Potential of pink pigmented methylotrophic bacteria on growth and physiology of cluster bean and soil microbial community

Methylotrophs are one of the prominent microbial community which are known for utilizing methanol as well as carbon sources from various plant metabolic activities and in turn facilitates the host plant growth by synthesizing phytohormones. A pot study was conducted to examine the bio-fertilizing potential of pink pigmented methylotrophic bacteria (PPFM) on cluster bean (Cyamopsis tetragonolaba (L.) Taub and its impact on soil microbial communities. Foliar and soil application modes of treatment was employed for the study. Our results showed that isolated strain from Quisqualis indica leaf was identified as Methylobacterium tardum (strain IHBB) by 16s rRNA gene sequence and phylogenetic analysis confirmed its relationship with other Methylobacterium spp. Soil microbes such as bacterial population (9.25 CFU x 10-6/g), fungal population (70.05 CFU x 10−3/g) and microalgae (9.65 CFU x 10−4/g) were found to be enhanced in 3% of M. tardum (T2) when compared to T1, T3 and control. Soil application of M. tardum exhibited better response on growth, biochemical and yield parameters of cluster bean than foliar application. This study confirms that M. tardum could be a promising candidate as microbial inoculant for plant growth and development as well as a positive driver for enriching the soil microbial community.