Isolation and identification of a yeast strain involved in the degradation of Marrakech olive mill wastewater

Yeasts are widely used in various sectors of biomedical research, biotechnologies and environmental contexts. During the treatment of olive oil mill wastewater (OMW) by yeasts, extensive degradation of the polyphenols responsible for the highly toxic nature of this effluent occurs. In this study, one yeast isolate was selected for its ability to use the phenolic compounds in OMW as the sole carbon source for growth. The treatment of OMW using this isolate reduced the levels of polyphenols by about 50% and the fats by over 80%. Analysis of the polyphenol pool by HPLC revealed the presence of 6 compounds, most of which had disappeared after 5 and 25 days of treatment. Using API ID 32C, the taxonomic study of the selected isolate was found to be 99.9% identical to Candida valida. However, the molecular data using the Rep-PCR technique showed 83.6% similarity to Pichia membranifaciens and 80.6% to Pichia anomala.