Potential of R5I3 Isolate for Bioethanol Production on YPG Medium with Glucose and Fermentation Time Variations

Bioethanol production in Indonesia remains low despite the country’s rich biomass potential, partly due to the lack of native ethanolproducing microbes. This study evaluated the potential of R5I3 isolate to produce ethanol using Yeast Peptone Glucose (YPG) medium with glucose concentrations ranging from 8–20% (w/v) and fermentation durations of 1–4 days. The results showed that R5I3 was capable of surviving and producing ethanol across all treatments. The highest ethanol yield was recorded in the 18% w/v glucose treatment with a fermentation period of 4 days, producing 9.75 ± 0.35% (v/v) ethanol, with a final pH of 3.47 ± 0.55, total dissolved solids of 6.30 ± 0.14°Brix, and reducing sugar of 0.688 ± 0.008 mg/mL. These findings indicate that R5I3 isolate has strong potential as a microbial agent for bioethanol production under varying glucose concentrations and fermentation times.