초록
<P><B>Abstract</B></P> <P>The <I>Escherichia coli</I> BW25113 or MC4100 wild type parental strains growth and H<SUB>2</SUB> production kinetics was studied in batch cultures of minimal salt medium (MSM) and peptone medium (PM) at pH of 5.5–7.5 upon glycerol (10 g L<SUP>−1</SUP>) fermentation and formate (0.68 g L<SUP>−1</SUP>) supplementation. The role of formate alone or with glycerol on growth and H<SUB>2</SUB> production via hydrogenases (Hyd) was investigated in double <I>hyaB hybC</I> (lacking large subunits of Hyd 1 and 2), triple <I>hyaB hybC hycE</I> (lacking large subunits of Hyds 1-3) and sole <I>selC</I> (lacking formate dehydrogenase H) mutants during 24 h bacterial growth. H<SUB>2</SUB> production was delayed and observed after 24 h bacterial wild type strains growth on MSM. Moreover, it reached the maximal values after 72 h growth at the pH 6.5 and pH 7.5. Biomass formation of the mutants used was inhibited ∼3.5 fold compared with wild type, and H<SUB>2</SUB> production was absent in <I>hyaB hybC hycE</I> and <I>selC</I> mutants upon glycerol utilization on MSM at pHs of 5.5–7.5. Formate inhibited bacterial growth on MSM with glycerol, but enhanced and recovered H<SUB>2</SUB> production by <I>hybC</I> mutant at pH 7.5. H<SUB>2</SUB> evolution was delayed at pH 7.5 in PM, but observed and stimulated at pH 6.5 upon glycerol and formate utilization in <I>hyaB hybC</I> mutant. H<SUB>2</SUB> production was absent in <I>hyaB hybC hycE</I> and <I>selC</I> mutants upon glycerol, formate alone or with glycerol fermentation at pH 6.5 and pH 7.5; formate supplementation had no effect. The results point out <I>E. coli</I> ability to grow and utilize glycerol in MSM with comparably high H<SUB>2</SUB> yield: as well as they suggest the key role of Hyd-3 at both pH 6.5 and pH 7.5 and the role of Hyd-2 and Hyd-4 at pH 7.5 in H<SUB>2</SUB> production by <I>E. coli</I> during glycerol fermentation with formate supplementation. The results obtained are novel and might be useful in H<SUB>2</SUB> production biotechnology development using different nutrient media and glycerol and formate as feedstock.</P> <P><B>Highlights</B></P> <P> <UL> <LI> H<SUB>2</SUB> was produced by <I>E. coli</I> in minimal salt medium with glycerol after 24 h growth. </LI> <LI> Maximal values of H<SUB>2</SUB> were observed for 72 h growth, at pH 6.5 and 7.5. </LI> <LI> Formate changed H<SUB>2</SUB> production in mutants with defective hydrogenases (Hyd). </LI> <LI> H<SUB>2</SUB> evolution was delayed in peptone medium (PM) with glycerol at pH 7.5. </LI> <LI> H<SUB>2</SUB> production was changed in different mutants in PM; formate had no effect. </LI> </UL> </P>