Molecular insights into cobalt homeostasis in estuarine microphytobenthos: A meta-transcriptomics and biogeochemical...

Meta-transcriptomics data supported by biofilm physico-chemical parameters unravelled the molecular and biochemical processes utilized by multicomponent intertidal biofilms to endure cobalt toxicity. Findings indicated activation of influx (BtuB, ABC-type transporters) and efflux pumps (RND, CZC) to maintain metal ion homeostasis. Enhanced specific activity of antioxidant enzymes namely catalases and peroxidases (KatG, SodA) mitigated oxidative damage. Heightened synthesis of capsular polysaccharide components, specifically uronic acid and carbohydrate via PEP-CTERM sorting system, wzy pathway and glycosyltransferases protected biofilms against cobalt exposure. Despite chlorophyll biosynthesis genes being upregulated, metal toxicity impeded chlorophyll replenishment. Principal pathways associated with iron acquisition (AfuA), energy metabolism (AtpG), general metabolic activities (FruK, NifD, coABC) and central dogma regulation (DPS, AsrR, RRM) were activated to combat cobalt toxicity. This investigation offered novel insights into the regulatory network employed by intertidal microphytobenthic communities for maintaining cobalt homeostasis and underlined the basis for their application as biomarkers for estuarine cobalt pollution.