Genetic diversity and phylogeny of pink-pigmented facultative methylotrophic bacteria isolated from the phyllosphere of tropical crop plants

Genetic diversity of pink-pigmented facultative methylotrophic bacteria belonging to the genus, Methylobacterium, was assessed using 16S ribosomal RNA (rRNA) gene sequencing, amplified ribosomal DNA restriction analysis (ARDRA), and differential carbon-substrate utilization profile in the phyllosphere of cotton, maize, sunflower, soybean, and mentha plants. Methylobacterium populi, Methylobacterium thiocyanatum, Methylobacterium suomiense, M. aminovorans, and Methylobacterium fujisawaense were identified to colonize the phyllosphere of these crop plants. Among these, M. populi found to be the dominating species followed by M. aminovorans. The diversity indices like Shannon index of diversity, Pielou index of evenness, and Margalef index of richness calculated based on combined data of ARDRA, 16S rRNA gene sequence, and differential carbon-substrate utilization revealed that sunflower leaves showed richest methylobacterial diversity, followed by soybean, while cotton and mentha leaves recorded the lowest diversity. The outcome of this study indicates that diversity of Methylobacterium in phyllosphere depends upon the host plant species colonized.