Production and optimization of L-asparaginase from Cladosporium sp using agricultural residues in solid state fermentation

The present communication deals with the production of L-asparaginase from Cladosporium sp. in solid state fermentation (SSF) using agro-industrial residues. When used as sole source for growth in SSF, wheat bran supported maximum enzyme production by Cladosporium sp. followed by rice bran and bagasse. Central composite rotatable designs (CCRDs) with five process variables were studied each at levels -2, 1,0, +1 and +2. A 120h fermentation time under aerobic condition optimized using response surface methodology (RSM) indicated that with moisture content of 58%, pH of 5.8, incubation temperature of 30 degrees C appeared optimal for enzyme production by SSF. Enzyme yield (3.74 U) was maximum at these optimized conditions. Presence of Tween 20 enhanced enzyme production by 1.3 folds. A bed height of 3 and 5 cm was appropriate to obtain high enzyme production. The results optimized could be translated to 1 kg tray fermentation. The study suggested that choosing an appropriate substrate when coupled with process level optimization improves enzyme production markedly. Developing an L-asparaginase production process based on wheat bran as a substrate in SSF is economically attractive as it is a cheap and readily available raw material in agriculture-based countries. This result is of significant interest due to the low cost and abundant availability of residues. (C) 2012 Elsevier B.V. All rights reserved.