Fungal community diversity and their contribution to nitrogen cycling in in-situ aerated landfills: Insights from field and laboratory studies

The application of in-situ aeration technology in landfills has been reported to promote fungal growth, but the community diversity and function of fungi in the aerated landfill system remain unknown. This study firstly investigated an in-situ aerated remediation landfill site to characterize the fungal community diversity in refuse. And to further reveal the fungal involvement in the nitrogen cycling system, laboratory-scale simulated aerated landfill reactors were then constructed. The results in the aerated landfill site showed a significant correlation between fungal community structure and ammonia nitrogen content in the refuse. Dominant fungi in the fungal community included commonly found environmental fungi such as Fusarium, Aspergillus, Gibberella, as well as unique fungi in the aerated system like Chaetomium. In the laboratory-scale aerated landfill simulation experiments, the fungal system was constructed using bacterial inhibitor, and nitrogen balance analysis confirmed the significant role of fungal nitrification in the nitrogen cycling process. When ammonia nitrogen was not readily available, fungi converted organic nitrogen to nitrate, serving as the main nitrification mechanism in the system, with a contribution rate ranging from 62.71 % to 100 % of total nitrification. However, when ammonia nitrogen was present in the system, autotrophic nitrification became the main mechanism, and the contribution of fungal nitrification to total nitrification was only 15.96 %. Additionally, fungi were capable of directly utilizing nitrite for nitrate production with a rate of 4.65 mg L−1 d−1. This research article contributes to the understanding of the importance of fungi in the aerated landfill systems, filling a gap in knowledge.