| During fermentation,the abundant amino acids in Chinese rice wine fermenting broth generate a lot of nutrients,as well as some undesirable compounds such as biogenic amines?BAs?that may compromise the health of consumers.Lactic acid bacteria?LAB?,which plays an important role in the brewing progress of Chinese rice wine,is the main bacterial capable of producing BAs through decarboxylation of certain amino acids.The ability for LAB to produce BA is strain dependent.In this study,LAB strains were isolated from Chinses rice wine fermentation process and cultured in decarboxylation medium to analyze BAs accumulation by reversed-phase high-performance liquid chromatography?RP-HPLC?.The biosynthesis pathways of BAs in Lctobacillus curvatus 1-4 strain which accumulated a large amount of putrescine were also analyzed.The results are as follows:?1?A total of 82 LAB strains involved in Chinses rice wine fermentation process were isolated and identified through 16 S r DNA analysis,including 63 strains of Lactobacillus,6 strains of Leuconostoc,2 strains of Lactococcus and 1 strains of Weissella.RP-HPLC were employed to analyze the BA accumulation capability of the strains.11 strains were detected to accumulate histamine with 20.26?299.94 mg·L-1,28 strains could produce tyramine with 9.20?30.38 mg·L-1,and 51 strains exhibited putrescine formation capability with 20.26?299.94 mg·L-1.The Lactobacillus curvatus 1-4 strain,which was isolated from the rice immersion water,accumulated a large amount of putrescine,and therefore was further studied.?2?L.curvatus 1-4 strain was cultured in decarboxylation medium supplemented with different precursors,including arginine and ornithine.It was found that L.curvatus 1-4 strain can utilize both arginine and ornithine and produce putrescine,through agmatine deiminase,ornithine decarboxylase?ODC?and arginine deiminase pathway?ADI?,with 100.46 mg·L-1,303.86 mg·L-1,166.42 mg·L-1 of putrescine accumulated,respectively.The genes that encoded enzymes in ODC and ADI pathway,including arc A?arc B?odc?pot E,were proved to be existed in the genome of the strain.Proteomic analysis showed peptidase and transporters were specifically expressed in the cel s of mature stage,in which the putrescine was largely formed and accumulated,suggested the more amino acid precursor were generated.?3?When cultured in decarboxylation medium supplemented with ornithine and 5'-PLP at different temperatures?4oC,15oC,30oC?,the L.curvatus 1-4 strain grew better,and accumulated highest amount of putrescine at 30oC.When 5%,10%,15% alcohol was presented in the medium,the accumulated putrescine were 241.15 mg·L-1,235.47 mg·L-1 and 233.57 mg·L-1 resepectively.When cultured in the decarboxylation medium with p H of 3.0,3.5,4.0,4.5,5.0,5.5),the L.curvatus 1-4 strain produced most putrescine at p H 4.0,either ornithine or arginine was supplemented as precursors.These results suggested that moderate temperature and acidic p H promote the formation of putrescine,alcohol concentration under 15% would not affect the putrescine accumulation. |
PDF Full Text Request