Laboratory evolution of Geobacter sulfurreducens for enhanced growth on lactate via a single-base-pair substitution in a transcriptional regulator

ISME J. 2012 May;6(5):975-83. doi: 10.1038/ismej.2011.166. Epub 2011 Nov 24.

Abstract

The addition of organic compounds to groundwater in order to promote bioremediation may represent a new selective pressure on subsurface microorganisms. The ability of Geobacter sulfurreducens, which serves as a model for the Geobacter species that are important in various types of anaerobic groundwater bioremediation, to adapt for rapid metabolism of lactate, a common bioremediation amendment, was evaluated. Serial transfer of five parallel cultures in a medium with lactate as the sole electron donor yielded five strains that could metabolize lactate faster than the wild-type strain. Genome sequencing revealed that all five strains had non-synonymous single-nucleotide polymorphisms in the same gene, GSU0514, a putative transcriptional regulator. Introducing the single-base-pair mutation from one of the five strains into the wild-type strain conferred rapid growth on lactate. This strain and the five adaptively evolved strains had four to eight-fold higher transcript abundance than wild-type cells for genes for the two subunits of succinyl-CoA synthase, an enzyme required for growth on lactate. DNA-binding assays demonstrated that the protein encoded by GSU0514 bound to the putative promoter of the succinyl-CoA synthase operon. The binding sequence was not apparent elsewhere in the genome. These results demonstrate that a single-base-pair mutation in a transcriptional regulator can have a significant impact on the capacity for substrate utilization and suggest that adaptive evolution should be considered as a potential response of microorganisms to environmental change(s) imposed during bioremediation.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adaptation, Biological / genetics*
  • Amino Acid Sequence
  • Base Pairing
  • Base Sequence
  • Biodegradation, Environmental
  • DNA, Bacterial / genetics
  • Evolution, Molecular*
  • Geobacter / genetics*
  • Geobacter / growth & development
  • Geobacter / metabolism
  • Groundwater / microbiology
  • Lactic Acid / metabolism*
  • Molecular Sequence Data
  • Mutation
  • Operon
  • Promoter Regions, Genetic
  • Sequence Analysis, DNA

Substances

  • DNA, Bacterial
  • Lactic Acid