Yeast extracts production from Whey by utilization of local isolate Kluyveromyces marxianus

Abstract

local isolated Kluyveromyces marxianus from local sources (yoghurt) was used for yeast extract production. Optimum conditions of chemical and physical properties of this isolate were identified for the optimal growth and biomass production, so the optimum temperature and pH were 30C, 5.0, respectively, the speed of shaker incubator was 200 rpm, the inoculum size was 1×106 CFU/ml. The optimum fermentation medium was included the non-protein whey which fortified with 10% lactose, 0.2% (NH4)2HPO4, 2% Na2HPO4 and 2% of heated hydrolyzed yeast, the obtained biomass was about 0.52 g/100 ml, fermentation efficiency was 16.7%.The produced biomass under optimum conditions referred above was applied for yeast extract production by using sonicator and electric vacuum oven for drying the biomass. The chemical composition of the resulted yeast extract was: 50% protein, 31.6% total carbohydrate, 6.8% glucan, 5.4% moisture. The resulted yeast extract was involved in the composition of some culture media, and comprised with standard yeast extract. The growth yield in these media which was determent by measuring optical density was estimated to those of media with standard yeast extract, which were 0.539, 0.552 respectively in MRS and 1.05, 1.15 respectively in Davis's yeast salt broth.