Isolation and identification of yeast strains capable of producing single cell protein from whey in co-cultures with Saccharomyces cerevisiae

In this study, twenty-five whey samples collected from dairy industries in the city of Isfahan. The samples were cultured on malt extract broth (MEB) and yeast extract glucose chloramphenicol agar (YGCA) media. Eleven yeast strains (designated M1 to M11) were isolated from the culture. The strains were identified by their morphological and physiological properties. Betagalactosidase activity in the yeast strains showed that a strain of K. lactis designated as M2 had highest enzyme activity (up to 8103 EU/ml). The isolated yeast strains were examined for their ability in reduction of the biological oxygen demand (BOD). The results demonstrated a high level of reduction in the M2 strain. This strain was also found to have highest level of single cell protein (SCP), production (up to 11.79 g/l dry mass cell). The co-culture of the isolated yeast strains with Saccharomyces cerevisiae resulted in the highest biomass yield up to 22.38 g/l dry mass cell and significant reduction in initial BOD. Together, the data showed that the isolated yeast strain could be of valuable application in bioconversion of whey.