Mixing of Prosopis africana pods and corn cob exerts contrasting effects on the production and quality of Bacillus thuringiensis crude endoglucanase

Abstract

Recently, attention has shifted to the use of mixed lignocellulosic substrates for the production of cellulolytic enzymes. However, researchers have focused mainly on achieving increased enzyme yields while neglecting other properties of the enzymes when using such mixtures. In this first-ever report of the application of Prosopis africana pod (PAP) in cellulase production, we investigated the effect of its combination with corn cob (CC), as an inducing carbon source, on the amounts and quality of crude endoglucanase produced by Bacillus thuringiensis SS12. The organism was grown on PAP, CC or their 1:1% w/w mixture (MS) and the crude endoglucanases produced were tested for activity, hydrolytic efficiency, and thermostability. PAP supported the highest enzyme activity (0.138 U/mL) and its endoglucanase was the most effective in hydrolyzing CMC and filter paper while CC-derived endoglucanase was the best for hydrolysis of alkali-pretreated CC. Enzyme activity of MS-derived endoglucanase (0.110 U/mL) was intermediate to that of PAP and CC (0.091 U/mL) and was the most stable at elevated temperatures (70 and 80 °C). It also liberated the least amount of reducing sugars from all tested substrates. Combination of both the substrates, thus, favored enzyme production and thermostability but was detrimental to hydrolytic efficiency.

Keywords:

• Corn cob
• endoglucanase
• enzymatic hydrolysis
• mixed lignocellulosic biomass
• Prosopis africana pods
• thermostability

Acknowledgments

The authors thank Mr. Idris Sheriffdeen Olakunle and Mr. Oyediji Kehinde Eyitayo of the Department of Microbiology, Faculty of Life Sciences, University of Ilorin, Nigeria, for their technical support.

Disclosure statement

The authors declare no conflict of interest in this work.