The inhibition of cystathionine gamma-lyase and cystathionine beta-synthase - a strategy to reduce hydrogen sulfide emissions during livestock manure composting.

The composting of livestock manure produces a significant amount of hydrogen sulfide (H2S), which can cause environmental pollution. This has become a substantial impediment to the advancement of the composting industry. In this study, Cystathionine gamma-lyase (CSE) and Cystathionine beta-synthase (CBS) enzymes were explored from the perspective of endogenous H2S production. This study investigated aminooxyacetic acid (AOAA) and DL-propargylglycine (PAG) as enzyme inhibitors in composting to assess the feasibility and effectiveness of H2S emission reduction from chicken and swine manure. The results showed that the treatment groups reduced the cumulative H2S emissions by a minimum of 33.52% and a maximum of 72.11%. The CSE and CBS-mediated H2S production reaction was inhibited by AOAA and PAG, which resulted in a significant reduction (P < 0.05) in H2S emission during composting and a considerable decrease in the loss of sulfur components in gaseous form. Furthermore, the addition of AOAA and PAG affected the genes related to organic sulfur metabolism and the sulfur metabolism cycle network. This study is the first to investigate the addition of two enzyme inhibitors in composting, examining the mechanisms at different levels. These results provide new insights into the compost management strategies for the reduction of H2S emissions. This is a crucial area of research for the reduction of environmental pollution and the advancement of the composting industry.