Screening and Identification of SOB and Its Effect on the Reduction in H2S in Dairy Farms

The problem of the foul odor caused by H2S in livestock farms has become a major complaints. In this study, optimal sulfur-oxidizing bacteria (SOB) strains were screened from dairy farm wastewater and the adjacent soil for odor treatment. The strains and physiological functions were determined by identification and genome comparison, and the optimal operating conditions were determined by experiments under different conditions. The identification results showed that the strain that had the highest homology with Halomonas mongoliensis was Halomonas sp. AEB2. The comparative genomic results showed that the average nucleotide identity and DNA–DNA hybridization value were 95.8% and 68.6%, respectively. The optimization results were as follows: sodium succinate-carbon (10 g/L) and ammonium chloride-nitrogen (0.07 g/L). The optimal operating conditions were as follows: seeding rate 4%, temperature 30 °C, stirring speed 90 rpm, and pH 8. The oxidation products of AEB2 were mainly elemental sulfur and tetrathionate, and the metabolic pathway of AEB2 was constructed accordingly. This study suggests a feasible path to reduce H2S emissions from dairy farms, and it provides theoretical support for the restoration of livestock environment and sustainability.