Fig. 3

Lactate utilization genes in identified species of known genome sequences with corresponding protein domains: FAD-dependent lactate dehydrogenase (GlcD domain) (purple), (Fe–S)-binding protein GlpC (turquoise), lactate permease (LldP domain) (dark blue), lactate permease (LarA domain) (orange), electron transfer flavoproteins EtfA/B (light/deep green), fused GlcD/GlpC protein (light blue), lactate utilization LutB and LutC proteins (brown), NAD-dependent lactate dehydrogenase Ldh_2 (violet), transcriptional regulator GntR (gray), and other genes (yellow). Groups of genes coding for proteins with the GlcD and EtfA/B exclusively in one operon (a), coding the GlcD and GlpC only in a fusion or as probable operon (b), or possessing the lut operon and genes encoding GlcD and GlpC (c) are shown. Peptococcus niger DSM 20475 is shown separately (d) as an example of a bacterium possessing genes coding for both GlcD and EtfA/B as well as lut operons, plus additional copies of genes encoding GlcD and GlpC