Identification of microbial groups and functional genes associated with greenhouse gas emissions in prawn farms

Understanding microbial associations with greenhouse gas (GHG) emissions is essential for promoting climate-friendly prawn production, yet it remains largely unexplored. To examine microbial-GHG relationships, this study analysed CO₂, CH₄, and N₂O emissions, characterised microbial communities, and measured the abundances of key functional genes (mcrA, pmoA, amoA, and nosZ) in water and sediment from Bangladeshi prawn farms. Results showed that microbial richness was positively correlated with CO₂ and N₂O emissions but negatively with CH₄ emissions. Methanogenic archaea, most abundant in high-salinity farms, were positively associated with CH₄ flux; however, their negative relationship with CO₂ emission appeared insignificant. Conversely, the negative correlation between the relative abundance of anaerobic methanotrophs (ANME) and CH₄ emission suggests that CH₄ oxidation facilitated by ANME could be a promising strategy for reducing CH₄ emissions. N₂O emission was negatively linked to most bacterial and archaeal classes; however, N₂O-consuming Chloroflexi exhibited a positive correlation with N₂O emission. Additionally, a strong link between the mcrA gene in water and CH₄ production may relate to previous findings of methane production in oxygenated water. This multidisciplinary study enhances our understanding and opens avenues for further research into reducing emissions by modulating microbial communities within prawn farming systems.