Fig. 2
Plots of average methane production from coal bioconversion after the 28-day cultivation using coal and grassland soil microbial inoculums. Basal anaerobic medium was used for methanogenic coal bioconversion. Soil samples (0.5 g) and/or coal powder (0.3 g) were placed in 30 mL autoclaved anaerobic medium and incubated at 30 °C. Error bars represent standard deviation for replicates tubes. Soil (S) represents sterile soil; coal (S) represents sterile coal. Coal and soil represent the original coal and soil samples, respectively