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Svendsen PB, Henriksen NNSE, Jarmusch SA, Andersen AJC, Smith K, Selsmark MW, Zhang SD, Schostag MD, Gram L. Co-existence of two antibiotic-producing marine bacteria: Pseudoalteromonas piscicida reduce gene expression and production of the antibacterial compound, tropodithietic acid, in Phaeobacter sp. Appl Environ Microbiol 2024; 90:e0058824. [PMID: 39136490 PMCID: PMC11409694 DOI: 10.1128/aem.00588-24] [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: 03/26/2024] [Accepted: 07/16/2024] [Indexed: 09/19/2024] Open
Abstract
Many bacteria co-exist and produce antibiotics, yet we know little about how they cope and occupy the same niche. The purpose of the present study was to determine if and how two potent antibiotic-producing marine bacteria influence the secondary metabolome of each other. We established an agar- and broth-based system allowing co-existence of a Phaeobacter species and Pseudoalteromonas piscicida that, respectively, produce tropodithietic acid (TDA) and bromoalterochromides (BACs). Co-culturing of Phaeobacter sp. strain A36a-5a on Marine Agar with P. piscicida strain B39bio caused a reduction of TDA production in the Phaeobacter colony. We constructed a transcriptional gene reporter fusion in the tdaC gene in the TDA biosynthetic pathway in Phaeobacter and demonstrated that the reduction of TDA by P. piscicida was due to the suppression of the TDA biosynthesis. A stable liquid co-cultivation system was developed, and the expression of tdaC in Phaeobacter was reduced eightfold lower (per cell) in the co-culture compared to the monoculture. Mass spectrometry imaging of co-cultured colonies revealed a reduction of TDA and indicated that BACs diffused into the Phaeobacter colony. BACs were purified from Pseudoalteromonas; however, when added as pure compounds or a mixture they did not influence TDA production. In co-culture, the metabolome was dominated by Pseudoalteromonas features indicating that production of other Phaeobacter compounds besides TDA was reduced. In conclusion, co-existence of two antibiotic-producing bacteria may be allowed by one causing reduction in the antagonistic potential of the other. The reduction (here of TDA) was not caused by degradation but by a yet uncharacterized mechanism allowing Pseudoalteromonas to reduce expression of the TDA biosynthetic pathway.IMPORTANCEThe drug potential of antimicrobial secondary metabolites has been the main driver of research into these compounds. However, in recent years, their natural role in microbial systems and microbiomes has become important to determine the assembly and development of microbiomes. Herein, we demonstrate that two potent antibiotic-producing bacteria can co-exist, and one mechanism allowing the co-existence is the specific reduction of antibiotic production in one bacterium by the other. Understanding the molecular mechanisms in complex interactions provides insights for applied uses, such as when developing TDA-producing bacteria for use as biocontrol in aquaculture.
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Affiliation(s)
- Peter Bing Svendsen
- Department of Biotechnology and Biomedicine, Center for Microbial Secondary Metabolites, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Nathalie N. S. E. Henriksen
- Department of Biotechnology and Biomedicine, Center for Microbial Secondary Metabolites, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Scott A. Jarmusch
- Department of Biotechnology and Biomedicine, Center for Microbial Secondary Metabolites, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Aaron J. C. Andersen
- Department of Biotechnology and Biomedicine, Center for Microbial Secondary Metabolites, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Kirsty Smith
- Department of Biotechnology and Biomedicine, Center for Microbial Secondary Metabolites, Technical University of Denmark, Kgs. Lyngby, Denmark
- Department of Chemistry, University of Aberdeen, King’s College, Aberdeen, United Kingdom
| | - Marcus Weichel Selsmark
- Department of Biotechnology and Biomedicine, Center for Microbial Secondary Metabolites, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Sheng-Da Zhang
- Department of Biotechnology and Biomedicine, Center for Microbial Secondary Metabolites, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Morten D. Schostag
- Department of Biotechnology and Biomedicine, Center for Microbial Secondary Metabolites, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Lone Gram
- Department of Biotechnology and Biomedicine, Center for Microbial Secondary Metabolites, Technical University of Denmark, Kgs. Lyngby, Denmark
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Roager L, Kempen PJ, Bentzon-Tilia M, Sonnenschein EC, Gram L. Impact of host species on assembly, composition, and functional profiles of phycosphere microbiomes. mSystems 2024; 9:e0058324. [PMID: 39082797 PMCID: PMC11334532 DOI: 10.1128/msystems.00583-24] [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: 04/24/2024] [Accepted: 07/01/2024] [Indexed: 08/21/2024] Open
Abstract
Microalgal microbiomes play vital roles in the growth and health of their host, however, their composition and functions remain only partially characterized, especially across microalgal phyla. In this study, a natural seawater microbiome was introduced to three distinct, axenic species of microalgae, the haptophyte Isochrysis galbana, the chlorophyte Tetraselmis suecica, and the diatom Conticribra weissflogii (previously Thalassiosira), and its divergence and assembly under constant illumination was monitored over 49 days using 16S rRNA amplicon and metagenomic analyses. The microbiomes had a high degree of host specificity in terms of taxonomic composition and potential functions, including CAZymes profiles. Rhodobacteraceae and Flavobacteriaceae families were abundant across all microalgal hosts, but I. galbana microbiomes diverged further from T. suecica and C. weissflogii microbiomes. I. galbana microbiomes had a much higher relative abundance of Flavobacteriaceae, whereas the two other algal microbiomes had higher relative abundances of Rhodobacteraceae. This could be due to the bacterivorous mixotrophic nature of I. galbana affecting the carbohydrate composition available to the microbiomes, which was supported by the CAZymes profile of I. galbana microbiomes diverging further from those of T. suecica and C. weissflogii microbiomes. Finally, the presence of denitrification and other anaerobic pathways was found exclusively in the microbiomes of C. weissflogii, which we speculate could be a result of anoxic microenvironments forming in aggregates formed by this diatom during the experiment. These results underline the significant role of the microalgal host species on microbiome composition and functional profiles along with other factors, such as the trophic mode of the microalgal host. IMPORTANCE As the main primary producers of the oceans, microalgae serve as cornerstones of the ecosystems they are part of. Additionally, they are increasingly used for biotechnological purposes such as the production of nutraceuticals, pigments, and antioxidants. Since the bacterial microbiomes of microalgae can affect their hosts in beneficial and detrimental ways, understanding these microbiomes is crucial to both the ecological and applied roles of microalgae. The present study advances the understanding of microalgal microbiome assembly, composition, and functionality across microalgal phyla, which may inform the modeling and engineering of microalgal microbiomes for biotechnological purposes.
