1
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Dupuis S, Lingappa UF, Mayali X, Sindermann ES, Chastain JL, Weber PK, Stuart R, Merchant SS. Scarcity of fixed carbon transfer in a model microbial phototroph-heterotroph interaction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.26.577492. [PMID: 38328118 PMCID: PMC10849638 DOI: 10.1101/2024.01.26.577492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Although the green alga Chlamydomonas reinhardtii has long served as a reference organism, few studies have interrogated its role as a primary producer in microbial interactions. Here, we quantitatively investigated C. reinhardtii's capacity to support a heterotrophic microbe using the established coculture system with Mesorhizobium japonicum , a vitamin B 12 -producing α-proteobacterium. Using stable isotope probing and nanoscale secondary ion mass spectrometry (nanoSIMS), we tracked the flow of photosynthetic fixed carbon and consequent bacterial biomass synthesis under continuous and diurnal light with single-cell resolution. We found that more 13 C fixed by the alga was taken up by bacterial cells under continuous light, invalidating the hypothesis that the alga's fermentative degradation of starch reserves during the night would boost M. japonicum heterotrophy. 15 NH 4 assimilation rates and changes in cell size revealed that M. japonicum cells reduced new biomass synthesis in coculture with the alga but continued to divide - a hallmark of nutrient limitation often referred to as reductive division. Despite this sign of starvation, the bacterium still synthesized vitamin B 12 and supported the growth of a B 12 -dependent C. reinhardtii mutant. Finally, we showed that bacterial proliferation could be supported solely by the algal lysis that occurred in coculture, highlighting the role of necromass in carbon cycling. Collectively, these results reveal the scarcity of fixed carbon in this microbial trophic relationship (particularly under environmentally relevant light regimes), demonstrate B 12 exchange even during bacterial starvation, and underscore the importance of quantitative approaches for assessing metabolic coupling in algal-bacterial interactions.
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2
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Hallberg ZF, Nicolas AM, Alvarez-Aponte ZI, Mok KC, Sieradzki ET, Pett-Ridge J, Banfield JF, Carlson HK, Firestone MK, Taga ME. Soil microbial community response to corrinoids is shaped by a natural reservoir of vitamin B 12. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.12.580003. [PMID: 38405713 PMCID: PMC10888822 DOI: 10.1101/2024.02.12.580003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Soil microbial communities perform critical ecosystem services through the collective metabolic activities of numerous individual organisms. Most microbes use corrinoids, a structurally diverse family of cofactors related to vitamin B12. Corrinoid structure influences the growth of individual microbes, yet how these growth responses scale to the community level remains unknown. Analysis of metagenome-assembled genomes suggests corrinoids are supplied to the community by members of the archaeal and bacterial phyla Thermoproteota, Actinobacteria, and Proteobacteria. Corrinoids were found largely adhered to the soil matrix in a grassland soil, at levels exceeding those required by cultured bacteria. Enrichment cultures and soil microcosms seeded with different corrinoids showed distinct shifts in bacterial community composition, supporting the hypothesis that corrinoid structure can shape communities. Environmental context influenced both community and taxon-specific responses to specific corrinoids. These results implicate corrinoids as key determinants of soil microbiome structure and suggest that environmental micronutrient reservoirs promote community stability.
