Saccharomyces cerevisiae strain 14-12 is a highly ethanol-tolerant organism. It can grow in the presence of 13% ethanol but growth is completely prevented at 14% ethanol. A relationship was detected between yeast lipids and ethanol tolerance. A gradual decrease of lipid content was recorded as the concentration of supplemented ethanol increased. Moreover, free fatty acids were comparatively decreased in these lipid extracts. When separately added to media with 14% ethanol different lipids produced varied stimulatory effects on yeast growth. Maximum yield of yeast growth was obtained at 14% ethanol in the presence of lecithin, palmitic acid and cholesterol. Yeast lipids produced in the presence of these fractions are characterized by a relatively high percentage of free fatty acids. The change in the percentage of free fatty acids was shown to be the controlling factor in ethanol tolerance.

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Zinc oxide nanoparticles (ZnO NPs) were confirmed in this work as a good antioxidant source. They were biosynthesised by the preformed biomass of Aspergillus carneus when contacted with 1 mM zinc nitrate solution of pH 9 after 24 h at 150 rpm and 30°C. The biosynthesised NPs were moderately distributed, quasi-spherical in shape with clear edges and the average size of 8-12 nm. The NPs retained full stability at 4°C for at least six months. Their zeta potential was found to be 18.3 mV. Crystalline nature of the ZnO NPs was suggested from diffraction rings appeared as lighted spots on the selected area electron diffraction pattern and confirmed by the X-ray diffraction analysis. High radical scavenging activities (RSA) were found against peroxide (O 2− 2) and 2,2-diphenyl-1-picrylhydrazyl (DPPH). Good activities were also recorded against hydroxyl (OH −) and superoxide (O − 2) radicals. This potential RSA can be rendered to the adsorbed biomolecules on the NPs surface especially the phenolic compounds detected by Fourier transform infrared analysis.

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