The effects of paraquat and arsenic acid on the growth of distiller's yeast

The effects of the defoliants arsenic trioxide and paraquat on the growth of Saccharomyces cerevisiae were studied. It was found that 10 and 10 M concentrations of the defoliants did not significantly inhibit the growth of the distiller's yeast, while inhibition -3 -4 -3 was observed at 10 and 10 M concentrations. At 10 M concentrations of both defoliants, the growth of the yeast was inhibited completely in both tryptic soy broth and in a semi-synthetic medium containing glucose as the carbon source. Growth curves revealed an immediate toxic effect on yeasts grown in paraquat-treated media, while the number of viable cells remained constant for a short period of time in media containing arsenic trioxide.