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Affiliation(s)
- Line Roager
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Paul J. Kempen
- DTU Nanolab, National Center for Nano Fabrication and Characterization, Technical University of Denmark, Kgs. Lyngby, Denmark
- Department of Health Technology, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Mikkel Bentzon-Tilia
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Eva C. Sonnenschein
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Lone Gram
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
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Isaac A, Mohamed AR, Amin SA. Rhodobacteraceae are key players in microbiome assembly of the diatom Asterionellopsis glacialis. Appl Environ Microbiol 2024; 90:e0057024. [PMID: 38809046 PMCID: PMC11218658 DOI: 10.1128/aem.00570-24] [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: 03/29/2024] [Accepted: 05/05/2024] [Indexed: 05/30/2024] Open
Abstract
The complex interactions between bacterioplankton and phytoplankton have prompted numerous studies that investigate phytoplankton microbiomes with the aim of characterizing beneficial or opportunistic taxa and elucidating core bacterial members. Oftentimes, this knowledge is garnered through 16S rRNA gene profiling of microbiomes from phytoplankton isolated across spatial and temporal scales, yet these studies do not offer insight into microbiome assembly and structuring. In this study, we aimed to identify taxa central to structuring and establishing the microbiome of the ubiquitous diatom Asterionellopsis glacialis. We introduced a diverse environmental bacterial community to A. glacialis in nutrient-rich or nutrient-poor media in a continuous dilution culture setup and profiled the bacterial community over 7 days. 16S rRNA amplicon sequencing showed that cyanobacteria (Coleofasciculaceae) and Rhodobacteraceae dominate the microbiome early on and maintain a persistent association throughout the experiment. Differential abundance, co-abundance networks, and differential association analyses revealed that specific members of the family Rhodobacteraceae, particularly Sulfitobacter amplicon sequence variants, become integral members in microbiome assembly. In the presence of the diatom, Sulfitobacter species and other Rhodobacteraceae developed positive associations with taxa that are typically in high abundance in marine ecosystems (Pelagibacter and Synechococcus), leading to restructuring of the microbiome compared to diatom-free controls. These positive associations developed predominantly under oligotrophic conditions, highlighting the importance of investigating phytoplankton microbiomes in as close to natural conditions as possible to avoid biases that develop under routine laboratory conditions. These findings offer further insight into phytoplankton-bacteria interactions and illustrate the importance of Rhodobacteraceae, not merely as phytoplankton symbionts but as key taxa involved in microbiome assembly. IMPORTANCE Most, if not all, microeukaryotic organisms harbor an associated microbial community, termed the microbiome. The microscale interactions that occur between these partners have global-scale consequences, influencing marine primary productivity, carbon cycling, and harmful algal blooms to name but a few. Over the last decade, there has been a growing interest in the study of phytoplankton microbiomes, particularly within the context of bloom dynamics. However, long-standing questions remain regarding the process of phytoplankton microbiome assembly. The significance of our research is to tease apart the mechanism of microbiome assembly with a particular focus on identifying bacterial taxa, which may not merely be symbionts but architects of the phytoplankton microbiome. Our results strengthen the understanding of the ecological mechanisms that underpin phytoplankton-bacteria interactions in order to accurately predict marine ecosystem responses to environmental perturbations.
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Affiliation(s)
- Ashley Isaac
- Marine Microbiomics Lab, Biology Program, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
- Department of Molecular Ecology, Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Amin R. Mohamed
- Marine Microbiomics Lab, Biology Program, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Shady A. Amin
- Marine Microbiomics Lab, Biology Program, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
- Center for Genomics and Systems Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
- Mubadala ACCESS Center, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
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Nappi J, Goncalves P, Khan T, Majzoub ME, Grobler AS, Marzinelli EM, Thomas T, Egan S. Differential priority effects impact taxonomy and functionality of host-associated microbiomes. Mol Ecol 2023; 32:6278-6293. [PMID: 34995388 DOI: 10.1111/mec.16336] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/01/2021] [Accepted: 12/16/2021] [Indexed: 01/24/2023]
Abstract
Most multicellular eukaryotes host complex communities of microorganisms, but the factors that govern their assembly are poorly understood. The settlement of specific microorganisms may have a lasting impact on community composition, a phenomenon known as the priority effect. Priority effects of individual bacterial strains on a host's microbiome are, however, rarely studied and their impact on microbiome functionality remains unknown. We experimentally tested the effect of two bacterial strains (Pseudoalteromonas tunicata D2 and Pseudovibrio sp. D323) on the assembly and succession of the microbial communities associated with the green macroalga Ulva australis. Using 16S rRNA gene sequencing and qPCR, we found that both strains exert a priority effect, with strain D2 causing initially strong but temporary taxonomic changes and strain D323 causing weaker but consistent changes. Consistent changes were predominately facilitatory and included taxa that may benefit the algal host. Metagenome analyses revealed that the strains elicited both shared (e.g., depletion of type III secretion system genes) and unique (e.g., enrichment of antibiotic resistance genes) effects on the predicted microbiome functionality. These findings indicate strong idiosyncratic effects of colonizing bacteria on the structure and function of host-associated microbial communities. Understanding the idiosyncrasies in priority effects is key for the development of novel probiotics to improve host condition.
