Enhancement of PHA Production by a Mixed Microbial Culture Using VFA Obtained from the Fermentation of Wastewater from Yeast Industry

Wastewater from the yeast production industry (WWY) is potentially harmful to surface water due its high nitrogen and organic matter content; it can be used produce compounds of higher commercial value, such as polyhydroxyalkanoates (PHA). PHA are polyester-type biopolymers synthesized by bacteria energy reservoirs that substitute petrochemical-derived plastics. In this exploratory work, effluent WWY was PHA, using a three-step setup mixed microbial cultures involving one anaerobic two aerobic reactors. First, volatile fatty acids (VFA; 2.5 g/L) were produced on an batch reactor (reactor A) fed with WWY, heat pretreated sludge inoculum eliminate methanogenic activity. Concurrently, PHA-producing enriched synthetic VFA in sequencing (SBR, C) operated for 78 days. Finally, polyhydroxybutyrate (PHB)-producing B) assembled raw distilled substrate. A maximum accumulation 17% PHB based cell dry weight achieved yield 1.2 g PHB/L when feeding effluent. Roche 454 16S rRNA gene amplicon pyrosequencing showed community dominated bacterial species Paracoccus alcalophilus (32%) Azoarcus sp. (44%). Our results show promising rates outperform previously reported obtained real substrates cultures, demonstrating sustainable approach less prone contamination than pure culture.