芳香族氨基酸对沼泽红假单胞菌合成CoQ10的影响

CoQ10具有呼吸链电子传递者、抗氧化性、调控基因表达等多种生理生化功能.目前不仅用作药物也用作食品添加剂.微生物发酵法是当前生产CoQ10的主要方法.在细菌中,芳香族氨基酸和CoQ10的苯核环都是通过莽草酸途径合成;它们在生物体中各自的合成存在着相互调控作用.本试验通过在培养过程中添加芳香族氨基酸来考察了其对沼泽红假单胞菌J001合成CoQ10的影响.结果表明:当色氨酸添加量≥15 mg/L时对CoQ10的合成具有强列的抑制作用;苯丙氨酸添加量≥50mg/L时对CoQ10的合成具有一定的抑制作用但当添加量≥75mg/L后对CoQ10的合成变为一定的促进作用;酪氨酸添加量为75～175 mg/L时对CoQ10的合成具有一定的促进作用,但当添加量≥200 mg/L后对CoQ10的合成变为一定的抑制作用.当添加苯丙氨酸100 mg/L+酪氨酸150mg/L时,CoQ10含量达最高(25.6±1.3 mg CoQ10/g干细胞),比不添加对照提高52.2%.以上结果说明:该菌株CoQ10的合成受到3种芳香族氨基酸的调控,3-脱氧-D-阿拉伯己酮糖-7-磷酸合成酶是同工酶系统并主要受色氨酸调控,无色氨酸培养基及在培养期间添加适量的苯丙氨酸与酪氨酸对该菌株合成CoQl.有利.

Effects of aromatic amino acids on the biosynthesis of CoQ10 in Rhodopseudomonas palustris

CoQ10 has been used not only as a drug but also as a food supplement because of its various Dhysi ological and biochemical activities.Microbial fermentation is a main way for the commercial production of CoQ10.The quinoid nucleus of CoQ10 and aromatic amino acids are synthesized from the shikimate pathway in bacteria and there are some effects of them on another biosynthesis.The impacts of aromatic amino acids on the biosynthesis of CoQ10 in Rhodopseudomnas palustris J001 were investigated with feeding aromatic amino acids at the end of the logarithmic phase during incubation.The results showed that the feeding of tryptophan(above 15 mg/L) strongly repressed the biosynthesis of CoQ10.There were also some slightly unfavorable effects of feeding of phenylalanine(50 mg/L)and tyrosine(above 200 rag/L)on the biosynthesis of CoQl0.However,the biosynthe sis of CoQ10 could be enhanced by feeding phenylalanine(above 75 mg/L)Or tyrosine(from 75 to 1 75 mg/L).The content of CoQ10 in the strain was found to be the highest up tO(25.6±1.3)mg CoQ10/g dried biomass when feeding phenylalanine(1 00 mg/L)+tyrosine(1 50 mg/L),which was 52.2% higher than that in the control with no additional amino acids in the medium.The results indicated that the biosynthesis of CoqIo was affected by the three aromatic amino acids.It can be concluded that the biosynthesis of CoQ10 in strain is favorable by feeding appropriate amount of phenylalanien and tyrosine without tryptophan.