Insight into the microbial community of denitrification process using different solid carbon sources: Not only...

Area of Science:

• Environmental Microbiology
• Water Treatment Technologies
• Biotechnology

Background:

• Solid-phase denitrification (SPD) systems are crucial for removing nitrate from wastewater.
• The microbial communities driving SPD processes, including bacteria, fungi, and archaea, are not fully understood.
• Different carbon sources can significantly influence the efficiency and microbial composition of SPD systems.

Purpose of the Study:

• To investigate the impact of various carbon sources on the microbial community composition and denitrification efficiency in SPD systems.
• To compare the effectiveness of operational taxonomic unit (OTU) and amplicon sequence variant (ASV) methods for analyzing SPD microbial communities.
• To explore potential collaborations between microbial taxa and their functional roles in SPD.

Main Methods:

• Four SPD systems utilizing different carbon sources (corncob-polyvinyl alcohol sodium alginate-polycaprolactone, corncob, polycaprolactone, polyvinyl alcohol-sodium alginate) were established.
• Microbial gene sequences were analyzed using both OTU and ASV approaches.
• Denitrification efficiency was quantified by measuring nitrate-nitrogen removal rates.
• Bioinformatic analyses included microbial community composition, diversity, co-occurrence network analysis, and KEGG functional prediction.

Main Results:

• Corncob and CPSP demonstrated significantly higher denitrification efficiencies (0.85-0.86 mg NO3--N/(g·day)) compared to PCL and PVA-SA (0.24-0.29 mg NO3--N/(g·day)).
• Distinct microbial compositions were observed across different carbon sources, with notable differences in dominant phyla like Proteobacteria and Rozellomycota.
• The ASV method identified a greater number of microbial units and higher alpha diversity than the OTU method, revealing previously unclassified taxa.
• Co-occurrence networks suggested synergistic interactions among bacterial, fungal, and archaeal species.

Conclusions:

• Corncob-derived materials are superior carbon sources for enhancing denitrification efficiency in SPD systems.
• The ASV sequencing approach provides a more detailed and accurate characterization of SPD microbial communities than OTU analysis.
• Fungal and archaeal contributions to the functional capacity of SPD systems should be considered in future research and application.