无机氮源对脱氮假单胞杆菌产维生素B_(12)代谢过程的影响

Effect of inorganic nitrogen sources on the metabolic process of vitamin B_(12) producing by Pseudomonas denitrificans

通过摇瓶培养的方式研究了无机氮源对脱氮假单胞杆菌发酵产维生素B12的代谢调控作用。首先考察了硫酸铵、硝酸铵、硝酸钠、磷酸氢二铵和氯化铵等5种不同无机氮源对脱氮假单胞杆菌代谢过程的影响。结果表明,硫酸铵是维生素B12发酵较为适宜的无机氮源;在此基础上进一步研究了NH4+浓度对脱氮假单胞杆菌发酵过程的影响,结果发现高浓度的NH4+能明显促进菌体的生长,但是会对维生素B12的合成产生一定的负作用;基于此,提出了脱氮假单胞杆菌摇瓶发酵过程的NH4+限制性补加策略,以克服NH4+在菌体生长与维生素B12合成上的矛盾。

The metabolic regulation of inorganic nitrogen sources involved in vitamin B12 shake-flask fermentation by Pseudomonas denitrificans was studied in this paper. Firstly,the effects of various inorganic nitrogen sources （（NH4）2SO4,NH4NO3,NaNO3,（NH4）2HPO4 and NH4Cl） on P. denitrificans metabolism were investigated,and the result showed that ammonium sulfate was more favorable for vitamin B12 fermentation. Based on this fact,the effects of NH4＋ concentrations on P. denitrificans fermentation processes were further researched,and it was discovered that the presence of high NH4＋ concentration could significantly accelerate the cell growth but had negative action on vitamin B12 biosynthesis. Therefore,in order to overcome the contradiction between cell growth and vitamin B12 biosynthesis,the strategy of NH4＋ restrictively feeding was implemented in shake-flask fermentation by P. denitrificans.