Production of Thermostable β-Mannanase from Aspergillus niger using Submerged Fermentation

Mannanases are one of the important lignocellulose degrading enzymes having potential biotechnological applications in a wide range of industries, including detergent industry, food and feed technology, coffee extraction, bioethanol production, pharmaceutical field, pulp and paper industry. The present study deals with the β-mannanase producing fungi. Fungal Strain Aspergillus niger was isolated from compost soil samples collected from Indore region and it was found to produce a significant amount of β-mannanase on solid agar plate and liquid media. Optimization was carried out for various physico-chemical parameters for maximum production of mannanase. After standardization we found that Aspergillus niger gave maximum production of mannanase (21U/ml) on the 10th day of incubation. Among different carbon and nitrogen sources 1% LBG and 0.5% yeast extract shows maximum enzyme production i.e. 21 U/ml and 39.89 U/ml respectively. The best temperature and pH for maximum yield of mannanase were 37oC (21.34 U/ml) and pH 6.0 (26.46 U/ml). The optimum inoculum size was found to be 107 spores/ml, giving maximum mannanase yield up to 22.63 U/ml. Mannanase was partially purified using ammonium sulfate fractionation and desalting using G25 column. The partially purified mannanase had optimum pH and temperature for activity at 3.8 and 75oC respectively and was found stable at 3-7 pH and 40-70oC temperature range.