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Affiliation(s)
- Jadranka Nappi
- Centre of Marine Science and Innovation, School of Biological and Environmental Science, University of New South Wales, Sydney, NSW, Australia
| | - Priscila Goncalves
- Centre of Marine Science and Innovation, School of Biological and Environmental Science, University of New South Wales, Sydney, NSW, Australia
| | - Tahsin Khan
- Centre of Marine Science and Innovation, School of Biological and Environmental Science, University of New South Wales, Sydney, NSW, Australia
| | - Marwan E Majzoub
- Centre of Marine Science and Innovation, School of Biological and Environmental Science, University of New South Wales, Sydney, NSW, Australia
| | - Anna Sophia Grobler
- Centre of Marine Science and Innovation, School of Biological and Environmental Science, University of New South Wales, Sydney, NSW, Australia
| | - Ezequiel M Marzinelli
- Faculty of Science, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
- Singapore Centre for Environmental Life Sciences Engineering, Nanyang Technological University, Singapore, Singapore
- Sydney Institute of Marine Science, Mosman, NSW, Australia
| | - Torsten Thomas
- Centre of Marine Science and Innovation, School of Biological and Environmental Science, University of New South Wales, Sydney, NSW, Australia
| | - Suhelen Egan
- Centre of Marine Science and Innovation, School of Biological and Environmental Science, University of New South Wales, Sydney, NSW, Australia
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5
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Alker AT, Farrell MV, Aspiras AE, Dunbar TL, Fedoriouk A, Jones JE, Mikhail SR, Salcedo GY, Moore BS, Shikuma NJ. A modular plasmid toolkit applied in marine bacteria reveals functional insights during bacteria-stimulated metamorphosis. mBio 2023; 14:e0150223. [PMID: 37530556 PMCID: PMC10470607 DOI: 10.1128/mbio.01502-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 06/17/2023] [Indexed: 08/03/2023] Open
Abstract
A conspicuous roadblock to studying marine bacteria for fundamental research and biotechnology is a lack of modular synthetic biology tools for their genetic manipulation. Here, we applied, and generated new parts for, a modular plasmid toolkit to study marine bacteria in the context of symbioses and host-microbe interactions. To demonstrate the utility of this plasmid system, we genetically manipulated the marine bacterium Pseudoalteromonas luteoviolacea, which stimulates the metamorphosis of the model tubeworm, Hydroides elegans. Using these tools, we quantified constitutive and native promoter expression, developed reporter strains that enable the imaging of host-bacteria interactions, and used CRISPR interference (CRISPRi) to knock down a secondary metabolite and a host-associated gene. We demonstrate the broader utility of this modular system for testing the genetic tractability of marine bacteria that are known to be associated with diverse host-microbe symbioses. These efforts resulted in the successful conjugation of 12 marine strains from the Alphaproteobacteria and Gammaproteobacteria classes. Altogether, the present study demonstrates how synthetic biology strategies enable the investigation of marine microbes and marine host-microbe symbioses with potential implications for environmental restoration and biotechnology. IMPORTANCE Marine Proteobacteria are attractive targets for genetic engineering due to their ability to produce a diversity of bioactive metabolites and their involvement in host-microbe symbioses. Modular cloning toolkits have become a standard for engineering model microbes, such as Escherichia coli, because they enable innumerable mix-and-match DNA assembly and engineering options. However, such modular tools have not yet been applied to most marine bacterial species. In this work, we adapt a modular plasmid toolkit for use in a set of 12 marine bacteria from the Gammaproteobacteria and Alphaproteobacteria classes. We demonstrate the utility of this genetic toolkit by engineering a marine Pseudoalteromonas bacterium to study their association with its host animal Hydroides elegans. This work provides a proof of concept that modular genetic tools can be applied to diverse marine bacteria to address basic science questions and for biotechnology innovations.
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Affiliation(s)
- Amanda T. Alker
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Morgan V. Farrell
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Alpher E. Aspiras
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Tiffany L. Dunbar
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Andriy Fedoriouk
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Jeffrey E. Jones
- Department of Biology, San Diego State University, San Diego, California, USA
| | - Sama R. Mikhail
- Department of Biology, San Diego State University, San Diego, California, USA
| | | | - Bradley S. Moore
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, California, USA
| | - Nicholas J. Shikuma
- Department of Biology, San Diego State University, San Diego, California, USA
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Bech PK, Zhang SD, Henriksen NNSE, Bentzon-Tilia M, Strube ML, Gram L. The potential to produce tropodithietic acid by Phaeobacter inhibens affects the assembly of microbial biofilm communities in natural seawater. NPJ Biofilms Microbiomes 2023; 9:12. [PMID: 36959215 PMCID: PMC10036634 DOI: 10.1038/s41522-023-00379-3] [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: 04/08/2022] [Accepted: 03/10/2023] [Indexed: 03/25/2023] Open
Abstract
Microbial secondary metabolites play important roles in biotic interactions in microbial communities and yet, we do not understand how these compounds impact the assembly and development of microbial communities. To address the implications of microbial secondary metabolite production on biotic interactions in the assembly of natural seawater microbiomes, we constructed a model system where the assembly of a natural seawater biofilm community was influenced by the addition of the marine biofilm forming Phaeobacter inhibens that can produce the antibiotic secondary metabolite tropodithietic acid (TDA), or a mutant incapable of TDA production. Because of the broad antibiotic activity of TDA, we hypothesized that the potential of P. inhibens to produce TDA would strongly affect both biofilm and planktonic community assembly patterns. We show that 1.9 % of the microbial composition variance across both environments could be attributed to the presence of WT P. inhibens, and especially genera of the Bacteriodetes were increased by the presence of the TDA producer. Moreover, network analysis with inferred putative microbial interactions revealed that P. inhibens mainly displayed strong positive associations with genera of the Flavobacteriaceae and Alteromonadaceae, and that P. inhibens acts as a keystone OTU in the biofilm exclusively due to its potential to produce TDA. Our results demonstrate the potential impact of microbial secondary metabolites on microbial interactions and assembly dynamics of complex microbial communities.
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Affiliation(s)
| | - Sheng-Da Zhang
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | | | - Mikkel Bentzon-Tilia
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Mikael Lenz Strube
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Lone Gram
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark.
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Tropodithietic Acid, a Multifunctional Antimicrobial, Facilitates Adaption and Colonization of the Producer, Phaeobacter piscinae. mSphere 2023; 8:e0051722. [PMID: 36622251 PMCID: PMC9942592 DOI: 10.1128/msphere.00517-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In the marine environment, surface-associated bacteria often produce an array of antimicrobial secondary metabolites, which have predominantly been perceived as competition molecules. However, they may also affect other hallmarks of surface-associated living, such as motility and biofilm formation. Here, we investigate the ecological significance of an antibiotic secondary metabolite, tropodithietic acid (TDA), in the producing bacterium, Phaeobacter piscinae S26. We constructed a markerless in-frame deletion mutant deficient in TDA biosynthesis, S26ΔtdaB. Molecular networking demonstrated that other chemical sulfur-containing features, likely related to TDA, were also altered in the secondary metabolome. We found several changes in the physiology of the TDA-deficient mutant, ΔtdaB, compared to the wild type. Growth of the two strains was similar; however, ΔtdaB cells were shorter and more motile. Transcriptome and proteome profiling revealed an increase in gene expression and protein abundance related to a type IV secretion system, and to a prophage, and a gene transfer agent in ΔtdaB. All these systems may contribute to horizontal gene transfer (HGT), which may facilitate adaptation to novel niches. We speculate that once a TDA-producing population has been established in a new niche, the accumulation of TDA acts as a signal of successful colonization, prompting a switch to a sessile lifestyle. This would lead to a decrease in motility and the rate of HGT, while filamentous cells could form the base of a biofilm. In addition, the antibiotic properties of TDA may inhibit invading competing microorganisms. This points to a role of TDA in coordinating colonization and adaptation. IMPORTANCE Despite the broad clinical usage of microbial secondary metabolites with antibiotic activity, little is known about their role in natural microbiomes. Here, we studied the effect of production of the antibiotic tropodithietic acid (TDA) on the producing strain, Phaeobacter piscinae S26, a member of the Roseobacter group. We show that TDA affects several phenotypes of the producing strain, including motility, cell morphology, metal metabolism, and three horizontal gene transfer systems: a prophage, a type IV secretion system, and a gene transfer agent. Together, this indicates that TDA participates in coordinating the colonization process of the producer. TDA is thus an example of a multifunctional secondary metabolite that can mediate complex interactions in microbial communities. This work broadens our understanding of the ecological role that secondary metabolites have in microbial community dynamics.
