Ecology of soil microbes in a tropical mangrove forest of south east coast of India

•This work reports the soil microbial and physicochemical characteristics of mangroves ecosystem.•The relation of soil microbiome and physicochemical characteristics was studied.•The significance of microbial load in mangrove forest is reported.

Present work enumerated nine groups of microorganisms in the soil samples drawn at 10depths from two mangrove sites for four seasons in two years, along with 23 physicochemical characteristics in a mangrove forest. The microbial density was higher in dense mangrove sediments than that in sparse ones. Among the microorganisms, actinobacteria, total heterotrophic bacteria (THB), thraustochytrids, yeasts and fungi were high in dense mangrove sediments. Microbial counts reduced with increasing soil depth. Physical factors displayed profound effect on microbes than chemical factors did. Among the physical factors, the dense mangrove sediment exhibited many fold higher silt, clay, redox potential, lower sand and higher pore water salinity than sparse mangrove sediment did. Among the chemical factors, total organic carbon (TOC) was 52% and soil nitrogen was 4.5% higher in dense mangrove sediment than that in sparse mangrove sediment. This work reiterated significance of mangrove forest for conserving marine microbiota for maintaining carbon and nutrients in coastal sediment.