Isolation of lipase and citric acid producing yeasts from agro-industrial wastewater

Production of agro-industrial waste pollutants has become a major problem for many industries. However, agro-industrial wastes also can provide alternative substrates for industry and their utilization in this manner may help solve pollution problems. The aim of this study was to isolate yeasts from wastewater treatment plants that could be used to remove pollutants such as glycerol, paraffin and crude oil from the agro-industrial wastewater. In this study a total of 300 yeast isolates were obtained from samples of agro-industrial wastes, and two strains (M1 and M2) were investigated for their ability to produce valuable products such as lipase and citric acid. Identification tests showed that these isolates belonged to the species Yarrowia lipolytica. The Y. lipolytica M1 and M2 strains produced maximum levels of lipase (11 and 8.3 U/ml, respectively) on olive oil, and high levels of citric acid (27 and 8 g/l, respectively) on citric acid fermentation medium.