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Alker AT, Aspiras AE, Dunbar TL, Farrell MV, Fedoriouk A, Jones JE, Mikhail SR, Salcedo GY, Moore BS, Shikuma NJ. A modular plasmid toolkit applied in marine Proteobacteria reveals functional insights during bacteria-stimulated metamorphosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.31.526474. [PMID: 36778221 PMCID: PMC9915575 DOI: 10.1101/2023.01.31.526474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A conspicuous roadblock to studying marine bacteria for fundamental research and biotechnology is a lack of modular synthetic biology tools for their genetic manipulation. Here, we applied, and generated new parts for, a modular plasmid toolkit to study marine bacteria in the context of symbioses and host-microbe interactions. To demonstrate the utility of this plasmid system, we genetically manipulated the marine bacterium Pseudoalteromonas luteoviolacea , which stimulates the metamorphosis of the model tubeworm, Hydroides elegans . Using these tools, we quantified constitutive and native promoter expression, developed reporter strains that enable the imaging of host-bacteria interactions, and used CRISPR interference (CRISPRi) to knock down a secondary metabolite and a host-associated gene. We demonstrate the broader utility of this modular system for rapidly creating and iteratively testing genetic tractability by modifying marine bacteria that are known to be associated with diverse host-microbe symbioses. These efforts enabled the successful transformation of twelve marine strains across two Proteobacteria classes, four orders and ten genera. Altogether, the present study demonstrates how synthetic biology strategies enable the investigation of marine microbes and marine host-microbe symbioses with broader implications for environmental restoration and biotechnology.
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9
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Henriksen NNSE, Schostag MD, Balder SR, Bech PK, Strube ML, Sonnenschein EC, Gram L. The ability of Phaeobacter inhibens to produce tropodithietic acid influences the community dynamics of a microalgal microbiome. ISME COMMUNICATIONS 2022; 2:109. [PMID: 37938341 PMCID: PMC9723703 DOI: 10.1038/s43705-022-00193-6] [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: 01/14/2022] [Revised: 10/14/2022] [Accepted: 10/19/2022] [Indexed: 11/09/2023]
Abstract
Microbial secondary metabolites facilitate microbial interactions and are crucial for understanding the complexity of microbial community dynamics. The purpose of the present study was to determine how a secondary metabolite producing marine bacteria or its metabolite deficient mutant affected the microbiome of the marine microalgae Tetraselmis suecica during a 70 day long co-evolution experiment. Using 16S rRNA gene amplicon sequencing, we found that neither the tropodithietic acid (TDA)-producing Phaeobacter inhibens wildtype nor the TDA-deficient mutant had major impacts on the community composition. However, a subset of strains, displayed temporally different relative abundance trajectories depending on the presence of P. inhibens. In particular, a Winogradskyella strain displayed temporal higher relative abundance when the TDA-producing wildtype was present. Numbers of the TDA-producing wildtype were reduced significantly more than those of the mutant over time indicating that TDA production was not an advantage. In communities without the P. inhibens wildtype strain, an indigenous population of Phaeobacter increased over time, indicating that indigenous Phaeobacter populations cannot co-exist with the TDA-producing wildtype. Despite that TDA was not detected chemically, we detected transcripts of the tdaC gene indicating that TDA could be produced in the microbial community associated with the algae. Our work highlights the importance of deciphering longitudinal strain dynamics when addressing the ecological effect of secondary metabolites in a relevant natural community.
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Affiliation(s)
| | - Morten Dencker Schostag
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads Bldg. 221, DK-2800 Kgs, Lyngby, Denmark
| | - Simone Rosen Balder
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads Bldg. 221, DK-2800 Kgs, Lyngby, Denmark
| | - Pernille Kjersgaard Bech
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads Bldg. 221, DK-2800 Kgs, Lyngby, Denmark
| | - Mikael Lenz Strube
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads Bldg. 221, DK-2800 Kgs, Lyngby, Denmark
| | - Eva Christina Sonnenschein
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads Bldg. 221, DK-2800 Kgs, Lyngby, Denmark
- Department of Biosciences, Swansea University, Singleton Park, SA2 8PP, Swansea, United Kingdom
| | - Lone Gram
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads Bldg. 221, DK-2800 Kgs, Lyngby, Denmark.
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10
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Zhang Y, Gallant É, Park JD, Seyedsayamdost MR. The Small-Molecule Language of Dynamic Microbial Interactions. Annu Rev Microbiol 2022; 76:641-660. [PMID: 35679616 PMCID: PMC10171915 DOI: 10.1146/annurev-micro-042722-091052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although microbes are routinely grown in monocultures in the laboratory, they are almost never encountered as single species in the wild. Our ability to detect and identify new microorganisms has advanced significantly in recent years, but our understanding of the mechanisms that mediate microbial interactions has lagged behind. What makes this task more challenging is that microbial alliances can be dynamic, consisting of multiple phases. The transitions between phases, and the interactions in general, are often mediated by a chemical language consisting of small molecules, also referred to as secondary metabolites or natural products. In this microbial lexicon, the molecules are like words and through their effects on recipient cells they convey meaning. The current review highlights three dynamic microbial interactions in which some of the words and their meanings have been characterized, especially those that mediate transitions in selected multiphasic associations. These systems provide insights into the principles that govern microbial symbioses and a playbook for interrogating similar associations in diverse ecological niches. 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)
- Yifan Zhang
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA; ,
| | - Étienne Gallant
- Department of Chemistry, Princeton University, Princeton, New Jersey, USA; ,
| | - Jong-Duk Park
- Department of Chemistry, Princeton University, Princeton, New Jersey, USA; ,
| | - Mohammad R Seyedsayamdost
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA; , .,Department of Chemistry, Princeton University, Princeton, New Jersey, USA; ,
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Henriksen NNSE, Lindqvist LL, Wibowo M, Sonnenschein EC, Bentzon-Tilia M, Gram L. Role is in the eye of the beholder-the multiple functions of the antibacterial compound tropodithietic acid produced by marine Rhodobacteraceae. FEMS Microbiol Rev 2022; 46:fuac007. [PMID: 35099011 PMCID: PMC9075582 DOI: 10.1093/femsre/fuac007] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 01/24/2022] [Accepted: 01/27/2022] [Indexed: 11/13/2022] Open
Abstract
Many microbial secondary metabolites have been studied for decades primarily because of their antimicrobial properties. However, several of these metabolites also possess nonantimicrobial functions, both influencing the physiology of the producer and their ecological neighbors. An example of a versatile bacterial secondary metabolite with multiple functions is the tropone derivative tropodithietic acid (TDA). TDA is a broad-spectrum antimicrobial compound produced by several members of the Rhodobacteraceae family, a major marine bacterial lineage, within the genera Phaeobacter, Tritonibacter, and Pseudovibrio. The production of TDA is governed by the mode of growth and influenced by the availability of nutrient sources. The antibacterial effect of TDA is caused by disruption of the proton motive force of target microorganisms and, potentially, by its iron-chelating properties. TDA also acts as a signaling molecule, affecting gene expression in other bacteria, and altering phenotypic traits such as motility, biofilm formation, and antibiotic production in the producer. In microbial communities, TDA-producing bacteria cause a reduction of the relative abundance of closely related species and some fast-growing heterotrophic bacteria. Here, we summarize the current understanding of the chemical ecology of TDA, including the environmental niches of TDA-producing bacteria, and the molecular mechanisms governing the function and regulation of TDA.
