Production and Characterization of Bioethanol Using Native Microbial Isolates from Decomposed Maize Cob via Simultaneous Saccharification and Fermentation

Abstract

Maize cob a major component of agricultural waste composed mainly of cellulose that can be converted to bioethanol through fermentation as means of waste management. Achieving enhances bioethanol yield without ascertaining proper conversion pathway may be subjective.  Therefore, this research aimed at converting maize cob to bioethanol through fermentation using natives microbial isolates from decomposed maize cob via Response Surface Methodology. Microbial strains used were Pichia kudriavzevii strains with accession number KP998095.1 and MN861069.1. A pH value of 5.5 corresponded to bioethanol yield of 52.45 g/L, pH was observed to be sensitive to fermentation hence influence the extent of fermentation process. Optical density (O. D_610nm) of 2.2 after eight (8) days of fermentation corresponded to bioethanol yield of 52.45 g/L. The growth pattern observed in most of the samples followed a typical microbial growth pattern depicting lag, log and stationary phases. Reducing soluble sugar of 23.5 mg/L on enzyme hydrolysis corresponded to bioethanol yield of 52.45 g/L, reducing soluble sugar content of the experimental samples were observed to decrease as the fermentation progresses. The infrared spectra of the optimum sample distillate of bioethanol from the fermentation revealed the presence of OH at 3311.7 cm^-1 stretching band and C = C at 1636.3 cm⁻¹ stretching band. The elemental compositions of the distillate were oxygen (31.03%), hydrogen (9.74%), carbon (56.85%), nitrogen (1.92%) and sulphur (0.46%) which confirmed the presence of bioethanol. The empirical formula of the best distillate using C, H, and O compositions (%) was found to be C₂H₅OH, hence revealed the presence of bioethanol. The result of the GC-MS analysis showed that mass spectra comparison of the various peaks revealed the presence of bioethanol as the largest peak with 76.38% ethanol by concentration.  Maize cob can be said to be a promising feedstock for bioethanol production using native microbial isolates.

Received: 16 August 2024 | Revised: 6 September 2024 | Accepted: 16 October 2024

Conflicts of Interest

The authors declare that they have no conflicts of interest to this work.

Data Availability Statement

Data available on request from the corresponding author upon reasonable request.

Author Contribution Statement

Yakubu Atiku: Conceptualization, Methodology, Software, Formal analysis, Investigation, Resources, Data curation, Writing - original draft, Writing - review & editing, Visualization, Supervision, Project administration; Surajudeen Abdulsalam: Conceptualization, Methodology, Data curation, Writing - original draft, Writing - review & editing, Visualization Supervision, Project administration; Jibrin Mohammed: Methodology, Software, Writing - review & editing, Visualization, Supervision, Project administration; Saeed Ahmed: Methodology, Writing - review & editing, Visualization, Supervision, Project administration; Ahmed Inuwa: Software, Writing - review & editing, Visualization.