Screening Optimum Strain On Fermentation From Straw In Solid State Fermentation

Initial strain fungus is Trichoderma, which can produce cellulase obtained from Microbiological Lab of Shangdong University of China. The best condition under this strain produce cellulase has been studied, the highest level of CMCase, Fpase, and Bgase 78.61U/g, 21.OIU/g, 33.61U/g respectively on 0.5% glucose after growing 132 hours. After many times UV mutagenesis , combining agar plate screening technique, we isolated mutant strains, whose stability of producing cellulase are good under the same culture condition, CMCase, Pgase & Fpase from 78. 61U/g, 21. OIU/g & 33. 61U/g to 235. 171U/g, 91. 61U/g and 119. 561U/g respectively, increased by 3, 4. 75, 3. 5 times respectively to starting strain. In this paper, the initial yeasts are four strains, the strains 1ff & 3ff fermentative ability are high , up to 6.978%, 6.823% respectively;the last two have high thermoduric tempreture(38扖). We used the protoplast fusion technique to breed the thermoduric yeast. Protoplast fusion between high yielding ethanol yeast 1ff & 3ff and thermoduric yeast 2ff was made. The bodies for fusion were hapoid and diploid protoplast, and 2ff protoplast was inactived by UV. After fusion resulted from single梡arent was inactived and complementation of the parental nutrient makers, fortunately we obtained three ideal fermentative fusants F5, F7, F14, At high temperature. Testing and identifying their ploidy.. thermostability.. biological characteristics (cell size, cell morphology.. sporulating ability and fermentability etc), the results showed that they were uninucleate fusants. The ethonal fermentation tests from fermenting media were carried out at 38扖 for 72 hours, the fermentative ability of them were higher than that of 1ff 30 C, the ethanol production was increased by3. 7%percent. After many repertive fusional experiments, we compared PEG fusion with electrofusion the former had lower frequency than the latter. The most highest fusion frequency: the former抯 was 3. 1 >( 10~, however the latter抯 was 5.64X104(underUV 11KV, pulse width 1OL抯, pulse interval lOs, pulse number 3).