在对草莓的病源微生物污染调查中发现蜡样芽孢杆菌具有高的检出率。为比较不同温度和不同包装方式的草莓表面蜡样芽孢杆菌数量的变化情况,测定了7℃、15℃、25℃、30℃的温度条件下,采用保鲜盒包装和保鲜膜包装方式的草莓表面蜡样芽孢杆菌生长数据;选用Baranyi Roberts模型为初级模型,拟合不同温度和不同包装方式的草莓中蜡样芽孢杆菌生长曲线,并对模型进行验证。结果显示,7℃冷藏的蜡样芽孢杆菌均增长缓慢而与包装方式无关;15℃低温贮藏过程中,膜装与盒装延滞期基本相同,但膜装比盒装降低了0.7 lg cfu/g的生长势,说明保鲜膜在此温度下有一定的抑菌作用;在25℃、30℃储藏下两种包装方式的比生长速率和延滞期基本相同,蜡样芽孢杆菌在42 h后分别增长了2.9 lg cfu/g、3.2 lg cfu/g,表明贮藏温度是影响蜡样芽孢杆菌的主要因素。因此在高温条件下蜡样芽孢杆菌会带来潜在的食用安全风险。本研究结果为微生物定量风险评估提供重要信息。
[Objective] This study aimed to explore an effective method for rapid salt- extraction of high-quality genomic DNA from dried seeds of plants. [Method] Seeds of seven varieties of crops were ground into powder. A hundred milligrams of seed powder was added to extracting solution for high salt-extraction of genomic DNA. The yield and quality of extracted DNA were determined by using ultramicro UV/Vis spectrophotometer detection method, PCR and restriction enzyme digestion. [Result] About 619.67-1 811.21 ng of genomic DNA was extracted from per 100 mg of dried seed powder of seven varieties of conventional crops. A260/A280 ratios of the obtained DNA solution all ranged from 1.87 to 2.07, the purity and quality of PCR were suitable for PCR and restriction enzyme digestion. Clear target bands of specific endogenous gene fragments of seven varieties of crops were amplified by PCR, and the obtained DNA could be fully digested with EcoRV and Hindlll.[Conclusion] This method could be used for rapid extraction of high-quality genomic DNA from dried seeds.
