Saccharomyces pastorianus as cell factory to improve glutathione production using novel fermentation strategies

Abstract

Scountries as well as under tropical climates. The aim of this study was to optimized conditions for growth and ethanol production of thermotolerant Issatchenkia sp. S1 in enrich medium. Issatchenkia sp. S1 showed weakly grown in YM medium with sucrose, lactose, glycerol, manitol, maltose, cassava starch or potato starch as carbon source. When either glucose or fructose was used as carbon source in YM medium, the better growth of Issatchenkia sp. S1 was performed. Glucose, fructose and other N sources were used for determining the optimal concentration for growth and ethanol production in shaking flask at 200 rpm and incubation at 40 • C showed the highest ethanol production (u = 0.205 ± 0.008 h −1 , Qp = 2.328 ± 0.040 g/L/h, Yps = 0.511 ± 0.009 g/g and maximum ethanol concentration = 55.877 ± 0.962 g/L). In 2 L fermenter experiment, aeration rate and agitation speed were varied. The agitation speed at 500 rpm with no aeration in YM medium with 100 and 2 g/L (NH 4 )2SO 4 at 40 • C showed the highest of u (0.370 ± 0.009 h −1 ), Qp (1.886 ± 0.056 g/L/h), Yps (0.516 ± 0.026 g/g) and ethanol concentration (49.991 ± 1.495 g/L). The ethanol production by Issatchenkia sp. S1 was scale up to 10 L fermenter. The results in 10 L batch culture were lower than that of 2 L fermenter (u = 0.355 ± 0.012 h −1 , Qp = 1.335 ± 0.104 g/L/h, Yps = 0.431 ± 0.005 g/g and maximum ethanol concentration = 42.434 ± 1.699 g/L). Furthermore, the ethanol production by Issatchenkia sp. S1 in 10 L fermenter was improved by fed-batch operation by adding glucose for increasing the production of ethanol. A liter of 350 and 400 g of glucose syrup were added at 12 and 24 h after fermentation showed the highest ethanol production (Qp = 1.716 ± 0.150 g/L/h, Yps = 0.506 ± 0.011 g/g and maximum ethanol concentration = 77.810 ± 1.879 g/L). Additionally, the production of some organic acids detected by using HPLC technique was investigated in 10 L batch fermentation. Oxaloacetic acid (OAA) is major product of organic acid production during log phase and reduces when glucose depleted. The highest concentration of OAA was 3.035 ± 0.252 g/L at 30 h after fermentation.With increasing technological development world, there is currently a major concern with respect to the huge losses resulting from corrosion, thus requiring the development and creation of new techniques for their effective combat and control. Chemical, petrochemical industries and hydroelectric power are places favorable to the development and proliferation of microorganisms. When the corrosion of the metallic material if processes under the influence of microorganisms, it is called biocorrosion or microbially induced corrosion (MIC). There is now consider-able evidence that most bacteria are found colonizing surfaces in organized biofilms communities rather than growing in suspension as individuals. Biofilm is a structure community of bacterial cells embedded in a self-production extracellular polymeric matrix and adherent to an inert or living surface. This work had as main objective ...