Regulatory effect of the typical methyl-group donors on the oxygen metabolism in Pseudomonas denitrificans

In this paper, the fermentation processes of Pseudomonas denitrificans were investigated in 7L fermenter by using betaine and choline chloride as the typical methyl-group donors for vitamin B₁₂ biosynthesis, respectively.When using choline chloride as the methyl-group donor, the dissolved oxygen (DO) and pH respectively presented an obviously zooming and dropping phenomena, resulting in a slow cell growth and low vitamin B₁₂biosynthesis.However, the metabolism capability under betaine as methyl-group donor was significantly better than that of choline chloride, and the pH and DO could be maintained at a stable and appropriate level during the whole fermentation processes.As a result, the final cell growth and vitamin B₁₂ production were significantly higher than those obtained in choline chloride.