稻瘟病拮抗菌NK413的鉴定及抑菌效果

菌株NK413是从黑龙江省农田土壤中分离得到的一株放线菌,为明确其分类地位及在植物病害生物防治中的应用潜力,采用多相分类法对其进行鉴定,并采用孢子萌发抑制法、菌丝生长速率法、杯碟法考察了NK413菌株及其代谢产物对稻瘟病菌的抑菌效果及作用方式。结果表明:菌株NK413的形态特征、生理生化特征与小白链霉菌(Streptomyces albulus)接近,细胞壁类型为Ⅰ型、磷脂脂肪酸成分符合链霉菌属特征。16S rDNA全长为1 614 bp,与小白链霉菌亲缘关系最近,因此将NK413定名为小白链霉菌(S.albulusNK413)。NK413对稻瘟病菌孢子萌发和菌丝生长的抑制作用较强,原液对稻瘟病菌的抑菌圈直径达30 mm,无菌发酵滤液稀释1倍对孢子萌发的抑制率为100%,稀释5倍时对菌丝生长的抑制率为100%。抗菌谱广,具有较好的开发前景。

Identification of the antagonistic strain NK413 and its inhibitory effects on Magnaporthe oryzae

The strain NK413 was an antagonistic actinomycete, which was isolated from the soils in Heilongjiang. To provide basis for clarifying its taxonomic status and potential ability in field biocontrol, the multiphase taxonomy was carried out and three test methods, including cylinder plate method, mycelium growth rate method and hanging drop method, were used for evaluating its inhibitory activities and modes of NK413 on Magnaporthe oryzae in the laboratory. The results showed that its morphological properties, culture characteristics, physiological and biochemical characteristics were similar to those of Streptomyces albulus, and its cell wall composition was type I, and its phospholipid fatty acids were consistent with the characters of Steptomyces genus. In addition, the full length of 16S rDNA of the strain NK413 was 1 614 bp, while the homology and clustering analysis indicated that it belonged to S. albulus. Thus, NK413 was identified as Streptomyces albulus NK413. The antagonistic tests showed that NK413 had strong inhibitory activity on the growth of M. oryzae. The inhibitory zone reached 30mm in diameter, and it could strongly inhibit spore germination and mycelial growth of M. oryzae. The inhibition rate of germination reached 100%, when the fermentation was diluted (1∶1), but the hyphal growth was also inhibited by 100% by 1∶5 dilution. The antagonistic spectrum of NK413 was broad. This work suggested the potential ability of the stain NK413 for biocontrol of M. oryzae.