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Affiliation(s)
- Zachary F. Hallberg
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Alexa M. Nicolas
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Zoila I. Alvarez-Aponte
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Kenny C. Mok
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Ella T. Sieradzki
- Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Jennifer Pett-Ridge
- Lawrence Livermore National Laboratory, Livermore, CA, 94550 USA
- Innovative Genomics Institute, Berkeley, CA, 94720 USA
| | - Jillian F. Banfield
- Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, 94720 USA
- Innovative Genomics Institute, Berkeley, CA, 94720 USA
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720 USA
- Earth and Planetary Science, University of California, Berkeley, Berkeley, CA, 94720 USA
| | - Hans K. Carlson
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720 USA
| | - Mary K. Firestone
- Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA, 94720 USA
- Lawrence Berkeley National Laboratory, Berkeley, CA, 94720 USA
| | - Michiko E. Taga
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720 USA
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3
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Wienhausen G, Moraru C, Bruns S, Tran DQ, Sultana S, Wilkes H, Dlugosch L, Azam F, Simon M. Ligand cross-feeding resolves bacterial vitamin B 12 auxotrophies. Nature 2024; 629:886-892. [PMID: 38720071 DOI: 10.1038/s41586-024-07396-y] [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: 05/03/2021] [Accepted: 04/08/2024] [Indexed: 05/24/2024]
Abstract
Cobalamin (vitamin B12, herein referred to as B12) is an essential cofactor for most marine prokaryotes and eukaryotes1,2. Synthesized by a limited number of prokaryotes, its scarcity affects microbial interactions and community dynamics2-4. Here we show that two bacterial B12 auxotrophs can salvage different B12 building blocks and cooperate to synthesize B12. A Colwellia sp. synthesizes and releases the activated lower ligand α-ribazole, which is used by another B12 auxotroph, a Roseovarius sp., to produce the corrin ring and synthesize B12. Release of B12 by Roseovarius sp. happens only in co-culture with Colwellia sp. and only coincidently with the induction of a prophage encoded in Roseovarius sp. Subsequent growth of Colwellia sp. in these conditions may be due to the provision of B12 by lysed cells of Roseovarius sp. Further evidence is required to support a causative role for prophage induction in the release of B12. These complex microbial interactions of ligand cross-feeding and joint B12 biosynthesis seem to be widespread in marine pelagic ecosystems. In the western and northern tropical Atlantic Ocean, bacteria predicted to be capable of salvaging cobinamide and synthesizing only the activated lower ligand outnumber B12 producers. These findings add new players to our understanding of B12 supply to auxotrophic microorganisms in the ocean and possibly in other ecosystems.
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Affiliation(s)
- Gerrit Wienhausen
- Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany.
- Scripps Institution of Oceanography, Marine Biology Research Division, University of California San Diego, La Jolla, CA, USA.
| | - Cristina Moraru
- Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
- Environmental Metagenomics, Research Center One Health Ruhr of the University Alliance Ruhr, Faculty of Chemistry, University of Duisburg-Essen, Essen, Germany
| | - Stefan Bruns
- Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Den Quoc Tran
- Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Sabiha Sultana
- Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Heinz Wilkes
- Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Leon Dlugosch
- Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
| | - Farooq Azam
- Scripps Institution of Oceanography, Marine Biology Research Division, University of California San Diego, La Jolla, CA, USA
| | - Meinhard Simon
- Institute for Chemistry and Biology of the Marine Environment (ICBM), School of Mathematics and Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany.
- Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Oldenburg, Germany.
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4
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Hesse E, O’Brien S. Ecological dependencies and the illusion of cooperation in microbial communities. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001442. [PMID: 38385784 PMCID: PMC10924460 DOI: 10.1099/mic.0.001442] [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: 11/24/2023] [Accepted: 02/09/2024] [Indexed: 02/23/2024]
Abstract
Ecological dependencies - where organisms rely on other organisms for survival - are a ubiquitous feature of life on earth. Multicellular hosts rely on symbionts to provide essential vitamins and amino acids. Legume plants similarly rely on nitrogen-fixing rhizobia to convert atmospheric nitrogen to ammonia. In some cases, dependencies can arise via loss-of-function mutations that allow one partner to benefit from the actions of another. It is common in microbiology to label ecological dependencies between species as cooperation - making it necessary to invoke cooperation-specific frameworks to explain the phenomenon. However, in many cases, such traits are not (at least initially) cooperative, because they are not selected for because of the benefits they confer on a partner species. In contrast, dependencies in microbial communities may originate from fitness benefits gained from genomic-streamlining (i.e. Black Queen Dynamics). Here, we outline how the Black Queen Hypothesis predicts the formation of metabolic dependencies via loss-of-function mutations in microbial communities, without needing to invoke any cooperation-specific explanations. Furthermore we outline how the Black Queen Hypothesis can act as a blueprint for true cooperation as well as discuss key outstanding questions in the field. The nature of interactions in microbial communities can predict the ability of natural communities to withstand and recover from disturbances. Hence, it is vital to gain a deeper understanding of the factors driving these dynamic interactions over evolutionary time.
