title: Characterization of three lactic acid bacteria and their isogenic ldh deletion mutants shows optimization for YATP (cell mass produced per mole of ATP) at their physiological pHs.
abstract: Several lactic acid bacteria use homolactic acid fermentation for generation of ATP. Here we studied the role of the lactate dehydrogenase enzyme on the general physiology of the three homolactic acid bacteria Lactococcus lactis, Enterococcus faecalis, and Streptococcus pyogenes. Of note, deletion of the ldh genes hardly affected the growth rate in chemically defined medium under microaerophilic conditions. However, the growth rate was affected in rich medium. Furthermore, deletion of ldh affected the ability for utilization of various substrates as a carbon source. A switch to mixed acid fermentation was observed during glucose-limited continuous growth and was dependent on the growth rate for S. pyogenes and on the pH for E. faecalis. In S. pyogenes and L. lactis, a change in pH resulted in a clear change in Y(ATP) (cell mass produced per mole of ATP). The pH that showed the highest Y(ATP) corresponded to the pH of the natural habitat of the organisms.
authors.affiliation: University of Rostock, Institute of Medical Microbiology, Virology, and Hygiene, Schillingallee 70, 18057 Rostock, Germany. tomas.fiedler@med.uni-rostock.de
authors.forename: Tomas
authors.initials: T
authors.lastname: Fiedler
authors.forename: Martijn
authors.initials: M
authors.lastname: Bekker
authors.forename: Maria
authors.initials: M
authors.lastname: Jonsson
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Mehmeti
authors.forename: Anja
authors.initials: A
authors.lastname: Pritzschke
authors.forename: Nikolai
authors.initials: N
authors.lastname: Siemens
authors.forename: Ingolf
authors.initials: I
authors.lastname: Nes
authors.forename: Jeroen
authors.initials: J
authors.lastname: Hugenholtz
authors.forename: Bernd
authors.initials: B
authors.lastname: Kreikemeyer
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D018533:Biomass; D002244:Carbon / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D013293:Enterococcus faecalis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007770:L-Lactate Dehydrogenase / Q000172:deficiency*; D019344:Lactic Acid / Q000378:metabolism*; D013294:Lactococcus lactis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D017384:Sequence Deletion; D013297:Streptococcus pyogenes / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D003470:Culture Media; D019344:Lactic Acid; D002244:Carbon; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase