5082
GOMAA NOUR EL-DIEN ABD EL-RAHMAN EID
PRODUCTION OF BAKER'S YEAST FROM SACCHAROMYCES CEREVISIAE STRAINS RESISTANT TO SOME CONTAMINANTS
Baker's yeast, Saccharomyces cerevisiae, molasses, resistance, lead, cadmium, copper, nickel, yield, total viable cells and gassing power.
The aim of this study was to determine the heavy metals content of crude molasses and treated molasses samples collected during 2013 seasons from El-Hawmdia for Chemicals Factory. Nine S. cerevisiae strains were tested to select the best strains able to resist lead, cadmium, copper and nickel as compared to factory strain. The ten strains were screened on the basis of their resistance to heavy metals at different concentrations (0, 2, 4, 8, 12, 16, 20 and 24 ppm) for lead or copper and 0, 0.5, 1, 2, 4, 6, 8 and 10 ppm for cadmium or nickel.The slope values of yield, total viable cells and gassing power of produced baker's yeast as well as concentrations of lead, cadmium, copper and nickel in produced baker's yeast were investigated as indicators of strains resistance to heavy metals. Also, the combined effect of nickel and copper on selected S. cerevisiae strains was studied.In addition, the effect of molasses treatment by different methods on decreasing of heavy metals was investigated. The treated molasses by cation exchange resin then sulfuric acid (the best treatment) was used as growth medium of selected strains and compared with synthetic medium for selection the best medium for heavy metals resistance.Moreover, the effect of storage on quality of produced baker's yeast through determination of total viable cells, gassing power, trehalose and glycogen content of selected S. cerevisiae strains was investigated. Finally, application of the selected strains in production of balady and pan bread was evaluated.
2015
Ph.d
Ain Shams
Agriculture