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Hillesland KL, Lim S, Flowers JJ, Turkarslan S, Pinel N, Zane GM, Elliott N, Qin Y, Wu L, Baliga NS, Zhou J, Wall JD, Stahl DA. Erosion of functional independence early in the evolution of a microbial mutualism. Proc Natl Acad Sci U S A 2014; 111:14822-7. [PMID: 25267659 PMCID: PMC4205623 DOI: 10.1073/pnas.1407986111] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Many species have evolved to function as specialized mutualists, often to the detriment of their ability to survive independently. However, there are few, if any, well-controlled observations of the evolutionary processes underlying the genesis of new mutualisms. Here, we show that within the first 1,000 generations of initiating independent syntrophic interactions between a sulfate reducer (Desulfovibrio vulgaris) and a hydrogenotrophic methanogen (Methanococcus maripaludis), D. vulgaris frequently lost the capacity to grow by sulfate respiration, thus losing the primary physiological attribute of the genus. The loss of sulfate respiration was a consequence of mutations in one or more of three key genes in the pathway for sulfate respiration, required for sulfate activation (sat) and sulfate reduction to sulfite (apsA or apsB). Because loss-of-function mutations arose rapidly and independently in replicated experiments, and because these mutations were correlated with enhanced growth rate and productivity, gene loss could be attributed to natural selection, even though these mutations should significantly restrict the independence of the evolved D. vulgaris. Together, these data present an empirical demonstration that specialization for a mutualistic interaction can evolve by natural selection shortly after its origin. They also demonstrate that a sulfate-reducing bacterium can readily evolve to become a specialized syntroph, a situation that may have often occurred in nature.
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Affiliation(s)
| | - Sujung Lim
- Biological Sciences, University of Washington Bothell, Bothell, WA 98011
| | | | | | - Nicolas Pinel
- Civil and Environmental Engineering, and Institute for Systems Biology, Seattle, WA 98109-5234
| | - Grant M Zane
- Department of Biochemistry, University of Missouri, Columbia, MO 65211
| | | | - Yujia Qin
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019
| | - Liyou Wu
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019
| | - Nitin S Baliga
- Institute for Systems Biology, Seattle, WA 98109-5234; Departments of Biology and Microbiology, Molecular and Cellular Biology Program, University of Washington Seattle, Seattle, WA 98195; Lawrence Berkeley National Laboratory, Berkeley, CA 94720; and
| | - Jizhong Zhou
- Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019; Earth Science Division, State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Judy D Wall
- Department of Biochemistry, University of Missouri, Columbia, MO 65211
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