Cellulases are one of the most essential natural factors for cellulose degradation and, thus, have attracted significant interest for various applications. In this study, a cellulase from Paenibacillus elgii TKU051 was produced, purified, and characterized. The ideal fermentation conditions for cellulase productivity were 2% carboxymethyl cellulose (CMC) as the growth substrate, pH = 8, temperature of 31 °C, and 4 days of culturing. Accordingly, a 45 kDa cellulase (PeCel) was successfully purified in a single step using a High Q column with a recovery yield of 35% and purification of 42.2-fold. PeCel has an optimal activity at pH 6 and a temperature of 60 °C. The activity of cellulase was significantly inhibited by Cu2+ and enhanced by Mn2+. The PeCel-catalyzed products of the CMC hydrolysis were analyzed by high-performance liquid chromatography, which revealed chitobiose and chitotriose as the major products. Finally, the clarity of apple juice was enhanced when treated with PeCel.
