A newly isolated lignin degradation bacterium Acinetobacter sp. B213 pretreatment effectively improved hydrolysis of corn straw by enhance cellulose retention and reduce lignin degradation inhibitor

Abstract An improvement of lignin depolymerization while reducing cellulose losses during the pretreatment by microorganisms gains an interest in the highly efficient utilization of lignocellulosic biomass. Here, a strain isolated from activated sludge could utilize lignin as the sole carbon source and identify as Acinetobacter sp. B213. By measuring the growth curve, degradation characteristic and lignolytic enzymes activity of Acinetobacter sp. B213, the culture medium and inoculum size were optimized. The optimal medium was sodium lignosulfonate LB medium and the optimal inoculum size was 8%. After the biological pretreatment of corn straw under the optimized conditions, the cellulose retention rate and lignin degradation rate were 98.51% and 12.02%, respectively. Approximately 10.53% increase in cellulose retention rate and 20.36% decrease in lignin degradation rate was observed compared with the chemical pretreatment (87.98% and 32.38%), respectively. After 24 h hydrolysis, the glucose yield of biological pretreatment corn straw was 100%, which was 14.25% higher than that of the chemical pretreatment. These results indicated that the biological pretreatment with selective lignin degradation has an advantage in the hydrolysis of cellulose and produces glucose, although the lignin degradation efficiency was lower than chemical pretreatment.