Gel Foam Loaded O₂-Consuming Microbial Community and the Stratification Structure in Preventing Coal Spontaneous Combustion

Gel foam is vital to its applications but remains a challenge. Herein, microbial gel foam was developed for coal spontaneous combustion, which was a gel foam loaded O₂-consuming microbial community. The microbial gel foam had the ability to consume O₂ and produce CO₂. The O₂ consumption was 94.46%, and the percentage of CO₂ reached 48.88% at 250 h. The relative abundance of <i>Enterobacteriaceae</i> and <i>Candida</i> was 93-98% and 73-77% in the upper gel foam and the bottom liquid of microbial gel foam at 240 h, respectively. Fungal in the O₂-consuming microbial community has stronger environmental tolerance than the bacterial, which was more suitable for loading in gel foam. Although the gel foam would collapse and deform, some flagellated microorganisms in the gel foam sealed the pores caused by the collapse of the foam. The "inert gas-foam layer" was formed by microorganisms at the junction of the foam and bottom liquid, which was conducive to the oxygen isolation function of the gel foam. Our results could be helpful in understanding the spatial structure of microbial gel foam and developing microbial gel foam with strong O₂ consumption.