Exposure to para-chloro-meta-xylenol enhances N2O emission by altering key genes involved in nitrogen cycling processes and the microbial community in sediment

An increase in para-chloro-meta-xylenol (PCMX) pollution presents a significant obstacle to ecological security. The present study employed a series of microcosmic experiments to investigate the temporal dynamics of N2O emissions and key genes involved in nitrogen cycle during the biodegradation process of PCMX. The results demonstrated that the degradation of PCMX exhibited first-order kinetics, with a calculated half-life of 231 days. The quantitative PCR results indicated that PCMX inhibited the ammonia oxidation gene (amoA), N2O reduction gene (nosZ) and of hydrazine synthase (hzsB), but stimulated the key genes for denitrification (narG and norB) growth, which led to increased emission of N2O by 1.73 times in 90 days. The co-occurrence network analysis indicated the reconstruction of more intricate yet weaker interrelationships, revealing that Proteobacteria and Firmicutes, rather than Acidobacteriota, established close associations with other microorganisms in response to PCMX exposure. These findings clearly elucidate the effects of PCMX on N2O emissions and the microbial community in sediment.