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Catlett JL, Carr S, Cashman M, Smith MD, Walter M, Sakkaff Z, Kelley C, Pierobon M, Cohen MB, Buan NR. Metabolic Synergy between Human Symbionts Bacteroides and Methanobrevibacter. Microbiol Spectr 2022; 10:e0106722. [PMID: 35536023 PMCID: PMC9241691 DOI: 10.1128/spectrum.01067-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 04/11/2022] [Indexed: 12/12/2022] Open
Abstract
Trophic interactions between microbes are postulated to determine whether a host microbiome is healthy or causes predisposition to disease. Two abundant taxa, the Gram-negative heterotrophic bacterium Bacteroides thetaiotaomicron and the methanogenic archaeon Methanobrevibacter smithii, are proposed to have a synergistic metabolic relationship. Both organisms play vital roles in human gut health; B. thetaiotaomicron assists the host by fermenting dietary polysaccharides, whereas M. smithii consumes end-stage fermentation products and is hypothesized to relieve feedback inhibition of upstream microbes such as B. thetaiotaomicron. To study their metabolic interactions, we defined and optimized a coculture system and used software testing techniques to analyze growth under a range of conditions representing the nutrient environment of the host. We verify that B. thetaiotaomicron fermentation products are sufficient for M. smithii growth and that accumulation of fermentation products alters secretion of metabolites by B. thetaiotaomicron to benefit M. smithii. Studies suggest that B. thetaiotaomicron metabolic efficiency is greater in the absence of fermentation products or in the presence of M. smithii. Under certain conditions, B. thetaiotaomicron and M. smithii form interspecies granules consistent with behavior observed for syntrophic partnerships between microbes in soil or sediment enrichments and anaerobic digesters. Furthermore, when vitamin B12, hematin, and hydrogen gas are abundant, coculture growth is greater than the sum of growth observed for monocultures, suggesting that both organisms benefit from a synergistic mutual metabolic relationship. IMPORTANCE The human gut functions through a complex system of interactions between the host human tissue and the microbes which inhabit it. These diverse interactions are difficult to model or examine under controlled laboratory conditions. We studied the interactions between two dominant human gut microbes, B. thetaiotaomicron and M. smithii, using a seven-component culturing approach that allows the systematic examination of the metabolic complexity of this binary microbial system. By combining high-throughput methods with machine learning techniques, we were able to investigate the interactions between two dominant genera of the gut microbiome in a wide variety of environmental conditions. Our approach can be broadly applied to studying microbial interactions and may be extended to evaluate and curate computational metabolic models. The software tools developed for this study are available as user-friendly tutorials in the Department of Energy KBase.
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Affiliation(s)
- Jennie L. Catlett
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Sean Carr
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Mikaela Cashman
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Megan D. Smith
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Mary Walter
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Zahmeeth Sakkaff
- Department of Computer Science & Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Christine Kelley
- Department of Mathematics, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Massimiliano Pierobon
- Department of Computer Science & Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Myra B. Cohen
- Department of Computer Science & Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
- Department of Computer Science, Iowa State University, Ames, Iowa, USA
| | - Nicole R. Buan
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
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White KA, McEntire KD, Buan NR, Robinson L, Barbar E. Charting a New Frontier Integrating Mathematical Modeling in Complex Biological Systems from Molecules to Ecosystems. Integr Comp Biol 2021; 61:2255-2266. [PMID: 34283225 DOI: 10.1093/icb/icab165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 07/09/2021] [Accepted: 07/16/2021] [Indexed: 11/14/2022] Open
Affiliation(s)
| | | | - Nicole R Buan
- University of Nebraska-Lincoln, Department of Biochemistry
| | | | - Elisar Barbar
- Oregon State University, Department of Biochemistry and Biophysics
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