THE ROLE OF BACILLUS SPECIES IN THE FERMENTATION OF CASSAVA

Cassava dough inoculum is added to grated cassava in order to achieve a modification of texture during fermentation into the fermented cassa va meal, agbelima. The microflora of two different types of inocula an d subsequently inoculated cassava mash at 0, 24 and 48 h of fermentati on were examined in order to determine the mechanism responsible for t he breakdown of cassava tissue. Bacillus spp. occurred in high numbers , 10(7)-10(8) cfu g(-1), in both types of inocula and persisted throug hout the cassava dough fermentation. Bacillus spp. found were B. subti lis, B. mycoides, B. pumilus, B. cereus, B. amyloliquefaciens and B. l icheniformis, with B. subtilis accounting for more than half of Bacill us isolates. All Bacillus isolates produced a wide spectrum of enzymes and showed similar enzymatic activities but only B. pumilus, B. liche niformis and B, amyloliquefaciens produced linamarase. Some isolates p roduced the tissue degrading enzymes polygalacturonase and pectin este rase and nearly all isolates hydrolysed starch. All isolates showed ce llulase activity and were able to disintegrate cassava tissue. When ca ssava pieces were incubated in amylase, cellulase, pectin esterase and polygalacturonase solutions, only pieces in cellulase solution were d issolved revealing that the breakdown of cassava dough texture during fermentation with the inocula examined is brought about by Bacillus sp p. through cellulase activity.