence of alternative community states. Viewing microbial community assembly through the lens of trophic interactions also has important implications for the spatial dynamics of communities as well as the functional redundancy of taxonomic groups. Given the ubiquity of trophic interactions across environments, they impart a common logic that can enable the development of a more quantitative and predictive microbial community ecology.
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Affiliation(s)
- Matti Gralka
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Rachel Szabo
- Microbiology Graduate Program, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Roman Stocker
- Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich 8093, Switzerland
| | - Otto X Cordero
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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43
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Pollak S, Gralka M, Sato Y, Schwartzman J, Lu L, Cordero OX. Public good exploitation in natural bacterioplankton communities. SCIENCE ADVANCES 2021; 7:7/31/eabi4717. [PMID: 34321201 PMCID: PMC8318375 DOI: 10.1126/sciadv.abi4717] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 06/10/2021] [Indexed: 05/19/2023]
Abstract
Bacteria often interact with their environment through extracellular molecules that increase access to limiting resources. These secretions can act as public goods, creating incentives for exploiters to invade and "steal" public goods away from producers. This phenomenon has been studied extensively in vitro, but little is known about the occurrence and impact of public good exploiters in the environment. Here, we develop a genomic approach to systematically identify bacteria that can exploit public goods produced during the degradation of polysaccharides. Focusing on chitin, a highly abundant marine biopolymer, we show that public good exploiters are active in natural chitin degrading microbial communities, invading early during colonization, and potentially hindering degradation. In contrast to in vitro studies, we find that exploiters and degraders belong to distant lineages, facilitating their coexistence. Our approach opens novel avenues to use the wealth of genomic data available to infer ecological roles and interactions among microbes.
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Affiliation(s)
- Shaul Pollak
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Matti Gralka
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yuya Sato
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Environmental Management Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan
| | - Julia Schwartzman
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Lu Lu
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Otto X Cordero
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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44
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Both Pseudomonas aeruginosa and Candida albicans Accumulate Greater Biomass in Dual-Species Biofilms under Flow. mSphere 2021; 6:e0041621. [PMID: 34160236 PMCID: PMC8265656 DOI: 10.1128/msphere.00416-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Microbe-microbe interactions can strongly influence growth and biofilm formation kinetics. For Pseudomonas aeruginosa and Candida albicans, which are found together in diverse clinical sites, including urinary and intravenous catheters and the lungs of individuals with cystic fibrosis (CF), we compared the kinetics of biofilm formation by each species in dual-species and single-species biofilms. We engineered fluorescent protein constructs for P. aeruginosa (producing mKO-κ) and C. albicans (producing mKate2) that did not alter growth and enabled single-cell resolution imaging by live-sample microscopy. Using these strains in an optically clear derivative of synthetic CF sputum medium, we found that both P. aeruginosa and C. albicans displayed increased biovolume accumulation—by three- and sixfold, respectively—in dual-species biofilms relative to single-species biofilms. This result was specific to the biofilm environment, as enhanced growth was not observed in planktonic cocultures. Stimulation of C. albicans biofilm formation occurred regardless of whether P. aeruginosa was added at the time of fungal inoculation or 24 h after the initiation of biofilm development. P. aeruginosa biofilm increases in cocultures did not require the Pel extracellular polysaccharide, phenazines, and siderophores known to influence C. albicans. P. aeruginosa mutants lacking Anr, LasR, and BapA were not significantly stimulated by C. albicans, but they still promoted a significant enhancement of biofilm development of the fungus, suggesting a fungal response to the presence of bacteria. Last, we showed that a set of P. aeruginosa clinical isolates also prompted an increase of biovolume by C. albicans in coculture. IMPORTANCE There is an abundance of work on both P. aeruginosa and C. albicans in isolation, and quite some work as well on the way these two microbes interact. These studies do not, however, consider biofilm environments under flow, and our results here show that the expected outcome of interaction between these two pathogens can actually be reversed under flow, from pure antagonism to an increase in biomass on the part of both. Our work also highlights the importance of cellular-scale spatial structure in biofilms for understanding multispecies population dynamics.
