Interactions of sulfur and methane-oxidizing bacteria in tropical estuarine sediments

The bacterial oxidation of sulfur and methane is central to the biogeochemical processes in sediments such as the tropical mangrove sediments. However, there is a lacuna of information on the seasonal interactions including the influence of monsoons which is a major driver of seasonal change, on sulfur-oxidizing bacteria (SOB) and methane-oxidizing bacteria (MOB), their activity and the environmental variables. To understand these interactions, the analysis was carried out on sediment samples that were sampled monthly for a year from Chorao mangrove, Goa, southwest coast of India. SOB (3.8x10(5)CFU g(-1)) and MOB (0.90x10(5)CFU g(-1)) had maximum average abundance in the surface sediments in the post-monsoon and monsoon season, respectively. The mean sulfur-oxidation activity (SOA) of 2.63mMday(-1) and methane-oxidation activity (MOA) of 110.94mMday(-1) were highest in surface sediments during the post-monsoon season. Generally, the activity of SOB and MOB in surface sediments of post-monsoon was 2.2 times(x) and 2.8x respectively higher than that in the monsoon season. Among the environmental parameters analyzed, protein and sulfide concentrations significantly (p<0.001) influenced SOA and MOA, respectively. There was a significant difference in SOA (p<0.003) and MOA (p<0.036) in surface sediments between the monsoon and the post-monsoon season. During the monsoon season, when the system is a sink of terrestrial/anthropogenic material, the interrelationship of SOB with MOA (r=0.617, p<0.001) and SOB with SOA (r=0.489, p<0.05) aids in maintaining the homeostasis of the system.