Synergistic treatment of crude enzymes from Bacillus sp. strains to boost anaerobic fermentation of rice straw

Waste carbon straw like rice straw (RS) could be consumed as an ideal substrate in anaerobic fermentation for biofuel production. However, this practice is obstructed by the existence of the lignin polymer in RS. Enzyme lysates from individual strains and enzyme lysate mixture from all seven strains were used in to remove the lignin of waste carbon straw (RS). The effect of enzyme lysate on removing lignin and increasing fermentation rate was measured. Maximum delignification of RS was obtained from enzyme mixture of all seven bacterial strain crude samples as compared to individual enzyme lysates of these bacterial strains. A selective lignin reduction of 46.7% was obtained from enzyme mixture-pretreated RS samples; however, the highest individual TL26E enzyme lysate degrades 19.9% of the lignin from the treated RS sample. Scanning electron microscopy (SEM) analysis displayed a visible modification in the organic fiber of the pretreated RS samples compared to the untreated RS. The cumulative biogas was up to 260–280 NmL/gVS from the individual enzyme lysate. However, maximum cumulative biogas of 489.6 NmL/gVS was obtained from enzyme mixture-pretreated RS. Cumulative biogas produced from treated RS was 38% higher than the untreated RS. The study suggests that the synergistic enzymatic treatment could be more effective for waste biomass hydrolysis in bioprocess technology.