Microbial degradation behaviour and interactions in efficient multi-compound VOCs removal

Biodegradation efficiency of volatile organic compounds (VOCs) hinges primarily on microbial activity. In particular, extensive interaction behavior occurs among microbial species and VOCs-degrading microbial communities during the removal of multi-component VOCs. In this study, methyl mercaptan, dichloromethane, n-hexane and toluene were selected as representative VOCs, corresponding to sulfur-containing pollutants, chlorinated organics, alkanes and aromatics commonly found in multi-component waste gas from pharmaceutical and fine chemical industries. Suspension-cultured strains of Pseudomonas sp. SJ-1, Methylobacterium rhodesianum H13, Stenotrophomonas sp. HY-2, and Ralstonia sp. XZW-1 were used were selected as corresponding functional degraders. Reduction of VOCs in the headspace and increase of OD₆₀₀ in liquid medium across the 15 groups indicate nontarget VOCs promote SJ-1 and XZW-1 yet suppress H13 with little influence on HY-2; XZW-1 synergizes with all strains, H13 competes broadly, and SJ-1 cooperates with HY-2. The determination of dehydrogenases and end products of CO₂, SO₄^2-, and Cl^- also confirmed the results, and the metabolic pathways of four VOCs under mixed conditions of four strains were further hypothesized through the detection of some intermediate products. Additionally, to improve dichloromethane and n-hexane elimination, the four-strain consortium was proportioned at 1:2:1:1 and immobilized on bagasse-activated carbon-sawdust via solid fermentation and found that the culture maintained long-term viability at 30 °C (optimal), benefiting complex VOCs removal. It is believed that this study provides key data for practical mixed-VOC biotreatment and is expected to advance industrial application of biodegradation.