title: Characterization of NaCl tolerance in Desulfovibrio vulgaris Hildenborough through experimental evolution.
abstract: Desulfovibrio vulgaris Hildenborough strains with significantly increased tolerance to NaCl were obtained via experimental evolution. A NaCl-evolved strain, ES9-11, isolated from a population cultured for 1200 generations in medium amended with 100 mM NaCl, showed better tolerance to NaCl than a control strain, EC3-10, cultured for 1200 generations in parallel but without NaCl amendment in medium. To understand the NaCl adaptation mechanism in ES9-11, we analyzed the transcriptional, metabolite and phospholipid fatty acid (PLFA) profiles of strain ES9-11 with 0, 100- or 250 mM-added NaCl in medium compared with the ancestral strain and EC3-10 as controls. In all the culture conditions, increased expressions of genes involved in amino-acid synthesis and transport, energy production, cation efflux and decreased expression of flagellar assembly genes were detected in ES9-11. Consistently, increased abundances of organic solutes and decreased cell motility were observed in ES9-11. Glutamate appears to be the most important osmoprotectant in D. vulgaris under NaCl stress, whereas, other organic solutes such as glutamine, glycine and glycine betaine might contribute to NaCl tolerance under low NaCl concentration only. Unsaturation indices of PLFA significantly increased in ES9-11. Branched unsaturated PLFAs i17:1 ω9c, a17:1 ω9c and branched saturated i15:0 might have important roles in maintaining proper membrane fluidity under NaCl stress. Taken together, these data suggest that the accumulation of osmolytes, increased membrane fluidity, decreased cell motility and possibly an increased exclusion of Na(+) contribute to increased NaCl tolerance in NaCl-evolved D. vulgaris.
authors.affiliation: Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019, USA.
authors.forename: Aifen
authors.initials: A
authors.lastname: Zhou
authors.forename: Edward
authors.initials: E
authors.lastname: Baidoo
authors.forename: Zhili
authors.initials: Z
authors.lastname: He
authors.forename: Aindrila
authors.initials: A
authors.lastname: Mukhopadhyay
authors.forename: Jason K
authors.initials: JK
authors.lastname: Baumohl
authors.forename: Peter
authors.initials: P
authors.lastname: Benke
authors.forename: Marcin P
authors.initials: MP
authors.lastname: Joachimiak
authors.forename: Ming
authors.initials: M
authors.lastname: Xie
authors.forename: Rong
authors.initials: R
authors.lastname: Song
authors.forename: Adam P
authors.initials: AP
authors.lastname: Arkin
authors.forename: Terry C
authors.initials: TC
authors.lastname: Hazen
authors.forename: Jay D
authors.initials: JD
authors.lastname: Keasling
authors.forename: Judy D
authors.initials: JD
authors.lastname: Wall
authors.forename: David A
authors.initials: DA
authors.lastname: Stahl
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000222:Adaptation, Physiological; D005075:Biological Evolution; D016969:Desulfovibrio vulgaris / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D004734:Energy Metabolism / Q000235:genetics; D005227:Fatty Acids / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D008560:Membrane Fluidity / Q000235:genetics; D012965:Sodium Chloride / Q000378:metabolism*
chemical_list: D005227:Fatty Acids; D012965:Sodium Chloride