CARBOXYMETHYL CELLULASE FROM BACILLUS SP.: ISOLATION, MACROMOLECULAR ORGANIZATION, AND CELLULAR LOCATION

Abstract

A Bacillus sp. strain isolated from termite (Odontotermes obesus) mount soils was found to produce extracellular carboxymethyl cellulase (CMCase). For further characterization the enzyme was isolated and purified from the culture supernatant. It revealed a molecular weight around 250kDa and a tetrameric structure, with a molecular weight of the subunits around 62kDa. Only one type of subunit was found. The enzyme was active over a wide range of conditions (30°C to 65°C; pH 3.0 to pH 11.0). Highest enzyme activity was measured at 50°C and a pH of 6.0. The enzyme was found to be not glycosylated. Glucose and cellobiose, the low molecular weight degradation products produced by the enzyme, did not induce or repress enzyme synthesis. A polyclonal antiserum was raised against the purified enzyme and applied for studies on the cellular location of the enzyme prior to secretion into the culture medium. The enzyme was shown to be located within the cytoplasm and at the cell periphery.