Effects of Phenylalanine and Phenylpyruvic Acid on Biosynthesis of Phenyllactic Acid with Lactobacillus sp.SK007

One strain,Lactobacillus sp.SK007,which was isolated from Chinese traditional pickles,could produce the highest phenyllactic acid(PLA) yield(0.55 mmol/L) in the Man-Rogosa-Sharpe(MRS) medium.The PLA production from phenylalanine(Phe) by Lactobacillus sp.SK007 was investigated.It was found that Phe remained 94%,but the intermediate metabolite phenylpyruvic acid(PPA) stayed below the detection level.These results indicated that the transamination of Phe to PPA is a rate-limiting step.The bottleneck was overcome using PPA to replace Phe as substrate.Furthermore,the fermentation conditions of PLA production from PPA by Lactobacillus sp.SK007 were optimized.Under the optimal conditions of 18.3 mmol/L PPA,and 24 h cultivation at 30℃ without shaking,PLA concentration reached 10.25 mmol/L.