826 / 2024-09-19 14:49:19

Microbial Greenhouse Gases Metabolism Potentials in Coastal Environment: a case study of Hangzhou Bay

Microbial metabolism,greenhouse gases (GHGs),Shotgun metagenomic sequencing,effluent discharge of WWTP,Hangzhou Bay

Coastal environment plays a crucial role in maintaining the health and stability of global ecosystems. With the continuous influx of land-based materials and increasing human activities, coastal areas are facing growing pollution burdens. The pollutants not only disrupt coastal ecological balance but also affect the cycling of elements. Microorganisms, as key decomposers in ecosystems, rapidly respond to environmental changes and play a critical role in coastal carbon metabolism, greenhouse gases (GHGs) regulation and climate change. However, due to their complex diversity and varying responses to environmental pressures, the estimation of microorganisms’ contribution in GHGs metabolism is not clear.

This study took Hangzhou Bay (HB), a typical polluted coastal environment in China, as the research area. First of all, we built a GHGs gene database, which covers 82 gene families and 89,054 sequences related with the emission or adsorption of CO₂, CH₄, and N₂O. Then we collected sediment samples from 10 sites in HB and conducted shotgun metagenomic sequencing. According to the sequences’ annotation on the new GHGs gene database, we identified the potential pathways of microbial GHGs metabolism; and finally evaluated the impact of different pollution level on the GHGs metabolic changes by microbial communities. The results show that, though HB overall exhibits as a GHGs sink, the GHG fixation function of microorganisms was inhibited, especially in the habitat with high-pollution level. Further exploration of two effluent receiving areas (ERAs) of wastewater treatment plants (WWTPs) indicated increased potential for microbial GHG emissions, suggesting that WWTP discharge not only affected microbial community structures, but also drove higher microbial GHGs emissions. In addition, chemical oxygen demand (COD) of the ERAs seawater had a particularly significant impact on microbial GHG genes. These findings disclosed that the discharge of pollutants have a severe impact on microbial GHGs metabolism and interferes with their ability to absorb and fix GHGs. In other words, land-based pollution might make certain loss in the coastal environment as GHGs sink.