Using the sulfide-oxidizing bacterium Geobacillus thermodenitrificans to restrict H₂S release during chicken manure composting

Hydrogen sulfide (H₂S) is a toxic gas massively released during chicken manure composting. Diminishing its release requires efficient and low cost methods. In recent years, heterotrophic bacteria capable of rapid H₂S oxidation have been discovered but their applications in environmental improvement are rarely reported. Herein, we investigated H₂S oxidation activity of a heterotrophic thermophilic bacterium Geobacillus thermodenitrificans DSM465, which contains a H₂S oxidation pathway composed by sulfide:quinone oxidoreductase (SQR) and persulfide dioxygenase (PDO). This strain rapidly oxidized H₂S to sulfane sulfur and thiosulfate. The oxidation rate reached 5.73 μmol min^-1·g^-1 of cell dry weight. We used G. thermodenitrificans DSM465 to restrict H₂S release during chicken manure composting. The H₂S emission during composting process reduced by 27.5% and sulfate content in the final compost increased by 34.4%. In addition, this strain prolonged the high temperature phase by 7 days. Thus, using G. thermodenitrificans DSM465 to control H₂S release was an efficient and economic method. This study provided a new strategy for making waste composting environmental friendly and shed light on perspective applications of heterotrophic H₂S oxidation bacteria in environmental improvements.