Isolation, Characterization and Identification of Indigenous Endophytic Bacteria Exhibiting PGP and Antifungal Traits from the Internal Tissue of Sugarcane Crop

Abstract

Using different isolation approaches, 118 endophytic bacteria (beyond N-fixer diazotroph) were isolated collectively from the roots and shoots of three sugarcane varieties Co 1148, CoS 767 and CoJ 64 in this study. Further, these endophytes were tested for their in vitro inhibition against the red rot pathogen (Colletotrichum falcatum). Out of 118, only 29 bacteria were able to show in vitro inhibitory action against the pathogen. Besides inhibiting their mycelial growth, some of these endophytes were able to synthesize various PGP traits such as IAA, phosphate solubilization, siderophore, HCN, ACC deaminase, and ammonia production. These endophytes were found helpful in promoting the growth of the plant in a direct and indirect way. Six bacterial isolates with more than 75% inhibitory activity against the pathogen and PGP attributes were further characterized through 16S rRNA gene sequencing. On the basis of the phylogenetic analysis, the six endophytic antagonists were identified as Bacillus cereus (S8), B. aryabhattai (S12), B. subtilis (S17), B. licheniformis (S26), B. paramycoides (R5), and Pseudomonas aeruginosa (BS-4). This study demonstrated that endophytic bacteria are an untapped source of natural products and can be exploited for yield attributes and red rot control in sugarcane.