Kinetics of Bioethanol Production from Waste Sorghum Leaves Using Saccharomyces cerevisiae BY4743

Daneal Rorke,Evariste Gueguim Kana

doi:10.3390/fermentation3020019

Abstract

Kinetic models for bioethanol production from waste sorghum leaves by Saccharomyces cerevisiae BY4743 are presented. Fermentation processes were carried out at varied initial glucose concentrations (12.5–30.0 g/L). Experimental data on cell growth and substrate utilisation fit the Monod kinetic model with a coefficient of determination (R2) of 0.95. A maximum specific growth rate (μmax) and Monod constant (KS) of 0.176 h−1 and 10.11 g/L, respectively, were obtained. The bioethanol production data fit the modified Gompertz model with an R2 value of 0.98. A maximum bioethanol production rate (rp,m) of 0.52 g/L/h, maximum potential bioethanol concentration (Pm) of 17.15 g/L, and a bioethanol production lag time (tL) of 6.31 h were observed. The obtained Monod and modified Gompertz coefficients indicated that waste sorghum leaves can serve as an efficient substrate for bioethanol production. These models with high accuracy are suitable for the scale-up development of bioethanol production from lignocellulosic feedstocks such as sorghum leaves.

Highlights

Ideal crops for commercial bioethanol production in South Africa include maize, grain sorghum, and sugar cane [1]; in order to completely utilise these materials, post-harvest field waste should be employed for biofuel production
The microwave-assisted acid pre-treatment and subsequent enzymatic hydrolysis of the biomass of sorghum leaves resulted in a glucose yield of 0.153 g/g sorghum leaves
Bioethanol production, and glucose consumption were monitored throughout the fermentation process

Summary

Introduction

Ideal crops for commercial bioethanol production in South Africa include maize, grain sorghum, and sugar cane [1]; in order to completely utilise these materials, post-harvest field waste should be employed for biofuel production. Microwave radiation alters the structure of lignocellulose by emitting electromagnetic radiation, which results in the formation of thermal pockets. These pockets explode due to an increase in heat, leading to the relocation of crystalline structures within the lignocellulosic material [6]. Gabhane et al [7] studied the individual and interactive effects of acid and alkali pre-treatments using an autoclave, microwave, and ultrasonicator, and obtained a maximal reducing sugar yield of 36.84% from acid pre-treated banana waste by using microwave radiation. Despite the vast information available on lignocellulosic pre-treatment, a significant knowledge gap exists between this and the kinetic assessment of the fermentation efficiency of pre-treated lignocellulosic substrates for biofuel production

Methods

Results

Conclusion