Utilization of wheat straw for fungal phytase production

Younes Ghasemi,Mohammad J Taherzadeh,Zohre Shahryari,Payam Setoodeh,Ramkumar B Nair,Mohammad H Fazaelipoor

doi:10.1007/s40093-018-0220-z

Abstract

PurposeWheat straw is an agricultural waste which can be used as a cost effective animal feed. However, high hemicellulose and phytic acid content in wheat straw prevents it as a primary feed choice. Utilization of wheat straw in solid-state fermentation may result in wheat straw valorization and enzyme production. In this study, phytase production in solid-state fermentation of wheat straw using Aspergillus ficuum and valorization of wheat straw were evaluated.MethodsA two-step experimental design procedure was employed for screening and optimization of influencing factors on phytase production. Effects of different nutritional and environmental factors were investigated by one factor at the time method (OFATM). To reach higher amounts of phytase, response surface methodology (RSM) was employed to optimize phytase production as a function of three of the most effective factors.ResultsOptimization of the significant parameters resulted in an increase in the phytase activity from 0.74 ± 0.12 to a maximum of 16.46 ± 0.56 Units per gram dry substrate (U gds−1). The high degree of the fungal phytase activity on wheat straw resulted in the decrease in phytic acid content by 57.4%, as compared to the untreated sample. Scanning electron microscopy (SEM) and FTIR structural analysis showed intensive fungal growth on wheat straw, and partial removal of hemicelluloses, lignin and phytic acid.ConclusionThe study demonstrated the feasibility of wheat straw utilization in solid-state fermentation using Aspergillus ficuum toward the production of phytase and valorization of wheat straw as an animal feed.

Highlights

Wheat straw is the second most abundant lignocellulosic raw material in the world (Pensupa et al 2013)
Phytase production from wheat straw was found to improve its digestibility as observed with its structural analysis
Solid-state fermentation of wheat straw using Aspergillus ficcum is a feasible way to valorize the straw as an animal feed

Summary

Introduction

Wheat straw is the second most abundant lignocellulosic raw material in the world (Pensupa et al 2013). The international grain council forecasted the annual world wheat production of 754 million tons in 2016 (ICG 2017) with a straw to grain ratio of 1.3 (for most wheat varieties). Wheat straw is used as animal feed, as supporting materials (Panthapulakkal et al 2006), as raw material for pulp and paper production (Nasser et al 2015), and as a substrate for biogas, bioethanol, and mushroom production. Wheat straw is burnt as a fuel and is added to soil for its maintenance (Ferreira et al 2014; Huang et al 2017; Mahboubi et al 2017; Tomás-Pejó et al 2017). Wheat straw contains 350–450 g kg−1 cellulose, making it an excellent potential source of energy for ruminants.

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