Isolation and Characterization of a Saccharomyces Cerevisiae Strain from Olive Mill Wastewater for Efficient Bioethanol Production

The selection of efficient yeast strains with robust tolerance to complex waste substrates is a key to effective bioethanol production. This study aims to identify yeasts strains with significant ethanol production capability and tolerance to polyphenols, isolated from olive oil wastewater (OMW). Morphological identification included colony observations, where strains exhibited characteristic colony forms, sizes, and textures. Fermentability tests using Durham tubes at 30℃ for 72 h assessed CO2 production, while yeast tolerance was evaluated by exposing the strains to Sabouraud medium supplemented with increasing concentrations of OMW (10%, 25%, 50%, 75%, and 100% v/v). Ethanol production was monitored across these concentrations, revealing that strain Y17, identified as Saccharomyces cerevisiae through ITS rRNA sequencing, achieved concentrations ranging from 0.5 g/l at 4 h to 11.3 g/l at 72 h, with a corresponding yield of 0.45 g ethanol/g glucose. These results demonstrate the strain's significant tolerance and productivity under high polyphenol conditions. This work provides novel insight into the ability of a native S. cerevisiae strain to ferment undiluted, untreated OMW efficiently, without the need for detoxification or supplementation. The findings suggest that S. cerevisiae derived from OMW has strong potential for bioethanol production from industrial waste byproducts, supporting sustainable biofuel applications and offering a viable solution for waste management in olive oil-producing regions.