某企业生产的一批茶饮料中发现某些产品变质,3份样品出现pH值下降,或产气胀罐现象,或有肉眼可观察到浑浊、变色等感官指标的变化。检测发现引起腐败变质的主要是细菌,其数量≥104 CFU/mL,4株主要污染菌菌株经16S rDNA序列比对,鉴定为假单胞菌属(Pseudomonas sp.)、肠杆菌属(Enterobacter sp.)、芽胞杆菌属(Bacillus sp.)和短芽孢杆菌(Brevibacillus sp.)。样品中还有数量很低(101～102 CFU/mL左右)的霉菌检出,经形态观察初步鉴定为交链孢霉(Alternaria spp.)、枝孢霉(Cladosporium spp.)、曲霉(Aspergillus spp.)和青霉(Penicillium spp.)。该案例中霉菌虽然不是主要的腐败变质菌,但是其菌相组成与空气中主要的霉菌菌相一致,显示该污染的源头可能是空气,细菌的组成也能支持这个推论。实践中,通过更换无菌空气过滤器,确实解决了污染问题,证实了该推论。

One lot of tea drinks were found deteriorated,with pH decrease,gas production,swell can,visible deposition and discoloration.Over 104 CFU/mL bacteria were detected in 3 samples.Four main bacteria were isolated and identified by 16S rDNA sequence blast as Pseudomonas sp.,Enterobacter sp.,Bacillus sp.,and Brevibacillus sp.A few fungi were also detected in all 3 samples with amount of 101~102 CFU/mL.They were identified primarily as Alternaria spp.,Cladosporium spp.,Aspergillus spp.,and Penicillium spp.In this case,although fungi were not the main putrefactive organisms,but its unique flora were just the same as those of air,indicating that air was probably the pollutant source.And the bacterial flora also supported this deduction.In practice,the pollution was solved by replaced the air filter to confirm the conclusion.