Process optimization and activity evaluation of phenyllactic acid production by fermentation with kumquat-derived Lactobacillus plantarum strain CJEL01

WANG Liqi; ZHOU Luoshan; WANG Jingyi; LI Ziyuan; JIANG Tiemin; TANG Rongjun; LI Haiyun

doi:10.13557/j.cnki.issn1002-2813.2025.17.016

Abstract：The experiment aimed to investigate the process optimization of phenyllactic acid(PLA)production by fermenting kumquat pulp with Lactobacillus plantarum strain CJEL01 isolated from kumquat,as well as the biological activities of the fermented product.With the PLA yield as the evaluation index,single-factor experiments were conducted to optimize the fermentation conditions of the CJEL01 strain,and the antioxidant and antibacterial activities of the fermentation product were determined.The results showed that when phenylalanine was used as the substrate,the optimal fermentation process for CJEL01 to ferment kumquat pulp was as follows:The concentrations of phenylalanine,kumquat pulp,and glucose were 10,100,and 20 g/L,respectively,the pH value was six,fermentation temperature was 30 ℃,inoculum volume was 4％,liquid loading volume was 150 mL/250 mL,and the fermentation time was 96 hours.Under these conditions,the PLA yield reached 0.53 g/L.After concentrating the fermentation broth by five times,the clearance rates of 2,2-diphenyl-1-kylhydrazine(DPPH)and 3-ethylbenzothiazolin-6-sulfonic acid(ABTS)free radicals were 88.12％and 92.28％,respectively.The minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)against Staphylococcus aureus and Escherichia coli were both 3.13％.When phenylpyruvate was used as the substrate,the optimal fermentation process was as follows:The concentrations of phenylpyruvate,kumquat pulp,and glucose were 5,150,and 20 g/L respectively,the pH value was six,fermentation temperature was 30 ℃,inoculum volume was 6％,liquid loading volume was 180 mL/250 mL,and the fermentation time was 120 hours.Under these conditions,the PLA yield reached 4.50 g/L.After concentrating the fermentation broth by five times,the clearance rates of DPPH and ABTS free radicals were 91.53％and 96.06％,respectively.The MIC and MBC against Staphylococcus aureus and Escherichia coli were both 1.56％.The study indicates that the CJEL01 strain can effectively utilize kumquat pulp to produce PLA,enhancing the antioxidant and antimicrobial activities of the product.