Abstract
BackgroundRhizosphere soil is a crucial niche for the diverse beneficial microbial communities in plant-microbe interactions. This study explores the antagonistic potential and diversity of the rhizosphere soil bacteria from commercial tea estates of Assam, India which comes under the Indo-Burma mega-biodiversity hotspot. Rhizosphere soil samples were collected from six different tea estates to isolate the bacteria. The bacterial isolates were subjected to evaluate for the antagonistic activity against fungal pathogens. The potential isolates were investigated for chitinase production and the presence of chitinase gene. The bacterial genetic diversity was studied by Amplified Ribosomal DNA Restriction Analysis (ARDRA) and BOX-PCR fingerprinting.ResultsA total of 217 rhizobacteria were isolated from tea rhizosphere soil, out of which 50 isolates exhibited the potential antagonistic activity against fungal pathogens. Among them, 12 isolates showed extracellular chitinase activity and the presence of chitinase genes. The chitinase genes were sequenced and the analysis of the sequences was performed by using PDB protein databank at the amino acid level. It showed the presence of ChiA and ChiA74 gene in the 6 most potent isolates which are involved in the hydrolysis of chitin. These isolates also exhibited antagonistic activity against all tested fungal pathogens. The diversity of 50 antagonistic bacterial isolates were analyzed through ARDRA and BOX-PCR fingerprinting. Diversity analysis and molecular identification of the rhizosphere isolates revealed that these antagonistic isolates predominantly belonged to the genus Bacillus followed by Enterobacter, Serratia, Lysinibacillus, Pseudomonas, and Burkholderia.ConclusionThe present study establishes that rhizobacteria isolated from the poorly explored tea rhizosphere soil could be a rich reservoir for the investigation of potential antagonistic bacterial candidates for sustainable agricultural and industrial applications.
Highlights
Rhizosphere soil is a crucial niche for the diverse beneficial microbial communities in plant-microbe interactions
Isolation of rhizobacteria A total of 217 rhizobacteria were isolated from rhizosphere soil in six different commercial tea estates of Assam, India
The rhizobacterial isolates were enumerated based on their distinctive colonial morphology
Summary
Rhizosphere soil is a crucial niche for the diverse beneficial microbial communities in plant-microbe interactions. Rhizosphere soil is considered as one of the most active regions in soil that is governed by intense interactions between plant and root-associated microbes. The molecular studies on bacterial diversity have revealed a large richness of species, which promote plant growth and yield, compete for (or inhibit) pathogens, solubilize phosphate, or contribute to nitrogen assimilation in plants [29]. This technological advance has become so pervasive that it is being regularly applied to explore soils and plants of agricultural interest
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