Mutagenesis of Cellulomonas biazotea for enhanced production of xylanases

Abstract

A rifampin-resistant mutant of Cellulomonas biazotea, designated 7 Rf, secreted elevated levels of xylanases in vivo. The xylanase and β-xylosidase production in the mutant was not inhibited in the presence of 5% glucose, cellobiose or glycerol in the solid medium. This mutant showed approximately 2–3-fold enhanced product yield and productivity of cellular β-xylosidase over the wild type parent in shake flask culture studies when grown on either cellobiose, cellulosic or lignocellulosic (LC) substrates. Extracellular production of xylanase was also significantly ( P ≤ 0.05) altered in the mutant. During growth of C. biazotea mutant derivative on xylan, maximum volumetric productivities ( Q p) for xylanase and β-xylosidase were 493, and 30.7 IU/l/h, which were 1.21- and 2.29-fold improved over their respective values from the parental strain. The above values are statistically ( P ≤ 0.05) higher than the values reported in some other xylanolytic mutant organisms.