速冻猕猴桃生产线中耐高渗酵母的分离鉴定

目的旨在明确污染速冻猕猴桃产品加工环节中主要的高渗酵母种类,并且研究污染菌种的耐渗特性,从而在加工中能够预防性地识别和控制高渗酵母污染。方法对酵母基因组5.8S rDNA-ITS区或26S rDNA的D1/D2区两个保守区域进行扩增和测序,确定分离筛选的高渗酵母的种属信息和分布。测定部分菌株在2%、50%、60%(m:V)葡萄糖浓度下的OD600,确定耐糖特性。同时,测定部分菌株在2%和50%(m:V)糖浓度下的产气量。结果在速冻猕猴桃加工环境中共分离筛选到33株高渗酵母,分属于10个酵母种。其中,Hanseniaspora uvarum、Hanseniaspora opuntiae、Candida intermedia和Candida tropicalis是发生频次高的耐高渗酵母种。Lodderomyces elongisporus和Debaryomyces hansenii耐渗性强,能够耐受60%(m:V)葡萄糖;Hanseniaspora opuntiae和Metschnikowia pulcherrima在高糖培养基中产气量大。结论速冻猕猴桃加工车间中分离到潜在污染性的耐高渗酵母,尤其是车间空气中存在多种耐高渗酵母,因此需要加强加工过程中的卫生管理,增加预防性的杀菌措施,保证速冻猕猴桃加工过程的质量安全。

Isolation and identification of osmotolerant yeasts from quick-frozen kiwi fruit processing

Objective To identify osmotolerant yeasts exist in quick-frozen kiwi fruit processing procedures, and to characterize the glucose tolerance and gas production of selected strains which potentially compromise product safety and security. Methods Amplification and sequencing of the yeast 5.8S rDNA-ITS region or D1/D2 region of 26S rDNA were carried out to determine the identity and distribution of the isolated strains. The OD600 were recorded under 2%, 50% and 60% (m:V) glucose concentration to measure osmotic to-lerance of selected strains. Meanwhile, the gas production of selected strains under 2% and 50% glucose were also assayed. Results A total of 33 isolates belonging to 10 genera were identified: Hanseniaspora uvarum, Hanseniaspora opuntiae, Candida intermedia, and Candida tropicalis were repeatedly occurring throughout the processing. Lodderomyces elongisporus and Debaryomyces hanseniic could tolerate 60% (m:V) glucose, and Hanseniaspora opuntiae and Metschnikowia pulcherrima produced a large amount of gas. Conclusion Osmotolerant yeasts were isolated from the workshop of quick-frozen kiwi processing, particularly the air around the workshop contained various species. To assure the processing safety and security of quick-frozen kiwi fruit, the company should intensify sanitary management and implement preventive disinfection procedures.