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45
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Wucher BR, Elsayed M, Adelman JS, Kadouri DE, Nadell CD. Bacterial predation transforms the landscape and community assembly of biofilms. Curr Biol 2021; 31:2643-2651.e3. [PMID: 33826904 PMCID: PMC8588571 DOI: 10.1016/j.cub.2021.03.036] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 02/02/2021] [Accepted: 03/10/2021] [Indexed: 01/10/2023]
Abstract
The bacterium Bdellovibrio bacteriovorus attaches to the exterior of a Gram-negative prey cell, enters the periplasm, and harvests resources to replicate before lysing the host to find new prey.1-7 Predatory bacteria such as this are common in many natural environments,8-13 as are groups of matrix-bound prey cell clusters, termed biofilms.14-16 Despite the ubiquity of both predatory bacteria and biofilm-dwelling prey, the interaction between B. bacteriovorus and prey inside biofilms has received little attention and has not yet been studied at the micrometer scale. Filling this knowledge gap is critical to understanding bacterial predator-prey interaction in nature. Here we show that B. bacteriovorus is able to attack biofilms of the pathogen Vibrio cholerae, but only up until a critical maturation threshold past which the prey biofilms are protected from their predators. Using high-resolution microscopy and detailed spatial analysis, we determine the relative contributions of matrix secretion and cell-cell packing of the prey biofilm toward this protection mechanism. Our results demonstrate that B. bacteriovorus predation in the context of this protection threshold fundamentally transforms the sub-millimeter-scale landscape of biofilm growth, as well as the process of community assembly as new potential biofilm residents enter the system. We conclude that bacterial predation can be a key factor influencing the spatial community ecology of microbial biofilms.
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Affiliation(s)
- Benjamin R Wucher
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA
| | - Mennat Elsayed
- Department of Oral Biology, Rutgers School of Dental Medicine, 110 Bergen Street, Newark, NJ 07101, USA
| | - James S Adelman
- Department of Biological Sciences, The University of Memphis, 3700 Walker Avenue, Memphis, TN 38117, USA
| | - Daniel E Kadouri
- Department of Oral Biology, Rutgers School of Dental Medicine, 110 Bergen Street, Newark, NJ 07101, USA
| | - Carey D Nadell
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH 03755, USA.
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46
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Bunse C, Koch H, Breider S, Simon M, Wietz M. Sweet spheres: succession and CAZyme expression of marine bacterial communities colonizing a mix of alginate and pectin particles. Environ Microbiol 2021; 23:3130-3148. [PMID: 33876546 DOI: 10.1111/1462-2920.15536] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/06/2021] [Accepted: 04/15/2021] [Indexed: 12/24/2022]
Abstract
Polysaccharide particles are important substrates and microhabitats for marine bacteria. However, substrate-specific bacterial dynamics in mixtures of particle types with different polysaccharide composition, as likely occurring in natural habitats, are undescribed. Here, we studied the composition, functional diversity and gene expression of marine bacterial communities colonizing a mix of alginate and pectin particles. Amplicon, metagenome and metatranscriptome sequencing revealed that communities on alginate and pectin particles significantly differed from their free-living counterparts. Unexpectedly, microbial dynamics on alginate and pectin particles were similar, with predominance of amplicon sequence variants (ASVs) from Tenacibaculum, Colwellia, Psychrobium and Psychromonas. Corresponding metagenome-assembled genomes (MAGs) expressed diverse alginate lyases, several colocalized in polysaccharide utilization loci. Only a single, low-abundant MAG showed elevated transcript abundances of pectin-degrading enzymes. One specific Glaciecola ASV dominated the free-living fraction, possibly persisting on particle-derived oligomers through different glycoside hydrolases. Elevated ammonium uptake and metabolism signified nitrogen as an important factor for degrading carbon-rich particles, whereas elevated methylcitrate and glyoxylate cycles suggested nutrient limitation in surrounding waters. The bacterial preference for alginate, whereas pectin primarily served as colonization scaffold, illuminates substrate-driven dynamics within mixed polysaccharide pools. These insights expand our understanding of bacterial niche specialization and the biological carbon pump in macroalgae-rich habitats.
