Isolation, identification of yeast strains producing bioethanol and improvement of bioethanol production on cheese whey / Biyoetanol üreten maya türlerinin izolasyonu, tanılaması ve peynir altı suyunda biyoetanol üretiminin sağlıklaştırılması

Abstract

Abstract Objective: In this study, bioethanol production on cheese whey (prehydrolysed enzymatically using β galactosidase by isolated yeast strains was investigated. Methods: The yeast strains were isolated from Algerian natural sources (soil and grape) and further were selected on the basis of high ethanol tolerance and high ethanol production on prehydrolysed cheese whey. The selected ones were identified by morphological, physiological and biochemical characteristics. Then, a molecular identification was carried out by amplification and sequencing the D1/D2 domain of 26S rDNA region. In addition, the operating parameters of fermentation such as temperature, pH and substrate concentration (mixture of glucose and galactose) were tested for efficient yeast strain. Results: Among the selected and identified yeast strains, three strain isolates were found to be able to produce bioethanol. These strains are Hanseniaspora opuntiae Z087A0VS, Candida tropicalis Z087B0VS and Candida tropicalis Z087D0VS with an identity of 99% and 100% respectively comparing with the stocked strains in data bank. Furthermore, Hanseniaspora opuntiae presents an ethanol tolerance ethanol up to 11% whereas the two other strains of Candida tolerate up to 12%. The fermentation parameters of most efficient strain were optimized, the temperature 30°C, pH 5 and sugar concentration (glucose and galactose) of 12.5% (w/v) are considered as optimum values for Candida tropicalis Z087B0VS. Conclusion: Candida tropicalis Z087B0VS can be considered as a good candidature for industrial bioethanol production.