苹果腐败霉菌的拮抗酵母菌筛选鉴定及拮抗机理初探

从苹果果皮中筛选出对引起苹果采后病害的扩展青霉(Penicillium expansum)、互隔交链格孢霉(Alternaria alternata)和黑曲霉(Aspergillus niger)具有拮抗作用的酵母菌,并初步研究其拮抗机理。结果表明:筛选得到两株可以同时拮抗三种腐败霉菌的拮抗酵母菌Y4和Y9,根据酵母菌菌落性状、生理生化特征并结合分子生物学的分析结果,鉴定为Candida railenensis和Aureobasidium pullulans,其中A.pullulans为类酵母真菌。C.railenensis的最佳拮抗浓度为10⁹ CFU/mL,对P.expansum、A.alternata和A.niger的菌丝生长、孢子萌发和芽管生长均有显著(p<0.05)的抑制作用。扫描电镜观察到C.railenensis能够包围和吸附腐败霉菌孢子,与它们竞争营养与空间,此外还能够吸附P.expansum菌丝体与其直接作用。C.railenensis的主要抑病机理是营养与空间竞争,并且其生防效果的发挥是多种方式共同作用的综合结果。

Screening,identification and antagonistic mechanism of antagonistic yeasts against the spoilage mould of apple

In order to control postharvest disease of apples,Penicillium expansum,Alternaria alternata and Aspergillus niger were used as indicator strains to screen antagonistic yeasts isolated from apple peel. The antagonistic mechanism of yeast was also preliminarily studied. Based on its morphological characteristics,physiological and biochemical characteristics and ITS sequences,the antagonistic yeast strains Y4 and Y9 were identified as Candida railenensis and Aureobasidium pullulans,in which A. pullulans was a fungus like yeast. Optimal concentration of C. railenensis was 109 CFU/mL,and it could significantly inhibit the mycelia growth,spore germination and germ tube growth of P. expansum,A. alternata and A. niger. Scanning electron microscopy showed that C. railenensis was able to surround and adsorb the spore of spoilage fungi,compete with them for nutrition and space,and also adsorb P. expansum mycelia and thus interact directly with them. Competition nutrition and competition space were the main mechanisms of C. railenensis,and its biocontrol effect was a combined result of many ways.