冬季甜瓜腐烂病原菌的分离与鉴定

从冬季贮存甜瓜的腐烂组织中分离病原菌，并对其类型进行检测分析。利用马铃薯葡萄糖琼脂(PDA)培养基和溶菌肉汤(LB)培养基培养，依据微生物形态特性，真菌的26S rRNA 序列和细菌的16S rRNA 序列比对以及系统发育进化分析等分子生物学方法，共分离到22 株菌种，其中真菌13 株：包括青霉2 株、链格孢4 株、白地霉4 株、酵母3 株(梅奇氏酵母2 株、毕赤酵母1 株)；细菌9 株：包括沙雷氏菌5 株，丁香菌1 株，克雷伯菌、肠杆菌和芽孢杆菌各1 株。根据26S rRNA D1/D2 区序列比对和系统进化树结果显示，两株酵母菌121 和122 可能是梅奇氏酵母属潜在的新种。青霉和链铬孢是甜瓜腐烂致病菌，白地霉和沙雷氏菌是人体致病菌，表明目前甜瓜贮存方法需要进一步改进和完善。

Isolation and Identification of Decay-inducing Pathogens from Melon Stored in Winter

Isolation and identification of pathogens from the decayed tissues of melon stored in winter were carried out using LB (lysogeny broth) and PDA (potato dextrose agar) media. Based on morphological characteristics, D1/D2 region of 26S rRNA sequences for fungi, 16S rRNA gene sequences for bacteria and phylogenetic trees, a total of 22 strains were isolated. Thirteen of them belonged to the family of fungi, including 2 strains of the genus Penicillium, 4 strains of the genus Alternaria, 4 strains of the genus Geotrichum, and 3 yeast strains (2 strains of the genus Metschnikowia and 1 strain of the genus Pichia); the rest were all bacteria, including 5 strains of Serratia. sp, 1 strain of cloves. sp, 1 strain of Klebsiella. sp, 1 strain of Enterobacter. sp and 1 strain of Bacillus. sp. The results of 26S rRNA and phylogenetic tree analysis revealed that 2 isolates (strain 121 and strain 122) were yeast, which may be a new species belonging to the genus Metschnikowia. Alternaria and Penicillium were pathogenic fungi for melon, and Geotrichum and Serratia. sp were pathogens for human. Therefore, these investigations demonstrate that current conditions for winter storage of melon should be improved.