Genetic and Functional Diversity Among the Antagonistic Potential Fluorescent Pseudomonads Isolated from Tea Rhizosphere |
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Authors: | Ratul Saikia Rupak K Sarma Archana Yadav Tarun C Bora |
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Institution: | (1) Biotechnology Division, North-East Institute of Science & Technology (CSIR), Jorhat, 785006, Assam, India |
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Abstract: | 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 2099T, P. aeruginosa MTCC 2582T, P. aureofaciens NICM 2026T, and P. syringae MTCC 673T. 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. |
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