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SINET: Ethiopian Journal of Science

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Production and optimization of cellulase from Trichodrma isolates under liquid state fermentation (LSF)

Weldesemayat Gorems, Tesfaye Alemu

Abstract


Pure cellulose was used as sole carbon source for the production of cellulase by Trichoderma isolates under liquid state fermentation (lsf). Carboxymethyl cellulose (cmc) and Congo Red were used and considered only four Trichoderma isolates with stronger ability to produce and optimize cellulase. Cellulase production was assayed by measuring the amount of glucose liberated in μmol/ml/min by using the dinitrosalicylic acid reagent (dns) assay method at 540nm absorbance. To maximize cellulase production, the critical parameters such as carbon source, nitrogen source, cellulose concentration, cultivation temperature and pH on enzyme production were optimized using lsf. The highest cellulase activity was observed after 12 days of incubation on media containing, yeast extract (1%), cellulose concentration (1%) and pH (5.5) from seven Trichoderma isolates under lsf. Cellulase synthesis was repressed in the presence of glucose and fructose while it was induced in the presence of maltose and lactose under lsf. It is evident from the present study that the cellulase production extracted to maximum level from Trichoderma isolates was active at temperature ranges of 40–60°C and pH values 4.5–6.5. Yeast extract was the preferred nitrogen source to produce cellulase under lsf; and shaking of the culture improved cellulase production by about 2–3 factors higher than a static culture. This indicated that oxygen supply is the critical factor for the growth and enzyme production by Trichoderma isolates. Therefore, these cellulase producing Trichoderma isolates can be used in food industries, animal feed industries, brewing and wine making, agriculture biomass refining, pulp and paper industries, textile and laundry industries and ethanol production.



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