Suppression effects of commercial microbial materials including phototrophicpurple bacteria on methane production in submerged soil

摘要

In the present study, the effects of microbial material solution (MMS) including phototrophic purple bacteria(PPB) on methane( CH4) production from submerged soil were investigated. Seven treatments were set up: sterilizedor un-sterilized MMS was added to paddy soil with and without rice straw which were also sterilized or unsterilizedand then they were incubated at 30℃ for 4 weeks after submergence in the tube. CH4 and carbon dioxide(CO2) production were significantly higher in the treatment with unsterilized soil added with rice straw comparedto treatment with sterilized soil added with rice straw and treatment without rice straw. In the 2 treatments withunsterilized soil added with rice straw, the treatment with unsterilized MMS was significantly lower methane emissionand was detected higher PPB compared to the treatment with sterilized MMS. The accumulation of organicacids in both standing water and soil was little in the treatment where CH4 and CO2 emission were higher and thetreatment without rice straw. In contrast, the accumulation of organic acids increased in the treatment with sterilizedsoil added rice straw. These results implied the possibility that the CH4 emission which resulted from decompositionof rice straw via organic acids under submerged soil was mitigated when MMS including PPB was added,probably due to competition between methanogens and PPB for organic acids as substrates.