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Cost-effective saccharification of cellulose and hemicelluloses to fermentable sugars is of critical importance to bioconversion of lignocellulosic feedstocks to biofuel. Therefore, it is expedient to investigate the roles of medium components in optimizing lignocellulose biodegradation process. In this study, corn cob was exposed to degradation by Sporothrix carnis CPF-05 under submerged fermentation. Influence of amino acids and metal ions on biodegradation efficiency, yield of fermentable sugars and activities of degrading enzymes was investigated. It is highly remarkable that degradation of lignocellulosic biomass by S. carnis CPF-05 improved in the presence of tyrosine, glutamic acid, aspartic acid, Mn2+ and Cu2+ with biodegradation efficiency in the range of 116% to 132% compared with control. Impressive yield of glucose and xylose of about 3.0 fold increase over control was obtained in media supplemented with polar amino acids with improved production of hydrolytic and oxidative enzymes (215% - 281% relative activities). Mn2+ and Cu2+ enhanced 3.5 and 3.0 fold increase in yield of glucose and xylose, respectively. Decrease in biodegradation efficiency was recorded in the presence of non-polar amino acids (leucine, tryptophan and valine), Zn2+ and Fe2+. Results revealed that polar amino acids serve as alternatives to complex nitrogenous substrates in enhancing lignocellulose biodegradation.
Keywords: Amino acids; biodegradation; lignocellulose; metal ions; Sporothrix carnis