Enhancement of sustainable bioethanol production from microorganisms isolated from molasses and venasses

Abstract

Ethanol is one of the most important biofuels that can be produced from different renewable ‎sources. Molasses and Venasses are used as cheap raw materials in the isolation of ‎microorganisms and used molasses as renewable materials for ethanol production. Molasses and ‎Venasses are considered important by-products in the sugar industry. This study aims to isolate ‎and identify yeasts and bacteria present in both molasses and venasses to use them in the ‎production of bioethanol. Molasses and venasses samples were collected from ten different sugar ‎factories (Guirga, Savola, Deshna, Komombo, Abokorkaus, Delta, Dakahlia, Qus, Nag-hamdy, ‎Armant) and were used to isolate different microorganisms that were screened for their ‎bioethanol productivity. The results showed that the molasses samples contained more microbes ‎than venasses. Twelve isolates were molecularly identified as S. cerevisiae by PCR-specific ‎primers, while 64 isolates were bacterial isolates. All the yeast and bacterial isolates were ‎screened for bioethanol productivity. Isolate M3 showed the highest bioethanol productivity ‎‎(74%) and was identified by 16S rRNA gene sequencing as Klebsiella pneumoniae. Several ‎factors affected the production of bioethanol, including sugar concentration, urea, and ‎ammonium sulfate. When molasses was used as the carbon source, Klebsiella pneumoniae ‎produced 1% (v/v) bioethanol by utilizing 20% molasses (sugar concentration), 0.4% urea, and ‎‎0.4% ammonium sulfate. When UV-mutagenesis was used to improve the bioethanol ‎productivity, all the obtained mutants showed lower productivity compared to the wild-type (M3 ‎isolate). ‎