One of the most common types of pollution that has a negative impact on the biotic community in aquatic habitats is heavy metal poisoning of the water. Both essential and non-essential heavy metals can be toxic to living things if their concentrations are too high for their bioavailability. Although the toxicity of heavy metals, and especially anionic metal ions, is better known than that of cationic metal ions, it is just as toxic, if not more so. The focus of this review is on the usefulness of eukaryotic organisms like yeast, Saccharomyces cerevisiae, for toxicity assessment because they can be easily maintained and developed in controlled circumstances, thereby avoiding variability issues that arise when employing more complex organisms. Recent research has shown that the majority of cellular MTT reduction occurs outside of the mitochondrial inner membrane, and that this reduction is dependent on NADH and NADPH but is resistant to respiratory chain inhibitors.

Currently, heavy metals pollution is significantly becoming a global concern as it causes severe toxicity towards human health and the environmental condition. Intensive efforts to develop a highly sensitive, rapid, and simple toxicity assay to assess the toxic effects of heavy metals in aquatic bodies have been done. An emerging tool to solve this matter is by using microorganisms and one of them is yeast. In this study, a rapid, simple, and cost-efficient toxicity assay by using the Baker’s yeast (Saccharomyces cerevisiae) respiration assay with a tetrazolium dye (MTT) is developed as potential environmental biomonitoring tool. To achieve high sensitivity, optimization using one-factor-at-a-time (OFAT) was first carried out. The best conditions giving optimum response occurred at pH 5.8 and 30 min contact time. Molybdate and chromate exhibited exponential decay type inhibition curves with calculated half maximal inhibitory concentration, IC50 of 1.137 mg/L for molybdate and 1.247 mg/L for chromate. The Limits of detection (LOD) were 0.313 mg/L and 1.247 mg/L for molybdate and chromate, respectively. The newly developed assay can help in monitoring heavy metals pollution in rivers and agricultural areas.