ABSTRACT
Abstract: This study evaluated root endophyte bacteria and rhizobacteria in terms ofmultifaceted plant growth promotion (PGP) traits and antagonistic potential against majorfungal pathogens of rice (viz. Rhizoctonia solani, Bipolaris oryzae, Pyricularia oryzae,Ustilaginoidea virens and Sarocladium oryzae). Twenty bacterial isolates from each group(viz. endorhiza and rhizosphere) were isolated from different rice types of North EastIndia. Cultivated rice types were Upland rice (Mima, Kochi and Minil), Lowland HYV rice(Ranjit and Jaya) and Lowland scented rice (Keteki Joha and Kunkuni Joha). Thepopulation of rhizospheric bacteria was higher than the endophyte isolates. Thepopulation counts of endophyte bacteria were the highest in scented rice cultivar(Kunkuni Joha) and for rhizobacterial isolates; the population density was maximum inthe lowland HYV rice (Jaya). The endophytes were more efficient than the rhizobacteria interms of the activity of cellulase, pectinase, ACC-deaminase, production of IAA- likesubstances, solubilization of zinc and mineralization of organic phosphates. In contrast,the rhizobacterial isolates were more efficient in solubilization of inorganic phosphatesand antagonism against major rice fungal pathogens. Through 16S rDNA sequenceanalysis, the promising rhizobacterial isolates showing antagonism against all the fungalpathogens were identified as Brevibacillus reuszeri 12R, Lysinibacillus xylanticus 48R,Bacillus megaterium 58R and Serratia marcescens 79R. These results suggest that the rootbacterial endophytes and rhizobacteria characterized in this study could be successfullyused to promote plant growth and induce fungal resistance in rice plants and can be usedas bioinoculants for enhancing rice growth in the acid soil regions.