一株辣椒尖孢炭疽病菌拮抗菌株的分离鉴定与发酵条件优化

 为了探寻辣椒尖孢炭疽病的生防药剂，从而控制该病在辣椒生产上的扩散。以辣椒尖孢炭疽病菌（Colletotrichum acutata）为指示菌，从浏阳河风光带土样中分离筛选出6株拮抗放线菌株，其中菌株ND045对指示菌的拮抗效果最好，菌丝生长抑制率高达71.6%。经形态观察、培养性状、生理生化鉴定，并结合16S rDNA序列分析，将ND045菌株鉴定为吸水链霉菌（Streptomyces hygroscopicus）。抗菌谱研究表明，该菌株对稻瘟病菌(Magnaporthe oryzae)、辣椒疫霉病菌(Phytophthora capsici)、黄瓜枯萎病菌（Fusarium omysporum）和辣椒白绢病菌（Sclerotium rolfsii）都具有较强的拮抗作用,抑菌率达40.58%～72.00%。通过单因子变量法和均匀设计法对菌株ND045进行发酵条件研究,结果表明,其最佳的发酵条件为：15 g大米粉、5 g大豆粉、0.5 g MgSO₄、0.01 g FeSO₄·7H₂O、1.5 g NaCl、水1 000 mL、30℃、pH 8。经优化后，菌丝生长抑制率最高达到82.61%，比优化前提高了11.01%。该研究结果为辣椒尖孢炭疽病的生物防治提供科学依据。

Isolation, identification and optimizing fermentation conditions of an antagonistic strain against Colletotrichum acutata

In order to explore biocontrol agents to control pepper anthracnose disease spread in pepper production.Six antagonistic actinomycetes strains were isolated from the cultivated soil samples of Liuyang River Scenic Belt,among which ND045 strain was exhibited the highest antagonistic activity against Collectotrichum acutata and showed the inhibition rate of 71.6%.The ND045 was identified as Streptomyces hygroscopicus according to the morphology,culture characteristics,physiological and biochemical tests and 16S rDNA analysis.Further antimicrobial spectrum of ND045 was tested against Magnaporthe grisea,Phytophthora capsici,Fusarium omysporum and Sclerotium rolfsii and showed the inhibition rate between 40.58% and 72.00%.The optional fermentation conditions for antibacterial substance production of ND045 were rice flour 15.0 g,soybean flour 10 g,MgSO4 0.5 g,FeSO4·7H2O 0.01 g,NaCl 1.5 g,water 1 000 mL,fermentation temperature 30℃ and pH at 8 through one-variable method and uniform design.After optimization,the inhibition rate of mycelial growth was up to 82.61%,increased for 11.01% more than before.The results provide scientific evidence to pepper anthracnose biocontrol.