Thus, the bacterial growth-stimulating effect of formate in
combination with glycerol fermentation was pH-dependent.
In contrast to pH 7.5, the bacterial growth-stimulating effect
was observed at pH 6.5 at the late stationary phase for wild
type and Hyd-1, Hyd-2 and Hyd-4; this effect was not determined
for the Hyd-3-inactivated mutant. These effects can be
compared with optimal glycerol fermentation at pH 6.3 [7,8].
Moreover, Hyd-3 was shown to be more active at acidic pH and
upon formate supplementation. Hyd-3 activity via FHL may be
required to supply CO2 necessary for bacterial growth