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Affiliation(s)
- Elze Hesse
- College of Life and Environmental Science, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
| | - Siobhán O’Brien
- Moyne Institute of Preventive Medicine, Department of Microbiology, School of Genetics and Microbiology, Trinity College Dublin, Dublin 2, Ireland
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5
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Dupuis S, Lingappa UF, Mayali X, Sindermann ES, Chastain JL, Weber PK, Stuart R, Merchant SS. Scarcity of fixed carbon transfer in a model microbial phototroph-heterotroph interaction. THE ISME JOURNAL 2024; 18:wrae140. [PMID: 39046282 PMCID: PMC11316394 DOI: 10.1093/ismejo/wrae140] [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: 01/26/2024] [Revised: 05/29/2024] [Accepted: 07/23/2024] [Indexed: 07/25/2024]
Abstract
Although the green alga Chlamydomonas reinhardtii has long served as a reference organism, few studies have interrogated its role as a primary producer in microbial interactions. Here, we quantitatively investigated C. reinhardtii's capacity to support a heterotrophic microbe using the established coculture system with Mesorhizobium japonicum, a vitamin B12-producing α-proteobacterium. Using stable isotope probing and nanoscale secondary ion mass spectrometry (nanoSIMS), we tracked the flow of photosynthetic fixed carbon and consequent bacterial biomass synthesis under continuous and diurnal light with single-cell resolution. We found that more 13C fixed by the alga was taken up by bacterial cells under continuous light, invalidating the hypothesis that the alga's fermentative degradation of starch reserves during the night would boost M. japonicum heterotrophy. 15NH4 assimilation rates and changes in cell size revealed that M. japonicum cells reduced new biomass synthesis in coculture with the alga but continued to divide-a hallmark of nutrient limitation often referred to as reductive division. Despite this sign of starvation, the bacterium still synthesized vitamin B12 and supported the growth of a B12-dependent C. reinhardtii mutant. Finally, we showed that bacterial proliferation could be supported solely by the algal lysis that occurred in coculture, highlighting the role of necromass in carbon cycling. Collectively, these results reveal the scarcity of fixed carbon in this microbial trophic relationship (particularly under environmentally relevant light regimes), demonstrate B12 exchange even during bacterial starvation, and underscore the importance of quantitative approaches for assessing metabolic coupling in algal-bacterial interactions.
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Affiliation(s)
- Sunnyjoy Dupuis
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, United States
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, United States
| | - Usha F Lingappa
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, United States
| | - Xavier Mayali
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, United States
| | - Eve S Sindermann
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, United States
| | - Jordan L Chastain
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, United States
- College of Chemistry, University of California, Berkeley, CA 94720, United States
| | - Peter K Weber
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, United States
| | - Rhona Stuart
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, United States
| | - Sabeeha S Merchant
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, United States
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, CA 94720, United States
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, United States
- Division of Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
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6
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Hallberg ZF, Nicolas AM, Alvarez-Aponte ZI, Mok KC, Sieradzki ET, Pett-Ridge J, Banfield JF, Carlson HK, Firestone MK, Taga ME. Soil microbial community response to corrinoids is shaped by a natural reservoir of vitamin B12. THE ISME JOURNAL 2024; 18:wrae094. [PMID: 38832716 PMCID: PMC11287211 DOI: 10.1093/ismejo/wrae094] [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: 03/01/2024] [Revised: 04/30/2024] [Accepted: 06/03/2024] [Indexed: 06/05/2024]
Abstract
Soil microbial communities perform critical ecosystem services through the collective metabolic activities of numerous individual organisms. Most microbes use corrinoids, a structurally diverse family of cofactors related to vitamin B12. Corrinoid structure influences the growth of individual microbes, yet how these growth responses scale to the community level remains unknown. Analysis of metagenome-assembled genomes suggests that corrinoids are supplied to the community by members of the archaeal and bacterial phyla Thermoproteota, Actinobacteria, and Proteobacteria. Corrinoids were found largely adhered to the soil matrix in a grassland soil, at levels exceeding those required by cultured bacteria. Enrichment cultures and soil microcosms seeded with different corrinoids showed distinct shifts in bacterial community composition, supporting the hypothesis that corrinoid structure can shape communities. Environmental context influenced both community- and taxon-specific responses to specific corrinoids. These results implicate corrinoids as key determinants of soil microbiome structure and suggest that environmental micronutrient reservoirs promote community stability.
