一起饮料微生物污染的鉴定报告

The Identification Conclusion of a Drink Case with Microbial Contamination

摘要: 目的：从一起污染的饮料中分离未知微生物并对其进行种类鉴定。方法：将分离出的微生物接种于人工培养基上培养，肉眼观察其菌落特征；挑取部分菌落用棉兰染色，镜下观察其形态；用DNA提取试剂盒提取其总DNA，并以此为模板，PCR方法扩增其ITS区基因片段，将该基因片段纯化后，由测序公司对其进行序列测定；将测序结果用BLASTn工具进行比对，找出其序列的相关菌种；最后用MEGA5.1软件对该测定序列菌种及其序列相关菌种进行进化分析。结果：肉眼菌落特征、镜下形态观察结果显示该未知微生物属真菌；ITS区测序及BLASTn比对结果显示其为黄曲霉菌，该未知菌与黄曲霉菌同源性高达94%~ 95%；进化树构建结果显示其与黄曲霉菌在同一分支上。结论：污染该饮料的未知微生物为黄曲霉菌。

Abstract: Objective: To isolate and identify the unknown microbes from the contaminated drink. Methods: With the naked eye observation of colony characteristics of isolated microorganisms inoculated in artificial culture medium, observation of colony morphology selected for staining in Medan under the microscope. The total DNA was extracted by DNA extraction kit, and used as the template, the PCR method was used to amplify the ITS gene fragment of this gene fragment, purified, sequenced by sequencing company, then the sequencing results were compared with the BLASTn tool, to find out the sequence of related strains, finally, the sequence of strains and sequence related strains in phylogenetic analysis based on the MEGA5.1 software. Result: The bacterial colony characteristics observed by naked-eye and the morphological characteristics observed microscopically show that the unknown microbe belongs to fungi; BLASTn comparison results of ITS sequence show that the unknown microbe is Aspergillus flavus, the similarity of them is 94% - 95%, and the phylogenetic tree reconstructed based on ITS shows that it is in the same clade as Aspergillus flavus. Conclusion: The unknown microbe in the drink is Aspergillus flavus.