Buffered peptone water (BPW) is an enrichment broth of common use for isolating and cultivating microbes.In order to understand the effect of enrichment time of BPW on microbial community structure, contaminated microbes on the surface of chilled fresh chicken were taken as research objects, 20 chilled fresh chicken samples from supermarkets in Hangzhou were collected and enrich microbes in 0, 2, 6, 12, 24 h respectively with BPW to test the changes of total microbial colonies, and analyze the effect of different enrichment time on the salmonella's checking out rate.Two of the samples with different BPW enrich time were selected to extract microbial genomic DNA and respectively analyzed the bacterial community structure changes using DGGE analysis and high-throughput sequencing.The results showed that the total colonies increased with increasing enrichment time, and it increased significantly in 6h (P＜0.01), and the difference between 24 h and other times was extremely significant (P＜0.01). Salmonella's detection rate increased in first 0-12 h, and it increased with the extended enrich time, among them the detection rate at 12 h stage was the highest, 40％, and decreased at 24 h, 15％.The results of DGGE results showed that bands that enriched in 0-12 h were rich, while the ones reduced in 24 h, as compared with those enriched in 0-12 h the bacterial community structure had different clusters.The high-throughput sequencing tests showed that at phylum level Proteobacteria and Firmicutes were the dominant bacterial phylum, accounted for more than 85％level;and after enriched by BPW in 24 h, the bacterial community structure changed greatly, the relative abundance of Proteobacteria reduced, the relative abundance of Firmicutes, Fusobacteria, and Bacteroidetes increased.At the genus level, the dominant bacteria mainly included Acinetobacter, Shewanella, Pseudomonas, and Psychrobacter enriched with BPW within 12 h, however, before BPW enrichment bacteria with relative low abundance as Peptostreptococcus, Fusobacterium, Proteus, Vagococcus, Bacteroides and Morganella had become the dominant bacteria enriched with BPW after 24h.It can be explained that the enrichment time of BPW had significant influence on the number of microorganisms and bacterial community structure, therefore, an appropriated enrichment time should be selected before the enrichment.%缓冲蛋白胨水 (Buffered peptone water, BPW) 是常用于微生物分离培养的增菌液, 为了解BPW增菌对微生物结构的影响, 以冷鲜鸡污染微生物为研究对象, 在杭州超市采集20只冷鲜鸡样品, 分别用BPW增菌0、2、6、12、24 h, 检测菌落总数的变化, 分析不同增菌时间对沙门氏菌检出率的影响.并选择2只冷鲜鸡不同增菌时间的BPW增菌液, 提取细菌基因组DNA, 分别用DGGE分析和高通量测序分析其菌群结构变化.结果显示, 菌落总数随增菌时间增加而增加, 增菌6 h后极显著增加 (P＜0.01), 增菌24 h与其他时间差异极显著 (P＜0.01);沙门氏菌检出率在BPW增菌的前0～12 h增加, 随着增菌时间的延长而增加, 其中增菌12 h阶段检出率最高, 为40％, 而在24 h时下降, 为15％.DGGE结果显示, 增菌0～12 h条带丰富, 24 h条带减少, 与增菌0～12 h的菌群结构有显著不同的聚类.高通量测序显示在门的水平上, 变形菌门 (Proteobacteria) 和厚壁菌门 (Firmicutes) 是冷鲜鸡表面优势菌门, 占85％以上;在BPW增菌24 h后, 菌群结构发生较大变化, 变形菌门相对丰度降低, 厚壁菌门 (Firmicutes) 、梭杆菌门 (Fusobacteria) 、拟杆菌门 (Bacteroidetes) 丰度增加.在属水平上, BPW增菌12 h以内, 优势菌主要为不动杆菌属 (Acinetobacter) 、希尔氏菌属 (Shewanella) 、假单胞菌属 (Pseudomonas) 、嗜冷杆菌属 (Psychrobacter), 而BPW增菌24 h后, 在未增菌前, 相对丰度较低消化链球菌属 (Peptostreptococcus) 、梭杆菌属 (Fusobacterium) 、变形杆菌属 (Proteus) 、漫游球菌属 (Vagococcus) 、拟杆菌属 (Bacteroides) 和摩根氏菌属 (Morganella) 成为主要的优势菌.由此说明BPW增菌时间对沙门氏菌的检出率、微生物数量和菌群结构有显著的影响, 在前增菌时应选择合适的增菌时间.
展开▼