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Affiliation(s)
- Zachary F Hallberg
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, United States
| | - Alexa M Nicolas
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, United States
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA 94720, United States
| | - Zoila I Alvarez-Aponte
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, United States
| | - Kenny C Mok
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, United States
| | - Ella T Sieradzki
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA 94720, United States
| | - Jennifer Pett-Ridge
- Physical & Life Science Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550, United States
- Innovative Genomics Institute, University of California Berkeley, Berkeley, CA 94720, United States
| | - Jillian F Banfield
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA 94720, United States
- Innovative Genomics Institute, University of California Berkeley, Berkeley, CA 94720, United States
- Division of Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
- Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA 94720, United States
- Earth & Environmental Sciences Area, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
| | - Hans K Carlson
- Division of Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
| | - Mary K Firestone
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA 94720, United States
- Division of Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, United States
| | - Michiko E Taga
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, United States
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7
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Pherribo GJ, Taga ME. Bacteriophage-mediated lysis supports robust growth of amino acid auxotrophs. THE ISME JOURNAL 2023; 17:1785-1788. [PMID: 37322284 PMCID: PMC10504361 DOI: 10.1038/s41396-023-01452-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/31/2023] [Accepted: 06/02/2023] [Indexed: 06/17/2023]
Abstract
Microbial communities host many auxotrophs-organisms unable to synthesize one or more metabolites required for their growth. Auxotrophy is thought to confer an evolutionary advantage, yet auxotrophs must rely on other organisms that produce the metabolites they require. The mechanisms of metabolite provisioning by "producers" remain unknown. In particular, it is unclear how metabolites such as amino acids and cofactors, which are found inside the cell, are released by producers to become available to auxotrophs. Here, we explore metabolite secretion and cell lysis as two distinct possible mechanisms that result in the release of intracellular metabolites from producer cells. We measured the extent to which secretion or lysis of Escherichia coli and Bacteroides thetaiotaomicron amino acid producers can support the growth of engineered Escherichia coli amino acid auxotrophs. We found that cell-free supernatants and mechanically lysed cells provide minimal levels of amino acids to auxotrophs. In contrast, bacteriophage lysates of the same producer bacteria can support as many as 47 auxotroph cells per lysed producer cell. Each phage lysate released distinct levels of different amino acids, suggesting that in a microbial community the collective lysis of many different hosts by multiple phages could contribute to the availability of an array of intracellular metabolites for use by auxotrophs. Based on these results, we speculate that viral lysis could be a dominant mechanism of provisioning of intracellular metabolites that shapes microbial community structure.
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Affiliation(s)
- Gordon J Pherribo
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Michiko E Taga
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA, 94720, USA.