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Affiliation(s)
- Nathalie N S E Henriksen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts, Plads Bldg. 221, DK-2800 Kgs. Lyngby, Denmark
| | - Laura L Lindqvist
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts, Plads Bldg. 221, DK-2800 Kgs. Lyngby, Denmark
| | - Mario Wibowo
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts, Plads Bldg. 221, DK-2800 Kgs. Lyngby, Denmark
| | - Eva C Sonnenschein
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts, Plads Bldg. 221, DK-2800 Kgs. Lyngby, Denmark
| | - Mikkel Bentzon-Tilia
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts, Plads Bldg. 221, DK-2800 Kgs. Lyngby, Denmark
| | - Lone Gram
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts, Plads Bldg. 221, DK-2800 Kgs. Lyngby, Denmark
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12
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Roseobacter group probiotics exhibit differential killing of fish pathogenic Tenacibaculum species. Appl Environ Microbiol 2022; 88:e0241821. [PMID: 35080904 DOI: 10.1128/aem.02418-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fish pathogenic bacteria of the Tenacibaculum genus are a serious emerging concern in modern aquaculture, causing tenacibaculosis in a broad selection of cultured finfish. Data describing their virulence mechanisms are scarce and few means, antibiotic treatment aside, are available to control their proliferation in aquaculture systems. We genome sequenced a collection of 19 putative Tenacibaculum isolates from outbreaks at two aquaculture facilities and tested their susceptibility to treatment with tropodithietic acid (TDA)-producing Roseobacter group probiotics. We found that local outbreaks of Tenacibaculum can involve heterogeneous assemblages of species and strains with the capacity to produce multiple different virulence factors related to host invasion and infection. The probiotic Phaeobacter piscinae S26 proved efficient in killing pathogenic Tenacibaculum species such as T. maritimum, T. soleae, and some T. discolor strains. However, the T. mesophilum and T. gallaicum species exhibit natural tolerance towards TDA and are hence not likely to be easily killed by TDA-producing probiotics. Tolerance towards TDA in Tenacibaculum is likely involving multiple inherent physiological features pertaining to electron and proton transport, iron sequestration, and potentially also drug efflux mechanisms, as genetic determinants encoding such features were significantly associated with TDA tolerance. Collectively, our results support the use of TDA-producers to prevent tenacibaculosis, however, their efficacy is likely limited to some Tenacibaculum species. Importance A productive and sustainable aquaculture sector is needed to meet the UN sustainable development goals (SDGs) and supply the growing world population with high-protein food sources. A sustainable way to prevent disease outbreaks in the industry is the application of probiotic bacteria that can antagonize fish pathogens in the aquaculture systems. TDA-producing Roseobacter group probiotics have proven efficient in killing important vibrio pathogens and protecting fish larvae against infection, yet their efficacy against different fish pathogenic species of the Tenacibaculum genus has not been explored. Therefore, we tested the efficacy of such potential probiotics against a collection of different Tenacibaculum isolates and found the probiotic to efficiently kill a subset of relevant strains and species, supporting their use as sustainable disease control measure in aquaculture.
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13
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Three Novel Bacteria Associated with Two Centric Diatom Species from the Mediterranean Sea, Thalassiosira rotula and Skeletonema marinoi. Int J Mol Sci 2021; 22:ijms222413199. [PMID: 34947994 PMCID: PMC8706122 DOI: 10.3390/ijms222413199] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/03/2021] [Accepted: 12/04/2021] [Indexed: 11/23/2022] Open
Abstract
Diatoms are a successful group of microalgae at the base of the marine food web. For hundreds of millions of years, they have shared common habitats with bacteria, which favored the onset of interactions at different levels, potentially driving the synthesis of biologically active molecules. To unveil their presence, we sequenced the genomes of bacteria associated with the centric diatom Thalassiosira rotula from the Gulf of Naples. Annotation of the metagenome and its analysis allowed the reconstruction of three bacterial genomes that belong to currently undescribed species. Their investigation showed the existence of novel gene clusters coding for new polyketide molecules, antibiotics, antibiotic-resistance genes and an ectoine production pathway. Real-time PCR was used to investigate the association of these bacteria with three different diatom clones and revealed their preference for T. rotula FE80 and Skeletonema marinoi FE7, but not S. marinoi FE60 from the North Adriatic Sea. Additionally, we demonstrate that although all three bacteria could be detected in the culture supernatant (free-living), their number is up to 45 times higher in the cell associated fraction, suggesting a close association between these bacteria and their host. We demonstrate that axenic cultures of T. rotula are unable to grow in medium with low salinity (<28 ppt NaCl) whereas xenic cultures can tolerate up to 40 ppt NaCl with concomitant ectoine production, likely by the associated bacteria.
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14
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Characterization of oral and cloacal microbial communities in cold-stunned Kemp's ridley sea turtles (Lepidochelys kempii) during the time course of rehabilitation. PLoS One 2021; 16:e0252086. [PMID: 34043685 PMCID: PMC8159006 DOI: 10.1371/journal.pone.0252086] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 05/07/2021] [Indexed: 02/07/2023] Open
Abstract
Microbial communities of animals play a role in health and disease, including immunocompromised conditions. In the northeastern United States, cold-stunning events often cause endangered Kemp's ridley turtles (Lepidochelys kempii) to become stranded on beaches in autumn. These sea turtles are admitted to rehabilitation facilities when rescued alive and are presumed immunocompromised secondary to hypothermia. To better understand the role that microbes play in the health of cold-stunned sea turtles, we characterized the oral and cloacal microbiome from Kemp's ridley turtles at multiple timepoints during rehabilitation, from admission to pre-release, by using Illumina sequencing to analyze the 16S rRNA gene. Microbial communities were distinct between body sites and among turtles that survived and those that died. We found that clinical parameters such as presence of pneumonia or values for various blood analytes did not correlate with oral or cloacal microbial community composition. We also investigated the effect of antibiotics on the microbiome during rehabilitation and prior to release and found that the type of antibiotic altered the microbial community composition, yet overall taxonomic diversity remained the same. The microbiome of cold-stunned Kemp's ridley turtles gradually changed through the course of rehabilitation with environment, antibiotics, and disease status all playing a role in those changes and ultimately the release status of the turtles.
