學生姓名:
呂思璇
指導教授:
潘崇良
學期:
106上
摘 要:
Phenyllactic acid (PLA), a phenolic acid phytochemical with the antimicrobial activity, was rarely reported in food. This study evidenced a new food source of PLA and elucidated its metabolic mechanism. PLA naturally occurred in Chinese pickles in 23 pickle samples. Then, lactic acid bacteria capable of metabolizing PLA were screened and a promising strain was characterized as Lactobacillus plantarum. Moreover, the investigation of the metabolic mechanism of PLA in pickles suggested that the yield of PLA was positively related to the content of phenylalanine in food. This study also elucidate the antibacterial mechanism of PLA against Listeria monocytogenes and Escherichia coli. Flow cytometry analysis stained with propidium iodide (PI) demonstrated that PLA could damage the membrane integrity of List. monocytogenes, while it could not disrupt that of E. coli. The uptake of 1-N-phenylnaphthylamine (NPN) indicated that PLA interrupted the outer membrane permeability of E. coli. Scanning electron microscopy (SEM) observation visualized the damage caused by PLA as morphological changes in List. monocytogenes and E. coli. Fluorescence assays demonstrated that PLA could interact with bacterial genomic DNA in the manner of intercalation. These findings suggested dual antibacterial targets of PLA, namely membrane and genomic DNA, are observed.
摘要.pdf