Abstract

A Bacillus coagulans strain isolated from palm fruit husk was tested for abilities to hydrolyse plant structural polysaccharides through the depolymerising activities of carboxymethylcellulase and polygalacturonase. The two enzymes were produced using solid substrate fermentation. Both had a working pH range of 4 - 9 with an optimum pH of 6.0 for the carboxymethylcellulase and 7.0 for the polygalacturonase. The respective enzymes remained active when allowed to stand at 27°C for 1 h over a wide pH and temperature range maintaining maximum activity at an optimum temperature of between 50°C and 60°C respectively. The carboxymethylcellulase still retained full activity after being allowed to stand at 60°C for 10 min while the polygalacturonase retained full activity at 80°C for 5 min and had 50% activity at 70°C at 30 min. All enzymatic activities were fully inhibited by Mercury ions at 1.0 mM concentration. The carboxymethylcellulase had a molecular weight of between 116 and 205 KDa and another at 6.5 KDa. The molecular weight recorded for the polygalacturonase was 6.5 KDa. Polygalacturonase activity was enhanced by all surfactants applied while that of the cellulase was slightly enhanced by SDS and more by higher concentrations (0.5 - 5.0%) Tween-80.

Key words: Physiological study, Bacillus coagulans, carboxymethylcellulase, polygalacturonase, palm fruit husks.