Bioprocessing of Agricultural Wastes as Optimised Carbon Source and Optimisation of Growth Conditions for Xylanase Production by Aspergillus brasiliensis in Agitated Solid State Fermentation (Ssf)

Hooi Ling Ho Lee Yong Lau

doi:10.4172/2376-0214.1000125

Abstract

Objective: Xylanase has been involved in many industrial applications especially in the pulp and paper, baking, detergent as well as food and beverage industries. This enzyme is produced by various microorganisms, mainly from fungal species. Therefore, in this study, Aspergillus brasiliensis ATCC 16404 was investigated for the optimum xylanase production under agitated solid state fermentation (SsF) using different agricultural wastes as alternative inexpensive carbon source. Methods: A. brasiliensis was cultured in 10 g agricultural waste with addition of 2% yeast extract as the nitrogen source up to 120 h of SsF to elucidate xylanase production. Effect of various agricultural wastes such as wheat bran, rice bran, soybean hulls, barley husk, maize and palm kernel cake (PKC) on xylanase activity were enumerated in a stepwise manner, where one parameter was investigated at a time approach to obtain the optimum carbon source for the maximum xylanase production by A. brasiliensis. Thereafter, growth temperatures from 25 to 45°C, initial medium pH from 4 to 10 and agitation speeds of 50 to 200 rpm were also elucidated to determine the optimum growth conditions for the maximum production of xylanase by A. brasiliensis. Results: Based on our results, the highest xylanase activity of 7.30 ± 1.93 U/mL was obtained using wheat bran as the prime carbon source with the initial medium pH 6.5 at 30°C at the agitation speed of 150 rpm. Conclusion: Thus, in our study, the maximum xylanase production by A. brasiliensis using solid state bioprocessing of wheat bran as the carbon source was achieved with the addition of 2% yeast extract as the nitrogen source under the optimum growth conditions of 30°C with medium pH 6.5 at 150 rpm.

Highlights

Xylanase is an inducible enzyme which is responsible for the complete hydrolysis of xylan into simpler compounds which are mainly consisted of xylose [1]
A study conducted by Kavya and Padmavathi [20] which reported that wheat bran showed the highest xylanase activity of 9.87 U/mL in solid state fermentation (SsF) by A. brasiliensis that was isolated from the mixed soil sample
Wheat bran contains high concentration of protein, which is more than 14%, while other agricultural wastes such as corn cobs consists of only 2.0% [15]

Summary

Introduction

Xylanase is an inducible enzyme which is responsible for the complete hydrolysis of xylan into simpler compounds which are mainly consisted of xylose [1]. The addition of xylanase in animals feed helps to degrade arabinoxylans which are the major components of the hemicellulosic complex found in plant cell wall. As a result, it fastens digestion of the animals feed to improve the nutrients absorption whereby the nutrients that trapped within the cell wall would release and absorb with the present of xylanase. Xylanase improves the elasticity of gluten and structure of bread crumb and increases the volume of bread As a result, it enhances the overall quality of bread. In brewing industry, the problem of viscous polysaccharides such as xylan in the final beer filtration process is overcome with the pre-treatment of using xylanase to break down the xylan and increases the rates of filtration and prevents the accumulation of unwanted materials during brewing process [6]

Methods

Results

Conclusion