氨氮对淀粉酶产色链霉菌产ε-聚赖氨酸的影响

Effect of ammonia nitrogen on the production of ε-poly-L-lysinein Streptomyces diastatochromogenes

ε-聚赖氨酸(ε-poly-L-lysine,ε-PL)是一种新型广谱天然防腐剂。由于生产成本较高,价格昂贵,限制了其在食品工业上的广泛应用。为降低生产成本,研究了不同氨氮(NH4^+-N)浓度对淀粉酶产色链霉菌生产ε-聚赖氨酸的影响。摇瓶发酵试验结果表明,当NH+4-N初始质量浓度为0.5g/L时,提高了天冬氨酸激酶(aspartokinase,Ask)和聚赖氨酸合成酶(polylysine synthetase,Pls)的活力,发酵96h,ε-PL产量达到0.95g/L,与对照组相比提高了15.13%。5L发酵罐分批发酵和流加发酵实验确定了一种有效提高ε-PL产量的方法:初始NH4^+-N质量浓度2.5g/L,发酵过程中流加(NH4)2SO4使NH4^+-N质量浓度维持在0.5g/L。采用此工艺进行补料分批发酵,ε-PL最高产量达到27.67g/L,与对照组相比提高了17.72%。

ε-poly- L -lysine(ε-PL) is a new type of broad-spectrum natural food preservative. Because of its high cost and high price, its application in food industry is limited. In order to reduce the production cost, the effect of ammonia nitrogen (NH4^+-N) concentration on the production of ε-PL by Streptomyces diastatochromogenes was studied. Results indicated that the yield of ε-PL was 0.95 g/L,improved by 15.13% compared with the control group and the activities of Ask and Pls were improved when the initial concentration of NH4^+-N was 0.5 g/L fermented in shaking flasks for 96 h. An effective increasing ε-PL production method was verified by the batch and fed-batch fermentations: The initial concentration of NH4^+-N was 2.5 g/L, ammonium sulfate maintains the concentration of 0.5 g/L in 5 L the fermenter by fed-batch. In this method, the final yield of ε-PL was 27.67 g/L, which was improved by 17.72% contrasting to the control group.