Diversity of culturable bacteria endowed with antifungal metabolites biosynthetic characteristics associated with Tea rhizosphere soil of Assam, India
Abstract Background Rhizosphere soil is a crucial niche for the diverse beneficial microbial communities for 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 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 presence of chitinase gene. The bacterial genetic diversity was studied by ARDRA and BOX-PCR fingerprinting. Results A total of 217 rhizobacteria were isolated from tea rhizosphere soil and 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 sequencing and analysis of the chitinase gene using PDB protein databank at the amino acid level showed the presence of ChiA and ChiA74 gene in the isolates which involved in the hydrolysis of chitin. The analysis showed that 6 most potential isolates exhibited antagonistic activity against all tested fungal pathogens and presence of chitinase genes within their genome. The diversity of 50 antagonistic bacterial isolates were analysed 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. Conclusion The 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.