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8
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Abstract
The metabolism of a bacterial cell stretches beyond its boundaries, often connecting with the metabolism of other cells to form extended metabolic networks that stretch across communities, and even the globe. Among the least intuitive metabolic connections are those involving cross-feeding of canonically intracellular metabolites. How and why are these intracellular metabolites externalized? Are bacteria simply leaky? Here I consider what it means for a bacterium to be leaky, and I review mechanisms of metabolite externalization from the context of cross-feeding. Despite common claims, diffusion of most intracellular metabolites across a membrane is unlikely. Instead, passive and active transporters are likely involved, possibly purging excess metabolites as part of homeostasis. Re-acquisition of metabolites by a producer limits the opportunities for cross-feeding. However, a competitive recipient can stimulate metabolite externalization and initiate a positive-feedback loop of reciprocal cross-feeding.
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Affiliation(s)
- James B McKinlay
- Department of Biology, Indiana University, Bloomington, Indiana, USA;
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9
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Vazquez-Munoz R, Thompson A, Sobue T, Dongari-Bagtzoglou A. A prebiotic diet modulates the oral microbiome composition and results in the attenuation of oropharyngeal candidiasis in mice. Microbiol Spectr 2023; 11:e0173423. [PMID: 37671879 PMCID: PMC10580959 DOI: 10.1128/spectrum.01734-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 07/06/2023] [Indexed: 09/07/2023] Open
Abstract
Oral bacteria can influence the ability of Candida albicans to cause oropharyngeal candidiasis (OPC). We recently reported that a Lactobacillus johnsonii-enriched oral microbiota reduced C. albicans virulence in an immunosuppressed OPC mouse model. As a follow-up, in this work, we aimed to enrich the resident oral Lactobacillus communities with a prebiotic diet to further assess their effect on the severity of OPC. We tested the effect of a prebiotic xylo-oligosaccharides (XOS)-enriched diet in the oral global bacterial composition and severity of OPC. We assessed changes in the oral microbiome composition via 16S-rRNA gene high-throughput sequencing, validated by qPCR. The impact of the prebiotic diet on Candida infection was assessed by quantifying changes in oral fungal and bacterial biomass and scoring tongue lesions. Contrary to expectations, oral Lactobacillus communities were not enriched by the XOS-supplemented diet. Yet, XOS modulated the oral microbiome composition, increasing Bifidobacterium abundance and reducing enterococci and staphylococci. In the OPC model, the XOS diet attenuated Candida virulence and bacterial dysbiosis, increasing lactobacilli and reducing enterococci on the oral mucosa. We conclude that XOS attenuates Candida virulence by promoting a bacterial microbiome structure more resilient to Candida infection. IMPORTANCE This is the first study on the effects of a prebiotic diet on the oral mucosal bacterial microbiome and an oropharyngeal candidiasis (OPC) mouse model. We found that xylo-oligosaccharides change the oral bacterial community composition and attenuate OPC. Our results contribute to the understanding of the impact of the oral bacterial communities on Candida virulence.
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Affiliation(s)
- Roberto Vazquez-Munoz
- Department of General Dentistry, The University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Angela Thompson
- Department of General Dentistry, The University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Takanori Sobue
- Department of General Dentistry, The University of Connecticut Health Center, Farmington, Connecticut, USA
| | - Anna Dongari-Bagtzoglou
- Department of General Dentistry, The University of Connecticut Health Center, Farmington, Connecticut, USA
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10
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Pherribo GJ, Taga ME. Bacteriophage-mediated lysis supports robust growth of amino acid auxotrophs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.28.530524. [PMID: 36909566 PMCID: PMC10002711 DOI: 10.1101/2023.02.28.530524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
The majority of microbes are auxotrophs - organisms unable to synthesize one or more metabolites required for their growth. Auxotrophy is thought to confer an evolutionary advantage, yet auxotrophs must rely on other organisms that produce the metabolites they require. The mechanisms of metabolite provisioning by "producers" remain unknown. In particular, it is unclear how metabolites such as amino acids and cofactors, which are found inside the cell, are released by producers to become available to auxotrophs. Here, we explore metabolite secretion and cell lysis as two distinct possible mechanisms that result in release of intracellular metabolites from producer cells. We measured the extent to which secretion or lysis of Escherichia coli and Bacteroides thetaiotaomicron amino acid producers can support the growth of engineered Escherichia coli amino acid auxotrophs. We found that cell-free supernatants and mechanically lysed cells provide minimal levels of amino acids to auxotrophs. In contrast, bacteriophage lysates of the same producer bacteria can support as many as 47 auxotroph cells per lysed producer cell. Each phage lysate released distinct levels of different amino acids, suggesting that in a microbial community the collective lysis of many different hosts by multiple phages could contribute to the availability of an array of intracellular metabolites for use by auxotrophs. Based on these results, we speculate that viral lysis could be a dominant mechanism of provisioning of intracellular metabolites that shapes microbial community structure.
