Mangroves are considered dynamic and complex ecosystems that depend on various metabolic activities of microorganisms, especially bacteria. In recent years, these ecosystems have suffered ongoing events of anthropogenic disturbance, especially the discharge of heavy metals from industrial wastewaters, which have pushed bacterial community to develop adaptation mechanisms to these disturbance events.
The aim of this study was to determine the main mechanisms of resistance to heavy metals present in the bacterial communities that inhabit disturbed mangrove sediments and to determine the main effect over sulfate reduction pathways.
It was found that czc genes related to RND efflux transports and cusA genes, which, codified for a Cation Diffusion Protein, are associated to mangrove sediments with high levels of metals. Through metabolic reconstruction, both from metagenomic dataset and inferred by taxonomic distribution, it could be found that bacteria members related to the dissimilative sulfur cycle pathway were more abundant in samples with high levels of metals, and the assimilative pathway is present in higher abundance when metal levels decrease.
It can be concluded based on these findings that it is necessary to maintain the balance in SRB, since genes related to the dissimilative sulfate reduction pathway will produce more sulfide gas, making the environment toxic and affecting bacteria associated to the assimilative sulfate reduction pathway. As a secondary effect, it will produce soil infertility, directly affecting the surroundings human populations.