Assessment of stress resistance of industrial strains of Saccharomyces cerevisiae for designing selection media

The two main methods for obtaining microbial strains with specific characteristics for application in the industry are isolation from natural sources and using random mutagenesis. Characterization of all isolated strains is very time-consuming and expensive. In this study the tolerance of some strains of Saccharomyces cerevisiae to different stresses was measured and the association between these stresses and tolerance to osmotic pressure and production of intracellular trehalose determined, aiming at applying the results to designing selection media. The viability [percent cell survival] of different strains of Saccharomyces cerevisiae was assessed by exposure to a 3M Nacl solution, a 40% sorbitol solution, a freezing shock at -20°C, and a heat shock at 52°C. In addition, the intracellular accumulation of trehalose was determined by the antrone reagent. The associations between these factors and resistance of Saccharomyces cerevisiae strains were then determined using statistical tests. Strong correlations were observed between resistance to NaCl- and sorbitol-introduced stress and strains of Saccharomyces cerevisiae [p<0.01]. There was also a strong association between intracellular trehalose accumulation and resistance to heat shock [p<0.01]. While sugars can not select osmotolerant cells, Nacl is a very strong selector for more specific isolation of more resistant cells in a suspension. Similarly, heat shock stress is very efficient in selecting cells with a higher intracellular trehalose accumulation in a suspension

study on the application efficacy of solvent-detergent [S/D] treatment in the process of purifying factor VII from prothrombin complex

The risks of transmitting viral infection by blood and plasma-derived products have long been known and still remain an area of concern. In this study, in the process of purifying human factor VII from prothrombin complex, S/D treatment using tri-n-butyl phosphate and Tween 80 was employed and its capability and efficacy was studied. The results indicated that the process did not affect the biological function of the essential coagulation factors studied. In addition, the process was shown to be effective on enveloped viruses, where its inactivation factor for the model used, Herpes Simplex type I, was 5.5 logs. However, the procedure was not effective on poliovirus which was used as a model for non-enveloped viruses. It is therefore concluded that for increasing viral safety it is best to apply at least one more inactivating procedure which will be effective on non-enveloped viruses as well