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Affiliation(s)
- Gordon J. Pherribo
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720 U.S.A
| | - Michiko E. Taga
- Department of Plant & Microbial Biology, University of California, Berkeley, Berkeley, CA 94720 U.S.A
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11
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Classifying Interactions in a Synthetic Bacterial Community Is Hindered by Inhibitory Growth Medium. mSystems 2022; 7:e0023922. [PMID: 36197097 PMCID: PMC9600862 DOI: 10.1128/msystems.00239-22] [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] [Indexed: 12/24/2022] Open
Abstract
Predicting the fate of a microbial community and its member species relies on understanding the nature of their interactions. However, designing simple assays that distinguish between interaction types can be challenging. Here, we performed spent medium assays based on the predictions of a mathematical model to decipher the interactions among four bacterial species: Agrobacterium tumefaciens, Comamonas testosteroni, Microbacterium saperdae, and Ochrobactrum anthropi. While most experimental results matched model predictions, the behavior of C. testosteroni did not: its lag phase was reduced in the pure spent media of A. tumefaciens and M. saperdae but prolonged again when we replenished our growth medium. Further experiments showed that the growth medium actually delayed the growth of C. testosteroni, leading us to suspect that A. tumefaciens and M. saperdae could alleviate this inhibitory effect. There was, however, no evidence supporting such "cross-detoxification," and instead, we identified metabolites secreted by A. tumefaciens and M. saperdae that were then consumed or "cross-fed" by C. testosteroni, shortening its lag phase. Our results highlight that even simple, defined growth media can have inhibitory effects on some species and that such negative effects need to be included in our models. Based on this, we present new guidelines to correctly distinguish between different interaction types such as cross-detoxification and cross-feeding. IMPORTANCE Communities of microbes colonize virtually every place on earth. Ultimately, we strive to predict and control how these communities behave, for example, if they reside in our guts and make us sick. But precise control is impossible unless we can identify exactly how their member species interact with one another. To find a systematic way to measure interactions, we started very simply with a small community of four bacterial species and carefully designed experiments based on a mathematical model. This first attempt accurately mapped out interactions for all species except one. By digging deeper, we understood that our method failed for that species as it was suffering in the growth medium that we chose. A revised model that considered that growth media can be harmful could then make more accurate predictions. What we have learned with these four species can now be applied to decipher interactions in larger communities.
