硝酸盐、镁盐对林可霉素生物合成的促进作用

Stimulative Effects of Nitrate and Magnesium Salts on Biosynthesis of Lincomycin by Streptomyces lincolnensis

在林肯链霉菌生物合成林可霉素代谢调节的研究中，发现硝酸盐可明显促进林可霉素的生物合成．加入硝酸钾０．８％，林肯链霉菌合成林可霉素的产量可增加３７％．在发酵９６ｈ之前加入硝酸盐均能促进林可霉毒的合成，但产量的增加随加入时间的延迟而降低．硝酸钾在促进产量的同时，使菌体生长减少，看来硝酸盐对林可霉素的合成与菌体生长之间起着调节作用．洗涤菌体试验指出，硝酸盐的加入诱导了林可霉素合成所需要的酶系，这可能是加入硝酸盐后，产生进一步氮代谢的结果；蛋白胨不能代替硝酸盐，进一步说明硝酸钾的作用并不是作为氮源利用．在蛋白质合成抑制剂氯霉素存在下，硝酸盐不再能促进林可霉素的合成，说明氯霉素抑制了硝酸盐或其代谢中间物所诱导的酶系的合成．同时还报导了镁盐促进林可霉素生物合成现象的初步观察结果．硫酸镁在促进林可霉素产量提高的同时，使菌体生长延迟．硫酸镁的这种作用机制可能是通过磷酸镁铵沉淀，降低了培养基中游离氨和可溶性磷酸盐浓度，解除了铵盐和磷酸盐对林可霉素合成的抑制．

Streptomyces lincolnensis ,when grown in medium contataining nitrate,synthesies lincomycin 37% higher than that in the medium without nitrate.The stimulative effect of nitrate becomes less and less effective when nitrate is added from 24 to 96 hour in the course of fermentation.The data indicate that higher production of lincomycin is associated with less growth of mycelium.It seems that nitrate plays a regulatory role in the biosynthesis of lincomycin and the growth of mycelium.The results obtained from the washed mycelium experiments show that nitrate might induce an enzyme(s) leading to the synthesis of lincomycin,peptone can not be used instead of nitrate. It is obviousy that nitrate is not used as a nitrogen source,and may act as an inducer.It was also studied that lincomycin biosynthesis was increased when MgSO 4 was added into medium.The mechanism for this effect maybe due to the reduction of free ammonium and soluble phosphate in the medium through the precipitation of ammonium magnesium phosphate.