ISSN 2756-3693
African Journal of Biology ISSN 2167-0413 Vol. 3 (1), pp. 186-191, January, 2016. © International Scholars Journals
Full Length Research Paper
Effects of heat and ethanol on fermentable yeast cells
Emuakpor J. Divine1*, Jacob Ifemnacho2, Esiokugbe Rejoice2 and Kalabu David2
1Department of Biological Sciences, Microbiology Unit, Fountain University, Osun State, Nigeria. 2Department of Microbiology, Ahmadu Bello University, Zaria, Kaduna State, Nigeria.
E-mail: [email protected]
Accepted 22 December, 2015
Abstract
This study investigated the effect of heat and ethanol on fermentable yeast cells. Fermentable yeast cells (Saccharomyces cerevisiae strains and non-saccharomyces species) were subjected to varying temperature (37, 40 and 44°C) and ethanol concentration (8, 10, 14 and 18%) respectively. In the research, 55.35% of the fermentable yeasts were highly thermotolerant, moderately thermotolerant (42.86%), slightly thermotolerant (1.79%) while the industrial strain was non-thermotolerant. With respect to ethanol - osmotic shock effect, 41.07% were highly tolerant, moderately tolerant (58.93%) while none was slightly or non-tolerant. Thus, there was significant difference in biomass yield obtained at different temperatures and ethanol concentrations. Furthermore, the flocculation analysis showed that 80% of the yeast cells were highly flocculant, slightly flocculant (13%) and non-flocculant (7%) respectively. Summarily, exposure of yeast cells to elevated temperatures and ethanol concentrations increase ability of cells to survive exposure to lethal heat and ethanol osmotic shock during ethanol production.
Key words: Fermentable yeasts, heat shock, ethanol, flocculation.