Conversions of olive mill wastewater‐based media by Saccharomyces cerevisiae through sterile and non‐sterile bioprocesses

Abstract

AbstractBACKGROUND: Olive mill wastewaters (OMWs) are an important residue and several methods have been proposed for their treatment.RESULTS: Remarkable decolorization (~63%) and phenol removal (~34% w/w) from OMW was achieved. In glucose‐based flask sterile cultures, enrichment with OMWs increased ethanol and biomass production compared with cultures without OMWs added. Flask sterile and un‐sterilized cultures demonstrated similar kinetic results. Batch‐bioreactor trials performed showed higher ethanol and lower biomass quantities compared with the respective shake‐flask experiments, while cultures used under un‐sterilized conditions revealed equivalent results to the sterile ones. In non‐sterile bioreactor cultures, OMWs addition enhanced biomass production in comparison with culture with no OMWs added, whereas ethanol biosynthesis was not affected. The maximum ethanol quantity achieved was 52 g L−1 (conversion yield per sugar consumed of 0.46 g g−1) in a batch bioreactor non‐sterilized trial with OMW–glucose enriched medium used as substrate, that presented initial reducing sugars concentration at ~115 g L−1. Fatty acid analysis of cellular lipids demonstrated that in OMW‐based media, cellular lipids containing increased concentrations of oleic and linoleic acid were produced in comparison with cultures with no OMWs added.CONCLUSIONS: S. cerevisiae simultaneously produced bio‐ethanol and biomass and detoxified OMWs, under non‐sterile conditions. © 2012 Society of Chemical Industry