Enhanced Bioethanol Production from Alkaline-Pretreated Rice Bran Using Locally Isolated Zymomonas mobilis

Abstract

Bioethanol has emerged as an important alternative renewable energy source both an economic and industrial resource providing significant benefits for a several sectors in the world today. The substrate was procured from a rice mill at Argungu, Kebbi State, while the feedstock of the inoculum was isolated from sewage from a local juice vendor, deteriorated fruits, and hostel. The isolate was identified using both biochemical and 16S molecular approaches. Alkaline hydrolysis of the rice bran was conducted using analytical grade reagents, while proximate analysis was performed on the raw rice bran, treated, and conditioned samples. Response surface methodology was applied for optimization using Design Expert. The molecular identity of the bacteria was established to be Zymomonas mobilis with a 99% identity with already existing flora in GenBank. Ethanol tolerance and productivity of the isolate. The study identified that the inoculum was thermostable and partitioned excellently with proportionate increase in the ethanol concentration. Proximate composition of the rice bran showed a significant increase in nutrient in pretreated and conditioned samples than the raw substrate. The study was fitted into a quadratic model with an ANOVA of 0.0043 and F-value of 4.44 with a significant iteration showing that inoculum size and temperature having a significant effect on the production of bioethanol production of 22.85 mg/L. The academia and industry must synergize to develop a more robust and efficient technology to advance bioenergy production and commercialization.