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12
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Giri S, Yousif G, Shitut S, Oña L, Kost C. Prevalent emergence of reciprocity among cross-feeding bacteria. ISME COMMUNICATIONS 2022; 2:71. [PMID: 37938764 PMCID: PMC9723789 DOI: 10.1038/s43705-022-00155-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 06/15/2022] [Accepted: 07/05/2022] [Indexed: 05/25/2023]
Abstract
Explaining the de novo evolution of obligate cooperative cross-feeding interactions among bacteria is a fundamental problem. A critical step during this process is the emergence of reciprocity among two interaction partners, because a mutually beneficial exchange of metabolic byproducts can subsequently favour the evolution of cooperative cross-feeding. However, so far, the propensity with which unidirectional cross-feeding interactions transition into bidirectional interactions remains unknown. To address this issue, we systematically cocultured four amino acid auxotrophic genotypes of two bacterial species with potential amino acid donors belonging to 25 different bacterial species. Surprisingly, the results of this experiment revealed that in around 40% of all cases analysed, both the auxotrophic recipient and the metabolically autonomous donor gained a significant growth advantage in coculture. Subsequent experiments clarified that the auxotrophy-causing mutation did not induce the growth-enhancing effect of recipients, but that it was rather due to a generally high propensity of different species to engage in synergistic metabolic interactions. Together, these findings show that reciprocity commonly emerges spontaneously in unidirectional cross-feeding interactions, thus paving the way for the evolution of even tighter metabolic interactions.
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Affiliation(s)
- Samir Giri
- Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, 07745, Jena, Germany.
- Department of Ecology, School of Biology/Chemistry, Osnabrück University, 49076, Osnabrück, Germany.
- Genome Biology Unit, European Molecular Biology Laboratory, 69117, Heidelberg, Germany.
| | - Ghada Yousif
- Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, 07745, Jena, Germany
- Department of Ecology, School of Biology/Chemistry, Osnabrück University, 49076, Osnabrück, Germany
- Department of Botany and Microbiology, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt
| | - Shraddha Shitut
- Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, 07745, Jena, Germany
- Department of Ecology, School of Biology/Chemistry, Osnabrück University, 49076, Osnabrück, Germany
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117, Heidelberg, Germany
| | - Leonardo Oña
- Department of Ecology, School of Biology/Chemistry, Osnabrück University, 49076, Osnabrück, Germany
| | - Christian Kost
- Experimental Ecology and Evolution Research Group, Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, 07745, Jena, Germany.
- Department of Ecology, School of Biology/Chemistry, Osnabrück University, 49076, Osnabrück, Germany.
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13
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Abstract
All organisms rely on complex metabolites such as amino acids, nucleotides, and cofactors for essential metabolic processes. Some microbes synthesize these fundamental ingredients of life de novo, while others rely on uptake to fulfill their metabolic needs. Although certain metabolic processes are inherently "leaky," the mechanisms enabling stable metabolite provisioning among microbes in the absence of a host remain largely unclear. In particular, how can metabolite provisioning among free-living bacteria be maintained under the evolutionary pressure to economize resources? Salvaging, the process of "recycling and reusing," can be a metabolically efficient route to obtain access to required resources. Here, we show experimentally how precursor salvaging in engineered Escherichia coli populations can lead to stable, long-term metabolite provisioning. We find that salvaged cobamides (vitamin B12 and related enzyme cofactors) are readily made available to nonproducing population members, yet salvagers are strongly protected from overexploitation. We also describe a previously unnoted benefit of precursor salvaging, namely, the removal of the nonfunctional, proliferation-inhibiting precursor. As long as compatible precursors are present, any microbe possessing the terminal steps of a biosynthetic process can, in principle, forgo de novo biosynthesis in favor of salvaging. Consequently, precursor salvaging likely represents a potent, yet overlooked, alternative to de novo biosynthesis for the acquisition and provisioning of metabolites in free-living bacterial populations. IMPORTANCE Recycling gives new life to old things. Bacteria have the ability to recycle and reuse complex molecules they encounter in their environment to fulfill their basic metabolic needs in a resource-efficient way. By studying the salvaging (recycling and reusing) of vitamin B12 precursors, we found that metabolite salvaging can benefit others and provide stability to a bacterial community at the same time. Salvagers of vitamin B12 precursors freely share the result of their labor yet cannot be outcompeted by freeloaders, likely because salvagers retain preferential access to the salvaging products. Thus, salvaging may represent an effective, yet overlooked, mechanism of acquiring and provisioning nutrients in microbial populations.
