Evaluation ofChlorella Vulgarisas a Source of Fermentable Sugar using Amylase ProducingBacillus Cereus

Abstract

Bacillus cereus that was previously isolated from the soil and screened for alpha-amylase production was used for hydrolysis of Chlorella vulgaris starch content. The Dinitrosalicylic acid method was used to determine the amount of reducing sugar produced. Maximum reducing sugar yield of 2.10 mg/ml was obtained for pre-treated C. vulgaris biomass, 2.06 mg/ml for untreated biomass and 2.56 mg/ml for corn starch (control) after 24 hours incubation. When the production parameters where optimized, maximum reducing sugar yield was obtained at a pH of 6.5, temperature of 35°C, incubation time of 24 hours and 4% inoculums concentration for pretreated C. vulgaris biomass. Also, a 1.3 fold reducing sugar yield was enhanced when compared with non-optimized conditions indicating the usefulness of optimization on biochemical processes. The maximum reducing sugar obtained for hydrolysis of pretreated C. vulgaris biomass is similar to the reducing sugar yield of corn starch. Also, the carbohydrate content of C. vulgaris hydrolysis was 66% which is comparable to the carbohydrate content of corn (about 73%). This indicates the potential of C. vulgaris as an alternative substrate for fermentable sugar production.