Optimisation of Medium Formulation and Growth Conditions for Xylanase Production by Aspergillus brasiliensis in Submerged Fermentation (SmF)

Hooi Ling Ho Jamila Said Hood

doi:10.4172/2376-0214.1000102

Abstract

Objective: There has been much concern and immense importance on xylanase due to its potential industrial applications in the manufacturing of pulp and paper, baking, food and beverages, textile and animal feeds production. There are continuously endeavors to turn xylanase into a profitable market with lower production costs using optimum fermentation medium and growth conditions. Thus, the main objectives of this study were to determine the optimum medium formulation and growth conditions for the production of xylanase by Aspergillus brasiliensis ATCC 16404 and to elucidate the correlation of xylanase synthesis with biomass, pH and protein concentration in submerged fermentation (SmF). Methods: The effect of various carbon sources: sucrose, glucose, maltose, galactose, glycerol, lactose and ethanol and nitrogen sources: yeast extract, urea, peptone, ammonium sulphate, ammonium nitrate, ammonium chloride and sodium nitrate on xylanase activity were examined to obtain the optimum medium formulation for xylanase activity by A. brasiliensis. In addition, growth temperatures of 28 to 36oC and initial pH medium of 3 to 11 were also examined to elucidate the optimum growth conditions for the production of xylanase. Results: The highest xylanase activity of 39.567 U/mL at 72 h was obtained using sucrose and yeast extract as the optimised carbon and nitrogen sources. Our results also showed that 30°C and pH 6.5 were the optimum growth condition of A. brasiliensis for xylanase synthesis. 38.528 U/mL of xylanase activity was observed at 72 h when the initial pH medium was adjusted to 5.0. Nevertheless, when the initial pH medium was increased to 6.5, the xylanase synthesis increased almost 3% at 72 h. Conclusion: Hence, in our study, the optimum medium formulation and growth conditions for the production of xylanase by A. brasiliensis in SmF was achieved by growing the fungi in medium containing sucrose and yeast extract with the initial medium pH 6.5 at 30°C.

Highlights

In recent years, considerable attention has been paid to the use of microorganisms in industrial fermentation processes, especially enzyme production
The addition of carbon and nitrogen sources is a general practice to improve the nutritional requirement for the growth and production of xylanase by A. brasiliensis
Xylanase synthesis by A. brasiliensis was highly affected by the growth conditions including growth temperature and pH medium

Summary

Introduction

Considerable attention has been paid to the use of microorganisms in industrial fermentation processes, especially enzyme production. Several reports were studied on microorganisms producing xylanase in nature and these include yeast, bacteria and fungi [2]. Filamentous fungi, such as Aspergillus [3], Penicillium and Trichoderma [4,5] have been most extensively studied. They have established a great capability of producing a wide range of xylanase where Aspergillus spp remains the fungi of choice for production of xylanase [6]. Xylanase production yield from fungi culture is apparently higher as compared to that of yeast and bacteria cultures. The production of microbial xylanase is preferred over plant and animal sources because of their availability, structural stability and genetic manipulation [7]

Methods

Results

Conclusion