High Conversion Rate Of Yeast Screening, Identification And Optimization Of Culture Conditions

In the present work, the strain 12y-5 that should be of use for production of single cell protien was selected from 14 strains of yeast isolates. The morphological and physiological description of the stain 12y-5 was presented. The yeast strain 12y-5 was identified at the species level using two yeast taxonomy systems published by .J.W.Kreger-Van Rij(1984)[24] and J.A.Barnett(1983).[19] In addition, the ability to assimilate several compounds as main sources of carbon and nitrogen was evaluated at the 500ml shake-flask and 3.7L KFL bioreactor scales. Effects of pH, temperature, concentration of dissolved oxygen and utilizable sugar on the growth rate of cells and the rate of the conversion of substrate into biomass were studied. The results were as follows:1. The yeast strain 12y-5, based on careful comparison with known yeast strains, was primarily identified as the Trichosporon sp. Nov..2. The suitable growth conditions with a high biomass were found to be at 30X), pH5.5-6.0, in 40ml of medium of 4% glucose, 2% peptone, 1% yeast extract mixture in 500ml shake-flask, 150 r/min(shaking table). The biomass and the rate of conversion were 29.3mg(dried cells/ml) and 0.747(gram dried cells/gram utilizable sugar) at shake-flask scale above for 40h, and 42.9mg(dried cells/ml) and 0.740(gram dried cells/gram utilizable sugar), respectively, in 3.7L KFL bioreactor contained 5.1% utilizable hydrolyzed sugar of maize for 20 h.3. Our results indicated that the yeast strain 12y-5 should be a potential yeast strain producing the single cell protein.