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15
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The Roseobacter-Group Bacterium Phaeobacter as a Safe Probiotic Solution for Aquaculture. Appl Environ Microbiol 2021; 87:e0258120. [PMID: 33310713 DOI: 10.1128/aem.02581-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phaeobacter inhibens has been assessed as a probiotic bacterium for application in aquaculture. Studies addressing the efficacy and safety indicate that P. inhibens maintains its antagonistic activity against pathogenic vibrios in aquaculture live cultures (live feed and fish egg/larvae) while having no or a positive effect on the host organisms and a minor impact on the host microbiomes. While P. inhibens produces antibacterial and algicidal compounds, no study has so far found a virulent phenotype of P. inhibens cells against higher organisms. Additionally, an in silico search for antibiotic resistance genes using published genomes of representative strains did not raise concerns regarding the risk for antimicrobial resistance. P. inhibens occurs naturally in aquaculture systems, supporting its safe usage in this environment. In conclusion, at the current state of knowledge, P. inhibens is a "safe-to-use" organism.
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16
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Buijs Y, Isbrandt T, Zhang SD, Larsen TO, Gram L. The Antibiotic Andrimid Produced by Vibrio coralliilyticus Increases Expression of Biosynthetic Gene Clusters and Antibiotic Production in Photobacterium galatheae. Front Microbiol 2020; 11:622055. [PMID: 33424823 PMCID: PMC7793655 DOI: 10.3389/fmicb.2020.622055] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 11/30/2020] [Indexed: 01/12/2023] Open
Abstract
The development and spread of multidrug resistant pathogens have reinforced the urgency to find novel natural products with antibiotic activity. In bacteria, orphan biosynthetic gene clusters (BGCs) far outnumber the BGCs for which chemistry is known, possibly because they are transcriptionally silent under laboratory conditions. A strategy to trigger the production of this biosynthetic potential is to challenge the microorganism with low concentrations of antibiotics, and by using a Burkholderia genetic reporter strain (Seyedsayamdost, Proc Natl Acad Sci 111:7266-7271), we found BGC unsilencing activity for the antimicrobial andrimid, produced by the marine bacterium Vibrio coralliilyticus. Next, we challenged another marine Vibrionaceae, Photobacterium galatheae, carrier of seven orphan BGCs with sub-inhibitory concentrations of andrimid. A combined approach of transcriptional and chemical measurements of andrimid-treated P. galatheae cultures revealed a 10-fold upregulation of an orphan BGC and, amongst others, a 1.6-2.2-fold upregulation of the gene encoding the core enzyme for biosynthesis of holomycin. Also, addition of andrimid caused an increase, based on UV-Vis peak area, of 4-fold in production of the antibiotic holomycin. Transcriptional measurements of stress response related genes in P. galatheae showed a co-occurrence of increased transcript levels of rpoS (general stress response) and andrimid induced holomycin overproduction, while in trimethoprim treated cultures attenuation of holomycin production coincided with a transcriptional increase of recA (SOS stress response). This study shows that using antimicrobial compounds as activators of secondary metabolism can be a useful strategy in eliciting biosynthetic gene clusters and facilitate natural product discovery. Potentially, such interactions could also have ecological relevant implications.
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Affiliation(s)
| | | | | | | | - Lone Gram
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
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17
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Kiesewalter HT, Lozano-Andrade CN, Strube ML, Kovács ÁT. Secondary metabolites of Bacillus subtilis impact the assembly of soil-derived semisynthetic bacterial communities. Beilstein J Org Chem 2020; 16:2983-2998. [PMID: 33335606 PMCID: PMC7722629 DOI: 10.3762/bjoc.16.248] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/18/2020] [Indexed: 12/26/2022] Open
Abstract
Secondary metabolites provide Bacillus subtilis with increased competitiveness towards other microorganisms. In particular, nonribosomal peptides (NRPs) have an enormous antimicrobial potential by causing cell lysis, perforation of fungal membranes, enzyme inhibition, or disruption of bacterial protein synthesis. This knowledge was primarily acquired in vitro when B. subtilis was competing with other microbial monocultures. However, our understanding of the true ecological role of these small molecules is limited. In this study, we have established soil-derived semisynthetic mock communities containing 13 main genera and supplemented them with B. subtilis P5_B1 WT, the NRP-deficient strain sfp, or single-NRP mutants incapable of producing surfactin, plipastatin, or bacillaene. Through 16S amplicon sequencing, it was revealed that the invasion of NRP-producing B. subtilis strains had no major impact on the bacterial communities. Still, the abundance of the two genera Lysinibacillus and Viridibacillus was reduced. Interestingly, this effect was diminished in communities supplemented with the NRP-deficient strain. Growth profiling of Lysinibacillus fusiformis M5 exposed to either spent media of the B. subtilis strains or pure surfactin indicated the sensitivity of this strain towards the biosurfactant surfactin. Our study provides a more in-depth insight into the influence of B. subtilis NRPs on semisynthetic bacterial communities and helps to understand their ecological role.
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Affiliation(s)
- Heiko T Kiesewalter
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Carlos N Lozano-Andrade
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Mikael L Strube
- Bacterial Ecophysiology and Biotechnology Group, DTU Bioengineering, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Ákos T Kovács
- Bacterial Interactions and Evolution Group, DTU Bioengineering, Technical University of Denmark, Kgs. Lyngby, Denmark
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18
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Duan Y, Petzold M, Saleem‐Batcha R, Teufel R. Bacterial Tropone Natural Products and Derivatives: Overview of their Biosynthesis, Bioactivities, Ecological Role and Biotechnological Potential. Chembiochem 2020; 21:2384-2407. [PMID: 32239689 PMCID: PMC7497051 DOI: 10.1002/cbic.201900786] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 04/02/2020] [Indexed: 12/05/2022]
Abstract
Tropone natural products are non-benzene aromatic compounds of significant ecological and pharmaceutical interest. Herein, we highlight current knowledge on bacterial tropones and their derivatives such as tropolones, tropodithietic acid, and roseobacticides. Their unusual biosynthesis depends on a universal CoA-bound precursor featuring a seven-membered carbon ring as backbone, which is generated by a side reaction of the phenylacetic acid catabolic pathway. Enzymes encoded by separate gene clusters then further modify this key intermediate by oxidation, CoA-release, or incorporation of sulfur among other reactions. Tropones play important roles in the terrestrial and marine environment where they act as antibiotics, algaecides, or quorum sensing signals, while their bacterial producers are often involved in symbiotic interactions with plants and marine invertebrates (e. g., algae, corals, sponges, or mollusks). Because of their potent bioactivities and of slowly developing bacterial resistance, tropones and their derivatives hold great promise for biomedical or biotechnological applications, for instance as antibiotics in (shell)fish aquaculture.
