Biotechnology Division, North-East Institute of Science & Technology (CSIR), Jorhat, 785006, Assam, India.
Curr Microbiol. 2011 Feb;62(2):434-44. doi: 10.1007/s00284-010-9726-y. Epub 2010 Aug 6.
Twenty-five fluorescent pseudomonads from rhizospheric soil of six tea gardens in four district of Upper Assam, India were isolated and screened for antagonistic activity against fungal pathogens such as Fusarium oxysporum f. sp. raphani (For), Fusarium oxysporum f. sp. ciceri (Foc), Fusarium semitectum (Fs), and Rhizoctonia solani (Rs); and bacterial pathogens-Staphylococcus aureus (Sa), Escherichia coli (Ec), and Klebsiella pneumoniae (Kp). Most of the isolates exhibited strong antagonistic activity against the fungal pathogens and gram-positive bacterium i.e. Staphylococcus aureus. Productions of siderophore, salicylic acid (SA), hydrogen cyanide (HCN), and cell wall-degrading enzyme (chitinase) were studied to observe the possible mechanisms of antagonistic activity of the isolates. Correlation between the antagonistic potentiality of some isolates and their levels of production of siderophore, salicylic acid, and hydrogen cyanide was observed. Out of the 25 isolates, antibiotic-coding genes, 2,4-diacetylphloroglucinol (DAPG) and pyoluteorin (PLT) were detected in the isolates, Pf12 and Pf373, respectively. Genetic diversity of these fluorescent pseudomonads were analyzed with reference to four strains of Pseudomonas fluorescens NICM 2099(T), P. aeruginosa MTCC 2582(T), P. aureofaciens NICM 2026(T), and P. syringae MTCC 673(T). 16S rDNA-RFLP analysis of these isolates using three tetra cutter restriction enzymes (HaeIII, AluI and MspI) revealed two distinct clusters. Cluster A comprised only two isolates Pf141 and 24-PfM3, and cluster B comprised 23 isolates along with four reference strains.
从印度上阿萨姆邦四个地区六个茶园的根际土壤中分离出 25 株荧光假单胞菌，对其拮抗活性进行了筛选，以对抗真菌病原体，如尖孢镰刀菌（For）、菜豆壳球孢菌（Foc）、半纤维素镰刀菌（Fs）和立枯丝核菌（Rs）；以及细菌病原体金黄色葡萄球菌（Sa）、大肠杆菌（Ec）和肺炎克雷伯菌（Kp）。大多数分离株对真菌病原体和革兰氏阳性菌金黄色葡萄球菌表现出强烈的拮抗活性。研究了铁载体、水杨酸（SA）、氰化氢（HCN）和细胞壁降解酶（几丁质酶）的产生，以观察分离株拮抗活性的可能机制。观察了一些分离株的拮抗潜力与其铁载体、水杨酸和氰化氢的产生水平之间的相关性。在 25 个分离株中，Pf12 和 Pf373 分别检测到抗生素编码基因 2,4-二乙酰基邻苯二酚（DAPG）和吡咯并菌素（PLT）。荧光假单胞菌的遗传多样性与荧光假单胞菌 NICM 2099（T）、铜绿假单胞菌 MTCC 2582（T）、黄单胞菌 NICM 2026（T）和丁香假单胞菌 MTCC 673（T）的四个菌株进行了分析。使用三种四切割限制酶（HaeIII、AluI 和 MspI）对这些分离株进行的 16S rDNA-RFLP 分析显示出两个不同的聚类。聚类 A 仅包含两个分离株 Pf141 和 24-PfM3，聚类 B 包含 23 个分离株和四个参考菌株。
