Cultural Conditions Necessary for Optimal Cellulase Yield by Cellulolytic Bacterial Organisms as They Relate to Residual Sugars Released in Broth Medium

A total of 115 samples made up of 42 (36.5%) rumen fluid, 36 (31.3%) cowdung and 37 (32.2%) soil samples were collected with the aid of sterile swab sticks except for rumen fluid samples which were collected by use of stomach tubes inserted into mouths of cows and by suction, liquor was collected into prewarmed thermo flasks under continuous flushing with carbondioxide. Soil samples were collected into sterile universal containers. All samples were obtained from abattoirs situated at three locations in Benin City, Nigeria. Samples were investigated for cellulolytic bacteria by Filter Paper Yeast Mineral broth method. Cellulase production was assayed by Carboxymethyl cellulose submerged broth culture while residual sugar yield and other cellulolytic activities were determined by 3, 5 – Dinitrosalicylic acid, Filter Paper, Microcrystalline and Viscometric methods. Cellullolytic bacterial organisms isolated from both soil and rumen fluids were Bacillus subtilis, Clostridium cellobioparum and Clostridium thermocellum. Pseudomonas aeruginosa was isolated from both soil and cowdung samples while Erwinia spp was obtained from both rumen fluid and cowdung samples. Bacillus circulans and Serratia spp were obtained from soil samples only. Clostridium thermocellum and Erwinia spp produced the highest and lowest cellulase yields respectively. All isolates at 40oC and pH 6, recorded optimal sugar yields in culture broth of which Clostridium thermocellum recorded the highest. Lowest yields were recorded at 30oC and pH 3 although there was significant difference in individual yields (P < 0.05). Clostridium thermocellum recorded optimal cellulolytic activities at 50oC and pH 6. All isolates attained optimal cellulolytic activities at 32.6 ± 6.2oC and pH 6.29 ± 0.9 with other broth cultural conditions kept constant. Implications of these findings are discussed.