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Affiliation(s)
- Carina Bunse
- Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg, Oldenburg, Germany.,Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Hanna Koch
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany.,Department of Microbiology, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Sven Breider
- Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Meinhard Simon
- Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg, Oldenburg, Germany.,Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
| | - Matthias Wietz
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany.,Institute for Chemistry and Biology of the Marine Environment, University of Oldenburg, Oldenburg, Germany
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47
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Pacheco AR, Osborne ML, Segrè D. Non-additive microbial community responses to environmental complexity. Nat Commun 2021; 12:2365. [PMID: 33888697 PMCID: PMC8062479 DOI: 10.1038/s41467-021-22426-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 03/15/2021] [Indexed: 02/07/2023] Open
Abstract
Environmental composition is a major, though poorly understood, determinant of microbiome dynamics. Here we ask whether general principles govern how microbial community growth yield and diversity scale with an increasing number of environmental molecules. By assembling hundreds of synthetic consortia in vitro, we find that growth yield can remain constant or increase in a non-additive manner with environmental complexity. Conversely, taxonomic diversity is often much lower than expected. To better understand these deviations, we formulate metrics for epistatic interactions between environments and use them to compare our results to communities simulated with experimentally-parametrized consumer resource models. We find that key metabolic and ecological factors, including species similarity, degree of specialization, and metabolic interactions, modulate the observed non-additivity and govern the response of communities to combinations of resource pools. Our results demonstrate that environmental complexity alone is not sufficient for maintaining community diversity, and provide practical guidance for designing and controlling microbial ecosystems.
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Affiliation(s)
- Alan R Pacheco
- Graduate Program in Bioinformatics, Boston University, Boston, MA, USA
- Biological Design Center, Boston University, Boston, MA, USA
| | - Melisa L Osborne
- Graduate Program in Bioinformatics, Boston University, Boston, MA, USA
- Biological Design Center, Boston University, Boston, MA, USA
| | - Daniel Segrè
- Graduate Program in Bioinformatics, Boston University, Boston, MA, USA.
- Biological Design Center, Boston University, Boston, MA, USA.
- Department of Biology, Boston University, Boston, MA, USA.
- Department of Biomedical Engineering, Boston University, Boston, MA, USA.
- Department of Physics, Boston University, Boston, MA, USA.
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Liu F, Giometto A, Wu M. Microfluidic and mathematical modeling of aquatic microbial communities. Anal Bioanal Chem 2021; 413:2331-2344. [PMID: 33244684 PMCID: PMC7990691 DOI: 10.1007/s00216-020-03085-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 11/05/2020] [Accepted: 11/19/2020] [Indexed: 01/27/2023]
Abstract
Aquatic microbial communities contribute fundamentally to biogeochemical transformations in natural ecosystems, and disruption of these communities can lead to ecological disasters such as harmful algal blooms. Microbial communities are highly dynamic, and their composition and function are tightly controlled by the biophysical (e.g., light, fluid flow, and temperature) and biochemical (e.g., chemical gradients and cell concentration) parameters of the surrounding environment. Due to the large number of environmental factors involved, a systematic understanding of the microbial community-environment interactions is lacking. In this article, we show that microfluidic platforms present a unique opportunity to recreate well-defined environmental factors in a laboratory setting in a high throughput way, enabling quantitative studies of microbial communities that are amenable to theoretical modeling. The focus of this article is on aquatic microbial communities, but the microfluidic and mathematical models discussed here can be readily applied to investigate other microbiomes.
