Isolation and identification of thermophilic cellulolytic yeast from cassava waste dump

Abstract

Cellulase is an enzyme complex which breaks down cellulose to glucose. The need for economical, complete and fast industrial processes necessitates the use of very active starters able to operate at high temperature of production to degrade cheap nutrients most of which are cellulolytic; hence the search for thermophilic cellulolytic yeasts from the environment. Isolation and identification of thermophilic yeasts were made from the soil samples using standard procedures and obtained isolates were screened for cellulolytic enzymes production. The enzymes were characterised using different parameters such as temperature, pH, substrate concentrations, enzyme concentrations and metal ion concentrations. A total of seven thermophilic yeasts were isolated from cassava waste dump sites and identified as Torulopis sphaerica, Kloeckera apiculata, Pichia canadensis, Pichia species, Candida krusei, Candida utilis and Rodotorula rubra. They all had optimum growth at temperature and pH of 55ºC and 6.0 respectively. The optimum temperature and pH for cellulolytic activities ranged from 45-55ºC and 5-6 respectively. Cellulolytic activities increased with increase in the concentration of substrate, enzymes and metal ions.