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Affiliation(s)
- Ying Duan
- Faculty of BiologyUniversity of Freiburg79104FreiburgGermany
| | - Melanie Petzold
- Faculty of BiologyUniversity of Freiburg79104FreiburgGermany
| | | | - Robin Teufel
- Faculty of BiologyUniversity of Freiburg79104FreiburgGermany
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19
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Changes in the Microbiome of Mariculture Feed Organisms after Treatment with a Potentially Probiotic Strain of Phaeobacter inhibens. Appl Environ Microbiol 2020; 86:AEM.00499-20. [PMID: 32385083 DOI: 10.1128/aem.00499-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 05/03/2020] [Indexed: 01/04/2023] Open
Abstract
The Phaeobacter genus has been explored as probiotics in mariculture as a sustainable strategy for the prevention of bacterial infections. Its antagonistic effect against common fish pathogens is predominantly due to the production of the antibacterial compound tropodithietic acid (TDA), and TDA-producing strains have repeatedly been isolated from mariculture environments. Despite many in vitro trials targeting pathogens, little is known about its impact on host-associated microbiomes in mariculture. Hence, the purpose of this study was to investigate how the addition of a TDA-producing Phaeobacter inhibens strain affects the microbiomes of live feed organisms and fish larvae. We used 16S rRNA gene sequencing to characterize the bacterial diversity associated with live feed microalgae (Tetraselmis suecica), live feed copepod nauplii (Acartia tonsa), and turbot (Scophthalmus maximus) eggs/larvae. The microbial communities were unique to the three organisms investigated, and the addition of the probiotic bacterium had various effects on the diversity and richness of the microbiomes. The structure of the live feed microbiomes was significantly changed, while no effect was seen on the community structure associated with turbot larvae. The changes were seen primarily in particular taxa. The Rhodobacterales order was indigenous to all three microbiomes and decreased in relative abundance when P. inhibens was introduced in the copepod and turbot microbiomes, while it was unaffected in the microalgal microbiome. Altogether, the study demonstrates that the addition of P. inhibens in higher concentrations, as part of a probiotic regime, does not appear to cause major imbalances in the microbiome, but the effects were specific to closely related taxa.IMPORTANCE This work is an essential part of the risk assessment of the application of roseobacters as probiotics in mariculture. It provides insights into the impact of TDA-producing Phaeobacter inhibens on the commensal bacteria related to mariculture live feed and fish larvae. Also, the study provides a sequencing-based characterization of the microbiomes related to mariculture-relevant microalga, copepods, and turbot larvae.
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20
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Stock W, Blommaert L, De Troch M, Mangelinckx S, Willems A, Vyverman W, Sabbe K. Host specificity in diatom-bacteria interactions alleviates antagonistic effects. FEMS Microbiol Ecol 2020; 95:5606784. [PMID: 31647551 DOI: 10.1093/femsec/fiz171] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 10/23/2019] [Indexed: 11/13/2022] Open
Abstract
While different microalgae tend to be associated with different bacteria, it remains unclear whether such specific associations are beneficial for the microalgae. We assessed the impact of bacterial isolates, derived from various marine benthic diatoms, on the growth of several strains belonging to the Cylindrotheca closterium diatom species complex. We first tested the effect of 35 different bacterial isolates on the growth of a single C. closterium strain, and then evaluated the impact of 8 of these isolates on the growth of 6 C. closterium strains and 1 Cylindrotheca fusiformis strain. Surprisingly, most interactions were neutral to antagonistic. The interactions were highly specific, with diatom growth in the presence of specific bacteria differing between Cylindrotheca strains and species, and closely related bacteria eliciting contrasting diatom growth responses. These differences could be related to the origin of the bacterial isolates, as only isolates from foreign diatom hosts significantly reduced diatom growth, implying coadaptation between different Cylindrotheca strains and their associated bacteria. Interestingly, the antagonistic effect of a Marinobacter strain was alleviated by the presence of a microbial inoculum that was native to the diatom host, suggesting that coadapted bacteria might also benefit their host indirectly by preventing the establishment of harmful bacteria.
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Affiliation(s)
- Willem Stock
- Laboratory of Protistology and Aquatic Ecology, Biology Department, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium
| | - Lander Blommaert
- Laboratory of Protistology and Aquatic Ecology, Biology Department, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium
| | - Marleen De Troch
- Marine Biology, Biology Department, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium
| | - Sven Mangelinckx
- SynBioC, Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Anne Willems
- Laboratory of Microbiology, Biology Department, Ghent University, Ledeganckstraat 35, 9000 Ghent, Belgium
| | - Wim Vyverman
- Laboratory of Protistology and Aquatic Ecology, Biology Department, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium
| | - Koen Sabbe
- Laboratory of Protistology and Aquatic Ecology, Biology Department, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium
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21
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Dittmann KK, Porsby CH, Goncalves P, Mateiu RV, Sonnenschein EC, Bentzon-Tilia M, Egan S, Gram L. Tropodithietic acid induces oxidative stress response, cell envelope biogenesis and iron uptake in Vibrio vulnificus. ENVIRONMENTAL MICROBIOLOGY REPORTS 2019; 11:581-588. [PMID: 31102321 DOI: 10.1111/1758-2229.12771] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/14/2019] [Accepted: 05/15/2019] [Indexed: 06/09/2023]
Abstract
The Roseobacter group is a widespread marine bacterial group, of which some species produce the broad-spectrum antibiotic tropodithietic acid (TDA). A mode of action for TDA has previously been proposed in Escherichia coli, but little is known about its effect on non-producing marine bacteria at in situ concentrations. The purpose of this study was to investigate how a sub-lethal level of TDA affects Vibrio vulnificus at different time points (30 and 60 min) using a transcriptomic approach. Exposure to TDA for as little as 30 min resulted in the differential expression of genes associated with cell regeneration, including the up-regulation of those involved in biogenesis of the cell envelope. Defence mechanisms including oxidative stress defence proteins and iron uptake systems were also up-regulated in response to TDA, while motility-related genes were down-regulated. Gene expression data and scanning electron microscopy imaging revealed a switch to a biofilm phenotype in the presence of TDA. Our study shows that a low concentration of this antibiotic triggers a defence response to reactive oxygen species and iron depletion in V. vulnificus, which indicates that the mode of action of TDA is likely more complex in this bacterium than what is known for E. coli.
