title: Heme and menaquinone induced electron transport in lactic acid bacteria.
abstract: BACKGROUND
  For some lactic acid bacteria higher biomass production as a result of aerobic respiration has been reported upon supplementation with heme and menaquinone. In this report, we have studied a large number of species among lactic acid bacteria for the existence of this trait.
  
  
  RESULTS
  Heme- (and menaquinone) stimulated aerobic growth was observed for several species and genera of lactic acid bacteria. These include Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacilllus brevis, Lactobacillus paralimentarius, Streptococcus entericus and Lactococcus garviae. The increased biomass production without further acidification, which are respiration associated traits, are suitable for high-throughput screening as demonstrated by the screening of 8000 Lactococcus lactis insertion mutants. Respiration-negative insertion-mutants were found with noxA, bd-type cytochrome and menaquinol biosynthesis gene-disruptions. Phenotypic screening and in silico genome analysis suggest that respiration can be considered characteristic for certain species.
  
  
  CONCLUSIONS
  We propose that the cyd-genes were present in the common ancestor of lactic acid bacteria, and that multiple gene-loss events best explains the observed distribution of these genes among the species.
authors.affiliation: TI food & Nutrition, Kluyver Centre for Genomics of Industrial Fermentation, Po Box 557, 6700 AN, Wageningen, the Netherlands. jeroen.hugenholtz@nizo.nl.
authors.forename: Rob
authors.initials: R
authors.lastname: Brooijmans
authors.forename: Bart
authors.initials: B
authors.lastname: Smit
authors.forename: Filipe
authors.initials: F
authors.lastname: Santos
authors.forename: Jan
authors.initials: J
authors.lastname: van Riel
authors.forename: Willem M
authors.initials: WM
authors.lastname: de Vos
authors.forename: Jeroen
authors.initials: J
authors.lastname: Hugenholtz