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Affiliation(s)
- Fangchen Liu
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Andrea Giometto
- School of Civil and Environmental Engineering, Cornell University, Ithaca, NY, 14853, USA
| | - Mingming Wu
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, 14853, USA.
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Nutrient complexity triggers transitions between solitary and colonial growth in bacterial populations. ISME JOURNAL 2021; 15:2614-2626. [PMID: 33731836 PMCID: PMC8397785 DOI: 10.1038/s41396-021-00953-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 02/18/2021] [Accepted: 02/25/2021] [Indexed: 12/31/2022]
Abstract
Microbial populations often experience fluctuations in nutrient complexity in their natural environment such as between high molecular weight polysaccharides and simple monosaccharides. However, it is unclear if cells can adopt growth behaviors that allow individuals to optimally respond to differences in nutrient complexity. Here, we directly control nutrient complexity and use quantitative single-cell analysis to study the growth dynamics of individuals within populations of the aquatic bacterium Caulobacter crescentus. We show that cells form clonal microcolonies when growing on the polysaccharide xylan, which is abundant in nature and degraded using extracellular cell-linked enzymes; and disperse to solitary growth modes when the corresponding monosaccharide xylose becomes available or nutrients are exhausted. We find that the cellular density required to achieve maximal growth rates is four-fold higher on xylan than on xylose, indicating that aggregating is advantageous on polysaccharides. When collectives on xylan are transitioned to xylose, cells start dispersing, indicating that colony formation is no longer beneficial and solitary behaviors might serve to reduce intercellular competition. Our study demonstrates that cells can dynamically tune their behaviors when nutrient complexity fluctuates, elucidates the quantitative advantages of distinct growth behaviors for individual cells and indicates why collective growth modes are prevalent in microbial populations.
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Competitive Exclusion and Metabolic Dependency among Microorganisms Structure the Cellulose Economy of an Agricultural Soil. mBio 2021; 12:mBio.03099-20. [PMID: 33402535 PMCID: PMC8545098 DOI: 10.1128/mbio.03099-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microorganisms that degrade cellulose utilize extracellular reactions that yield free by-products which can promote interactions with noncellulolytic organisms. We hypothesized that these interactions determine the ecological and physiological traits governing the fate of cellulosic carbon (C) in soil. We performed comparative genomics with genome bins from a shotgun metagenomic-stable isotope probing experiment to characterize the attributes of cellulolytic and noncellulolytic taxa accessing 13C from cellulose. We hypothesized that cellulolytic taxa would exhibit competitive traits that limit access, while noncellulolytic taxa would display greater metabolic dependency, such as signatures of adaptive gene loss. We tested our hypotheses by evaluating genomic traits indicative of competitive exclusion or metabolic dependency, such as antibiotic production, growth rate, surface attachment, biomass degrading potential, and auxotrophy. The most 13C-enriched taxa were cellulolytic Cellvibrio (Gammaproteobacteria) and Chaetomium (Ascomycota), which exhibited a strategy of self-sufficiency (prototrophy), rapid growth, and competitive exclusion via antibiotic production. Auxotrophy was more prevalent in cellulolytic Actinobacteria than in cellulolytic Proteobacteria, demonstrating differences in dependency among cellulose degraders. Noncellulolytic taxa that accessed 13C from cellulose (Planctomycetales, Verrucomicrobia, and Vampirovibrionales) were also more dependent, as indicated by patterns of auxotrophy and 13C labeling (i.e., partial labeling or labeling at later stages). Major 13C-labeled cellulolytic microbes (e.g., Sorangium, Actinomycetales, Rhizobiales, and Caulobacteraceae) possessed adaptations for surface colonization (e.g., gliding motility, hyphae, attachment structures) signifying the importance of surface ecology in decomposing particulate organic matter. Our results demonstrated that access to cellulosic C was accompanied by ecological trade-offs characterized by differing degrees of metabolic dependency and competitive exclusion.
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