文摘
We previously reported on a new yeast strain of Clavispora sp. NRRL Y-50464 that is capable of utilizing cellobiose as sole source of carbon and energy by producing sufficient native 尾-glucosidase enzyme activity without further enzyme supplementation for cellulosic ethanol production using simultaneous saccharification and fermentation. Eliminating the addition of external 尾-glucosidase reduces the cost of cellulosic ethanol production. In this study, we present results on the isolation and identification of a 尾-glucosidase protein from strain Y-50464. Using Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and blast search of the NCBInr database (National Center for Biotechnology Information nonredundant), the protein from Y-50464 was identified as a 尾-glucosidase (BGL1) with a molecular weight of 93.3聽kDa. The BGL1 protein was purified through multiple chromatographic steps to a 26-fold purity (K m鈥?鈥?.355聽mM [pNPG]; K i鈥?鈥?5.2聽mM [glucose]), which has a specific activity of 18.4聽U/mg of protein with an optimal performance temperature at 45聽掳C and pH of 6.0. This protein appears to be intracellular although other forms of the enzyme may exist. The fast growth rate of Y-50464 and its capability to produce sufficient 尾-glucosidase activity for ethanol conversion from cellobiose provide a promising means for low-cost cellulosic ethanol production through a consolidated bioprocessing development.