一株感染家蚕的高致病性白僵菌的筛选及发酵条件优化

Screening and fermentation optimization of a highly pathogenic Beauveria bassiana strain infecting silkworm larvae

摘要:

【背景】球孢白僵菌是一种重要的昆虫病原真菌，通过侵染幼蚕可制备白僵蚕。白僵蚕中的生物活性物质在医疗、保健品及化妆品行业有着广泛的应用。【目的】从7株不同来源的白僵菌中筛选获得高毒力白僵菌并优化其发酵条件，为制备白僵蚕提供优质的菌种资源。【方法】从不同白僵蚕体内分离获得7株白僵菌菌株(SDJC-1、SDJC-2、SDJC-3、GXHC-1、SDND-BB、AT-3006和SQJC-1)，通过生物学特性观察、产蛋白酶和几丁质酶活力分析及对家蚕的致死力等研究，筛选得到一株致病力高、性状优异的白僵菌株，并对其最适发酵条件进行探索。【结果】菌株SDJC-3的生物学性状优异，产孢量较高，家蚕致死率达75%，其制备的白僵蚕成品个头大且饱满，横截面丝腺环清晰，品质较好。通过对菌株SDJC-3进一步进行发酵优化，发现其最适生长温度为27℃、最优发酵转速为180 r/min、最适的发酵液体积占比为1/5(250 mL培养瓶)。【结论】本研究将为人工利用白僵菌制备白僵蚕及提高其产量和品质提供理论基础。

Abstract:

[Background] Beauveria bassiana, a major entomopathogenic fungus, infects silkworm larvae, producing the white muscardine silkworm Bombyx Batryticatus. The bioactive substances in Bombyx Batryticatus are widely used in medical, healthcare, and cosmetic industries. [Objective] In order to provide high-quality strain resources for the preparation of Bombyx Batryticatus, a highly pathogenic B.bassiana strain was screened from 7 B. bassiana strains from different samples of Bombyx Batryticatus, and the fermentation conditions of this strain were optimized. [Methods] We isolated 7 B. bassiana strains (SDJC-1, SDJC-2, SDJC-3, GXHC-1, SDND-BB, AT-3006 and SQJC-1) from different samples of Bombyx Batryticatus. Based on the results of biological characteristics, protease and chitinase activities, and the lethality in silkworm, a strain with high pathogenicity and excellent traits was screened out. Moreover, the fermentation conditions of this strain were optimized. [Results] The strain SDJC-3 had excellent biological characteristics, high sporulation, and the lethal rate of 75% to silkworm. The Bombyx Batryticatus prepared with SDJC-3 was large and plump and had clear ring of silk gland in the cross-section, exhibiting good quality. The optimum fermentation conditions of SDJC-3 were 27 ℃ of the temperature, 180 r/min of the rotational speed, and 1/5 of the broth volume ratio (250 mL culture flask). [Conclusion] The findings of this study provide a theoretical basis for the use of B.bassiana to prepare and improve the yield and quality of Bombyx Batryticatus.