灰霉病菌拮抗放线菌的筛选鉴定及对草莓的防腐保鲜效果

Identification of Antagonistic Actinomyces Strain against Botrytis cinerea and Effect of Its Fermentation Filtrate on Preservation Quality of Strawberry

为丰富草莓采后病害拮抗菌资源,以草莓灰霉病菌(Botrytis cinerea)为指示菌,采用琼脂块法对草莓根际土壤分离的78株放线菌进行筛选,并测定拮抗效果最强的菌株T3-5的拮抗谱。根据形态学特征、生理生化特性及16S rDNA序列进行鉴定,并初步研究其无菌发酵液对贮藏草莓腐烂发生及果实品质的影响。结果表明:草莓根际土壤分离的菌株T3-5对草莓灰霉病菌具有较强拮抗作用,拮抗圈直径为22.5 mm;对3株常见细菌和6株果蔬采后病原真菌均具有不同程度的抑制效果。该菌株经鉴定为黄暗色链霉菌(Streptomyces xanthopHaeus)。菌株无菌发酵液能够显著降低贮藏草莓腐烂率(P<0.05),延缓果实硬度、可溶性固形物、可滴定酸及VC的降低。研究表明拮抗链霉菌T3-5对贮藏草莓具有良好的防腐保鲜作用,在草莓采后贮藏和生物保鲜中具有潜在的应用价值。

In order to obtain more antagonists for controlling postharvest strawberry disease, Botrytis cinerea was used as an indicator strain to screen antagonistic actinomyces out of 78 strains isolated from strawberry rhizosphere. The inhibitory spectrum of antagonistic strain T3-5 was tested by agar block method, and the effect of its cell-free fermentation filtrate on postharvest decay and quality of fresh strawberry fruits was assessed. The results showed that strain T3-5 had the strongest inhibitory effect on B. cinerea and six other selected postharvest pathogens, and the diameter of inhibitory zone against B. cinerea was 22.5 mm. Based on its morphological characteristics and 16 S r DNA sequence, the antagonistic strain T3-5 was primarily identified as Streptomyces xanthophaeus. Its cell-free fermentation filtrate significantly（P〈0.05） decreased the incidence of strawberry fruit rot. In addition, assays demonstrated that T3-5 filtrate treatment could slow down the decline of postharvest strawberry fruit firmness, soluble solid content, titration acid content and vitamin C content during storage period. Conclusively, the antagonistic strain T3-5 has potential value in biological control against strawberry postharvest diseases.