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Affiliation(s)
- Karen K Dittmann
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
- School of Biological, Earth and Environmental Sciences, The University of New South Wales, Randwick, NSW, 2052, Australia
| | - Cisse H Porsby
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
| | - Priscila Goncalves
- School of Biological, Earth and Environmental Sciences, The University of New South Wales, Randwick, NSW, 2052, Australia
| | - Ramona Valentina Mateiu
- Center for Electron Nanoscopy, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
| | - Eva C Sonnenschein
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
| | - Mikkel Bentzon-Tilia
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
| | - Suhelen Egan
- School of Biological, Earth and Environmental Sciences, The University of New South Wales, Randwick, NSW, 2052, Australia
| | - Lone Gram
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, DK-2800, Denmark
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22
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Whalen KE, Becker JW, Schrecengost AM, Gao Y, Giannetti N, Harvey EL. Bacterial alkylquinolone signaling contributes to structuring microbial communities in the ocean. MICROBIOME 2019; 7:93. [PMID: 31208456 PMCID: PMC6580654 DOI: 10.1186/s40168-019-0711-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 06/05/2019] [Indexed: 05/27/2023]
Abstract
BACKGROUND Marine bacteria form complex relationships with eukaryotic hosts, from obligate symbioses to pathogenic interactions. These interactions can be tightly regulated by bioactive molecules, creating a complex system of chemical interactions through which these species chemically communicate thereby directly altering the host's physiology and community composition. Quorum sensing (QS) signals were first described in a marine bacterium four decades ago, and since then, we have come to discover that QS mediates processes within the marine carbon cycle, affects the health of coral reef ecosystems, and shapes microbial diversity and bacteria-eukaryotic host relationships. Yet, only recently have alkylquinolone signals been recognized for their role in cell-to-cell communication and the orchestration of virulence in biomedically relevant pathogens. The alkylquinolone, 2-heptyl-4-quinolone (HHQ), was recently found to arrest cell growth without inducing cell mortality in selected phytoplankton species at nanomolar concentrations, suggesting QS molecules like HHQ can influence algal physiology, playing pivotal roles in structuring larger ecological frameworks. RESULTS To understand how natural communities of phytoplankton and bacteria respond to HHQ, field-based incubation experiments with ecologically relevant concentrations of HHQ were conducted over the course of a stimulated phytoplankton bloom. Bulk flow cytometry measurements indicated that, in general, exposure to HHQ caused nanoplankton and prokaryotic cell abundances to decrease. Amplicon sequencing revealed HHQ exposure altered the composition of particle-associated and free-living microbiota, favoring the relative expansion of both gamma- and alpha-proteobacteria, and a concurrent decrease in Bacteroidetes. Specifically, Pseudoalteromonas spp., known to produce HHQ, increased in relative abundance following HHQ exposure. A search of representative bacterial genomes from genera that increased in relative abundance when exposed to HHQ revealed that they all have the genetic potential to bind HHQ. CONCLUSIONS This work demonstrates HHQ has the capacity to influence microbial community organization, suggesting alkylquinolones have functions beyond bacterial communication and are pivotal in driving microbial community structure and phytoplankton growth. Knowledge of how bacterial signals alter marine communities will serve to deepen our understanding of the impact these chemical interactions have on a global scale.
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Affiliation(s)
| | - Jamie W Becker
- Department of Biology, Haverford College, Haverford, PA, USA.
| | | | - Yongjie Gao
- Department of Biology, Haverford College, Haverford, PA, USA
| | | | - Elizabeth L Harvey
- Skidaway Institute of Oceanography, University of Georgia, Savannah, GA, USA
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23
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Stevick RJ, Sohn S, Modak TH, Nelson DR, Rowley DC, Tammi K, Smolowitz R, Markey Lundgren K, Post AF, Gómez-Chiarri M. Bacterial Community Dynamics in an Oyster Hatchery in Response to Probiotic Treatment. Front Microbiol 2019; 10:1060. [PMID: 31156583 PMCID: PMC6530434 DOI: 10.3389/fmicb.2019.01060] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 04/26/2019] [Indexed: 01/10/2023] Open
Abstract
Larval oysters in hatcheries are susceptible to diseases caused by bacterial pathogens, including Vibrio spp. Previous studies have shown that daily addition of the probiotic Bacillus pumilus RI06-95 to water in rearing tanks increases larval survival when challenged with the pathogen Vibrio coralliilyticus. We propose that the presence of probiotics causes shifts in bacterial community structure in rearing tanks, leading to a net decrease in the relative abundance of potential pathogens. During three trials spanning the 2012-2015 hatchery seasons, larvae, tank biofilm, and rearing water samples were collected from control and probiotic-treated tanks in an oyster hatchery over a 12-day period after spawning. Samples were analyzed by 16S rRNA sequencing of the V4 or V6 regions followed by taxonomic classification, in order to determine bacterial community structures. There were significant differences in bacterial composition over time and between sample types, but no major effect of probiotics on the structure and diversity of bacterial communities (phylum level, Bray-Curtis k = 2, 95% confidence). Probiotic treatment, however, led to a higher relative percent abundance of Oceanospirillales and Bacillus spp. in water and oyster larvae. In the water, an increase in Vibrio spp. diversity in the absence of a net increase in relative read abundance suggests a likely decrease in the abundance of specific pathogenic Vibrio spp., and therefore lower chances of a disease outbreak. Co-occurrence network analysis also suggests that probiotic treatment had a systemic effect on targeted members of the bacterial community, leading to a net decrease in potentially pathogenic species.
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Affiliation(s)
- Rebecca J. Stevick
- Graduate School of Oceanography, The University of Rhode Island, Narragansett, RI, United States
| | - Saebom Sohn
- Department of Fisheries, Animal and Veterinary Sciences, The University of Rhode Island, Kingston, RI, United States
| | - Tejashree H. Modak
- Department of Cell and Molecular Biology, The University of Rhode Island, Kingston, RI, United States
| | - David R. Nelson
- Department of Cell and Molecular Biology, The University of Rhode Island, Kingston, RI, United States
| | - David C. Rowley
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, The University of Rhode Island, Kingston, RI, United States
| | - Karin Tammi
- Feinstein School of Social and Natural Sciences, Roger Williams University, Bristol, RI, United States
| | - Roxanna Smolowitz
- Feinstein School of Social and Natural Sciences, Roger Williams University, Bristol, RI, United States
| | - Kathryn Markey Lundgren
- Feinstein School of Social and Natural Sciences, Roger Williams University, Bristol, RI, United States
| | - Anton F. Post
- Graduate School of Oceanography, The University of Rhode Island, Narragansett, RI, United States
- Division of Research, Florida Atlantic University, Boca Raton, FL, United States
| | - Marta Gómez-Chiarri
- Department of Fisheries, Animal and Veterinary Sciences, The University of Rhode Island, Kingston, RI, United States
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