Department of Microbiology, Guru Nanak Dev University, Amritsar, 143005, Punjab, India.
Microbiol Res. 2020 Aug;237:126478. doi: 10.1016/j.micres.2020.126478. Epub 2020 Apr 18.
The emergence of resistance among fungal phytopathogens poses a biggest threat across the world. Streptomyces are a group of spore-forming Gram + ve bacteria and prolific producers of secondary bioactive metabolites which have been used as biocontrol agents against phytopathogens and also known for plant growth promotion. The current study identified a potent isolate M4 from soil with broad spectrum antifungal activity against different fungal phytopathogens. The isolate was identified as a Streptomyces sp. on the basis of cultural, morphological, physiological, biochemical and phylogenetic characteristics. 16S rRNA gene sequence of M4 showed 100 % similarity with three Streptomyces spp. i.e. Streptomyces plicatus NBRC 13071 T (AB184291), Streptomyces rochei NBRC 12908 T AB184237 and Streptomyces enissocaesilis NRRL-B-16365 T (DQ026641). However, phenotypic and phylogenetic analysis concluded that M4 represents a novel sp. within the genus Streptomyces. One of the two antifungal compounds purified from Streptomyces M4 was identified as salvianolic acid B. To our knowledge, the present study is the first work reporting purification and characterization of salvianolic acid B from Streptomyces and its broad spectrum antifungal activity against different fungal phytopathogens viz. Alternaria spp., Fusarium spp., Colletotrichum spp., Cladosporium herbarum and Botrytis cineria. Salvianolic acid B was found to be photostable, thermostable (up to 70 °C) and non-mutagenic in nature and might be developed as safe biofungicide to control phytopathogens.
真菌病原菌的耐药性的出现是全世界面临的最大威胁。链霉菌是一群革兰氏阳性孢子形成细菌，是次生生物活性代谢物的丰富生产者，这些代谢物已被用作针对植物病原菌的生物防治剂，并且也以促进植物生长而闻名。本研究从土壤中分离出一种具有广谱抗真菌活性的有效分离株 M4，可以对抗不同的真菌病原菌。该分离株基于文化，形态，生理，生化和系统发育特征被鉴定为链霉菌属。M4 的 16S rRNA 基因序列与三种链霉菌属即链霉菌plicatus NBRC 13071 T（AB184291），罗氏链霉菌 NBRC 12908 T AB184237和 enissocaesilis NRRL-B-16365 T（DQ026641）具有 100％的相似性。然而，表型和系统发育分析表明，M4 代表链霉菌属中的一个新种。从链霉菌 M4 中纯化的两种抗真菌化合物之一被鉴定为丹酚酸 B。据我们所知，本研究首次报道了从链霉菌中纯化和表征丹酚酸 B 及其对不同真菌病原菌（即交替单胞菌，镰刀菌，炭疽菌，枝孢菌和灰葡萄孢）的广谱抗真菌活性。丹酚酸 B 被发现具有光稳定性，热稳定性（高达 70°C）和非诱变性质，并且可能被开发为安全的生物杀菌剂来控制植物病原菌。
