Mutagenesis can generate genetic diversity and novel phenotypes in yeast strains. This study evaluated physical and chemical mutagenesis for improvement of an industrial Saccharomyces cerevisiae opaque beer strain. The yeast strain was exposed to mutagens, long enough to cause 50-95 % lethality with subsequent assessment of surviving cells for favourable characteristics. Yeast batches were mutagenized using ethyl methanesulfonate (EMS), and by exposure to ultraviolet light and visible light. EMS caused a dose-dependent decrease in survival from 100 % viable cells without EMS addition, to 10 % at 100 μg/mL, and 0 % at 200-300 μg/mL. There was approximately 10 % survival under ultraviolet light exposure observed at 25 minutes. Ultraviolet light resulted in approximately 10 % survival at 25 minutes of exposure. Visible light showed negligible mutagenic effects, with white light had the least impact on survival. EMS mutagenized cells achieved 4% alcohol content in 48 hours, versus 72 hours for controls, indicating accelerated fermentation. EMS mutants utilized 37 % more sugar on average than controls but produced lower total acidity in the final product. Thus, EMS mutagenesis produced favourable phenotypes including faster fermentation, higher alcohol yield, increased sugar consumption, and low off-flavours. With appropriate screening, EMS mutagenesis could generate improved opaque beer strains with desirable industrial characteristics. This study demonstrates the potential of random mutagenesis to sustainably enhance yeast strains for modern beer production.