Plant growth promoting microbes with antibiotic resistance; can that be used together

Abstract

The antibiotic application reduces the microbial count of pathogenic microbes along with beneficial plant growth promoting bacteria (PGPB). This can be avoided if PGPB has antibiotic resistance. Thirty bacterial isolates were found from nutrient-rich alkaline soil, associated with phosphate and potassium solubilization and IAA production potential. Twelve isolates were shortlisted and the antibiotic sensitivity of the bacterial isolates was tested against eight antibiotics using the disc diffusion technique. Based on various physiological tests, compatibility and 16S rRNA sequence analysis, two PGPB Bacillus megaterium (M-08) and Bacillus aryabhattai (M-24) were identified. Both the isolates were positive for starch hydrolysis, catalase activity, acid and gas production, urease and gelatin liquefaction tests. Isolate (M-20) had the highest PSI of 6.0. M-26 had the highest KSI of 5.6. M-08 and M-24 were antagonistic against phytopathogenic R. solani. The present study indicated the presence of diverse P and K solubilising bacteria in the tomato rhizosphere, with IAA production potential and antibiotic resistance. These bacterial isolates can serve as potential plant growth promoters as they showed an increase in N, P and K uptake in the plant. The research tried to bring up a hypothesis of antibiotic selective plant growth promoters or biocontrol agents and their benefit in acclimatization and establishment in soil despite the microbicidal applications. This method can be used worldwide, to eradicate phytopathogens, while leaving the beneficial PGP microbes in rhizospheres.