Lytic polysaccharide monooxygenase of soil actinomycete with potential use for lignocellulose biodegradation

ABSTRACT

Aims@#Lytic polysaccharide monooxygenase (LPMO) is an enzyme capable of cleaving glycoside bonds of recalcitrant polysaccharides through an oxidative mechanism. LPMO activity, in synergy with hydrolytic enzymes, increases the production of monomer sugars from the biodegradation of lignocellulose. This study was aimed at evaluating actinomycete S2 strain LPMO activity based on the release of xylose as one of reducing sugar and hydrogen peroxide (H2O2) in the course of lignocellulosic biodegradation. @*Methodology and results@#The oxidation activity of LPMO from actinomycete S2 strain was measured by using the substrate of Avicel supplemented with ascorbic acid and copper ions (Cu2+) to identify its effect on the release of xylose as one of reducing sugar. The optimum incubation time for the LPMO production was also conducted. Further, H2O2 quantitative analysis was performed as by-product of LPMO activity and 16S rRNA gene sequence of actinomycete S2 strain were subsequently determined. We found that supplementation of 1 mM ascorbic acid and 0.2 mM Cu2+ increased xylose as one of reducing sugar production by up to 5-fold from 255.03 to 1290 μg/mL after an optimal incubation period of 6 days. Based on H2O2 production, the LPMO activity of actinomycete S2 strain was 0.019 ± 0.001 U/mL. There is likelihood that LPMO activity derived from actinomycete S2 strain has a synergistic effect with the activity of other lignocellulose-degrading enzymes. This actinomycete showed 99% similarity to the 16S rRNA gene sequence of Streptomyces avermitilis strain EAAG80. @*Conclusion, significance, and impact of study@#LPMO enzyme activity from actinomycete S2 strain as determined by the production of reducing sugar and H2O2 was greatly increased by supplementation with ascorbic acid as an electron donor and Cu2+ ions. To the best of our knowledge, this is the first elucidation of LPMO activity from an indigenous Indonesian actinomycete.