In order to alleviate oxygen limitation and improve the yield of poly-c-glutamic acid (c-PGA) during fermentation,
the Vitreoscilla hemoglobin gene (vgb) was integrated into the chromosome of Bacillus subtilis
and expressed during c-PGA production. The activity of the expressed Vitreoscilla hemoglobin (VHb) was
confirmed by CO-difference spectrum. Expression of VHb enhanced cell growth under high viscosity fermentation
conditions 1.26-fold and increased the yield of c-PGA 2.07-fold. These results indicate that the
expression of VHb could be advantageous in high viscosity fermentation media