초록
To understand the enzymological basis for extremely thermophilic, biomass-degrading genus Caldicellulosiruptor metabolize pectin, a thermostable pectate lyase Pel-863 encoded by a gene cluster for hexose-containing polysaccharide metabolism in genome of C. kronotskyensis was studied. The pectate lyase of Caldicellulosiruptor was highly conserved and the representative Pel-863 was biochemically characterized, and the application for pectin containing biomass degradation was also studied. Pel-863 exhibited an optimal activity at 70<SUP>o</SUP>C and pH 9.0 with Ca<SUP>2+</SUP> as cofactor. It degraded polygalacturonic acid (PGA), methylated pectin and pectic biomass through endo-cleaving action. The respective V<SUB>max</SUB> and K<SUB>m</SUB> for Pel-863 were 172.8U/mg and 0.60g/L on PGA. FTIR and SEM analysis indicated that Pel-863 could remove most of pectin in hemp fiber with less damage compared to alkaline degumming. In addition, pre-digestion with Pel-863 improved glucose and xylose yield by 14.2% and 311.6% respectively for corn stalk, 6.5% and 55% for rice stalk compared with sole action of Novozymes Cellic CTec2.