水果酵素自然发酵过程中优势菌群与有机酸变化规律分析

Analysis of the Relationship between Bacterial Community Composition and Changes in Organic Acids during Natural Fermentation of Mixed Fruits

分析3种自然发酵的水果酵素优势菌群与有机酸变化规律。高效液相色谱法测定有机酸含量变化,聚合酶链式反应-变性梯度凝胶电泳(polymerase chain reaction-denaturing gradient gel electrophoresis,PCR-DGGE)分析菌群变化,并将两部分结果运用冗余分析(redundancy analysis,RDA)方法进行变化规律分析,发现发酵过程中细菌多样性指数呈先减小后增大的趋势。乳酸、柠檬酸、苹果酸和草酸在发酵过程中是水果酵素的主要有机酸。PCR-DGGE共检测出19条特异性条带,包括7株乳酸菌,2株肠杆菌,1株肠球菌,2株假单胞菌,以及3株不可培养微生物等。RDA表明对柠檬酸生成贡献率较大的菌株分别为Lactobacillus plantarum>uncultured Brevundimonas sp.>Enterobacter xiangfangensis>uncultured Lactococcus sp.,对乳酸生成贡献率较大的菌株分别为L.plantarum>Lactococcus lactis subsp.>E.xiangfangensis>L.lactis subsp.>uncultured Lactococcus sp.。

The purpose of this study was to analyze the changes in the bacterial community composition and organic acids in naturally fermented mixed fruits added with different amounts of brown sugar(fruit to sugar ratio of 1:1,2:1 and 3:1,denoted as A,B and C,respectively).High performance liquid chromatography(HPLC)was used to determine the change of organic acid contents.Polymerase chain reaction-denaturing gradient gel electrophoresis(PCR-DGGE)was used to analyze the changes in bacterial community,and the results were analyzed by redundancy analysis(RDA).It was found that the Shannon-Wiener index first decreased and then increased in the fermentation process.Lactic acid,malic acid,citric acid and oxalic acid were the main organic acids during fermentation.A total of 19 specific bands were detected by PCR-DGGE,including 7 strains of lactic acid bacteria,2 strains of Enterobacter,1 strain of Enterococcus,2 strains of Pseudomonas,and 3 strains of unidentified microorganisms.RDA showed that in terms of their decreasing contribution to organic acid production,the bacteria were ranked as follows:Lactobacillus plantarum>uncultured Brevundimonas sp.>Enterobacter xiangfangensis>uncultured Lactococcus sp.for citric acid production;and L.plantarum>L.lactis subsp.>E.xiangfangensis>L.lactis subsp.>uncultured Lactococcus sp.for lactic acid production.