Chemical parameter optimization of feather protein hydrolysate production by Aspergillus terreus UniMAP AA-1 using submerged fermentation

Abstract

Feathers are by-product waste of poultry processing plant and in this research the protein hydrolysate production was investigated. Culture medium for protein hydrolysate production from feather by Aspergillus terreus UniMAP AA-1 was optimised. Effect of culture conditions on protein hydrolysate were tested and optimal results were obtained with a culture volume of 100 mL, culture pH value was 7.5, culture temperature was 35 °C and inoculums size of spore suspension was 2.5x108. To improve protein hydrolysate yield, statistically based experimental designs were applied to optimize the culture medium. 2-level factorial design experiments showed that from three parameters involved which was feather concentration, concentration yeast extract and concentration of K2HPO4, only feather concentration and concentration of K2HPO4 were the most significant factors affecting protein hydrolysate production. Furthermore, central composite design experiments indicated that the optimal feather concentration and concentration of K2HPO4 were 1.75 mg/mL and 0.1 mg/mL. In order to obtain the optimal protein hydrolysate concentration at 0.669 mg/mL, optimised fermentation mediums (mg/mL) such as KH2PO4 concentration, MgSO4 concentration and NaCl concentration were used at value of 0.8 mg/mL, 0.2 mg/mL and 1.0 mg/mL. Feather was degraded during submerged cultivating. The keratinous waste can be biologically degraded by enzymes or the microbe itself to form useful products.