Phyllosphere Methylotrophic Microbial Community with Varying Carbon Use Efficiency Promote Soil Fertility and Plant Growth

Plant phyllosphere, through the action of the enzyme pectin methyl esterase, which releases methanol as a byproduct of cell wall metabolism. Methylotrophs methane or methanol as their sole carbon source and reduce GHG emission from the atmosphere. In the present study, phyllosphere methylotrophic microbial community (PMMC) were isolated from the phyllosphere of rabi season crops. Out of the 16 PMMC isolates, six crops PMMC that is - Chickpea (POL 01), Chickpea (PUSA 3043), Chickpea (PUSA 3057), Radish (Pusa Himani), Beetroot (Crimson Globe) and Broad bean (Pusa Sumit) were selected based on their growth in Nitrate mineral salt medium (NMS) supplemented with 1% methanol. PMMC isolates were screened for plant growth promoting traits namely N2-fixation, P-solubilization, K-solubilization, and Zn-solubilization. PMMC of Beetroot and Raddish performed best compared to other PMMC in terms of their PGPR traits. The methanol use efficiency of six PMMC was also measured in terms of its conversion to CO2 which ranged from 3.74-7.48 mg of CO2/21 days. Based on the mesocosm experiment results, soil amended with the PMMC of Radish (Pusa Himani) significantly (P< 0.05) improved the available N, P, K and Soil organic carbon percentage at 21 days of incubation as compared to non-inoculated PMMC soils. The positive relationship between soil enzyme activities like phenol oxidase (POX), FDA hydrolase, β-glucosidase and dehydrogenase activities involved in C cycling in soil underlines the role of PMMC of different crops in plant growth promotion and sequestration of methane in the soil as microbial necromass.