Effects of different Electrodes in the Growth of Salt and Ethanol Tolerant Yeast Isolated from Murcha of Nepal

Abstract

Many yeast species have the capability to transform various types of hexose sugars into ethanol through glycolysis. To determine the effects of different electrodes and applied voltage on glucose metabolism and ethanol production, various electrochemical combinations were tested using a 4-volt electric current. The results revealed that yeast exhibited the highest activity for ethanol production in the anode side of the graphite-graphite electrochemical cell and in the cathode side of the graphite-platinum electrochemical cell. Ferricyanide treatment did not show any significant increase in ethanol production. Nevertheless, when the yeast culture was kept at the ideal temperature of 28°C while undergoing ferricyanide treatment, a notable enhancement in yeast metabolism was witnessed in the graphite anode at 96 hrs. At this time point, the ethanol concentration increased from 16.74 ± 0.13 mg/mL at 72 hrs to 41.48 ± 0.10 mg/mL. However, the ethanol concentration dropped to 21.82± 0.12 mg/mL at 120 hrs. In the bioreactor, the highest production of ethanol by yeast was observed at 72 hrs, with an ethanol concentration of 58.76± 0.10 mg/mL. At 96 and 120 hrs, the ethanol concentration decreased to 32.29± 0.58 mg/mL and 22.66 ± 0.57 mg/mL, respectively. The results indicate that the application of a low level of voltage increased ethanol production in yeast. The use of electrochemical cells also resulted in better glucose metabolism and ethanol production in yeast compared to other general microbial techniques. The maximum percentage of ethanol produced 5.88. The presence of glucose and ethanol in the samples was confirmed via HPLC. Additionally, the 18s rRNA PCR product size was around 600 bp, and a protein of sizes 26kDa, 34kDa, and 43 kDa was observed in the sample. Overall, the study provides valuable insights into the effects of different electrochemical cells and setups on glucose and ethanol metabolism in yeast. Such research is crucial in providing necessary data and insights into the development of microbial fuel cells. Keywords: Electrochemical cells, ethanol, graphite electrode, murcha, PCR, platinum electrode, SDS-PAGE