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14
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Lajoie G, Parfrey LW. Beyond specialization: re-examining routes of host influence on symbiont evolution. Trends Ecol Evol 2022; 37:590-598. [PMID: 35466020 DOI: 10.1016/j.tree.2022.03.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 03/15/2022] [Accepted: 03/20/2022] [Indexed: 11/17/2022]
Abstract
Our understanding of host influence on microbial evolution has focused on symbiont specialization and the genomic streamlining that often accompanies it. However, a vast diversity of symbiotic lineages facultatively interact with hosts or associate with multiple hosts. Yet, there are no clear expectations for how host association influences the niche of these symbionts or their evolution. Here, we discuss how weak or variable selection on microbial symbiotic associations, horizontal transmission, and low costs of adaptation to novel host habitats are predicted to promote the expansion or maintenance of microbial niches. This broad perspective will aid in developing better and more general predictions for evolution in microbial symbioses.
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Affiliation(s)
- Geneviève Lajoie
- Botany Department, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada, V6T 1Z4.
| | - Laura Wegener Parfrey
- Botany Department, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada, V6T 1Z4
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15
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Chodkowski JL, Shade A. Exometabolite Dynamics over Stationary Phase Reveal Strain-Specific Responses. mSystems 2020; 5:e00493-20. [PMID: 33361318 PMCID: PMC7762789 DOI: 10.1128/msystems.00493-20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 11/25/2020] [Indexed: 11/20/2022] Open
Abstract
Microbial exponential growth is expected to occur infrequently in environments that have long periods of nutrient starvation punctuated by short periods of high nutrient flux. These conditions likely impose nongrowth states for microbes. However, nongrowth states are uncharacterized for the majority of environmental bacteria, especially in regard to exometabolite production. We compared exometabolites produced over stationary phase across three environmental bacteria: Burkholderia thailandensis E264 (ATCC 700388), Chromobacterium violaceum ATCC 31532, and Pseudomonas syringae pv. tomato DC3000 (ATCC BAA-871). We grew each strain in monoculture and investigated exometabolite dynamics from mid-exponential to stationary phases. We focused on exometabolites that were released into the medium and accumulated over 45 h, including approximately 20 h of stationary phase. We also analyzed transcripts (transcriptome sequencing [RNA-seq]) to interpret exometabolite output. We found that the majority of exometabolites released were strain specific, with a subset of identified exometabolites involved in both central and secondary metabolism. Transcript analysis supported that exometabolites were released from intact cells, as various transporters had either increased or consistent transcripts through time. Interestingly, we found that succinate was one of the most abundant identifiable exometabolites for all strains and that each strain rerouted their metabolic pathways involved in succinate production during stationary phase. These results show that nongrowth states can be metabolically dynamic and that environmental bacteria can enrich a minimal environment with diverse chemical compounds as a consequence of growth and postgrowth maintenance in stationary phase. This work provides insights into microbial community interactions via exometabolites under conditions of growth cessation or limitation.IMPORTANCE Nongrowth states are common for bacteria that live in environments that are densely populated and predominantly nutrient exhausted, and yet these states remain largely uncharacterized in cellular metabolism and metabolite output. Here, we investigated and compared stationary-phase exometabolites and RNA transcripts for each of three environmental bacterial strains. We observed that diverse exometabolites were produced and provide evidence that these exometabolites accumulate over time through release by intact cells. Additionally, each bacterial strain had a characteristic exometabolite profile and exhibited dynamics in exometabolite composition. This work affirms that stationary phase is metabolically dynamic, with each strain tested creating a unique chemical signature in the extracellular space and altering metabolism in stationary phase. These findings set the stage for understanding how bacterial populations can support surrounding neighbors in environments with prolonged nutrient exhaustion through exometabolite-mediated interspecies interactions.
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Affiliation(s)
- John L Chodkowski
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
| | - Ashley Shade
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, USA
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan, USA
- Program in Ecology, Evolution, and Behavior, Michigan State University, East Lansing, Michigan, USA
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