Studies Of Kinetics And Optimization Of Conditions For Producing Single Cell Protein By Fermentation Of Potato Residue And Waste Water

Potato residue, one of the agricultural waste products obtained in high quantities during starch production, contains starch, cellulose, hemicelluloses, pectin, proteins, free amino acids and salts. It exhibits physical and physicochemical properties of a typical colloid. The waste water of the starch industry comes from two parts. One for the waste water is generated by cleaning potatoes. The other is from extracting section. Potato residue and the waste water contain a lot of nutrient which cannot be effectively used, and resulting in a serious waste of resources. At present the problem of lack of the protein resources is more and more serious in the worldwide. Thus, it is an important way to development and utilize single cell protein produced by microorganism.The aims of the current study were to follow:(1) reduce the pollution of potato residue and waste water produced by starch industry to the environment.(2)transfer the potato residue and waste water into cell protein as animal feed though fermentation. Cell protein was produced from the mixture of potato residue and waste water by fermentation with mixed microorganism in an aerated 5-L fermentor.Through optimizing bioprocess variables, the best strain combination was Bacillus pumilus: Candida utilis: Aspergillus niger: Trichoderma viride: Trichoderma koningii: Trichoderma harzianum=7:2:0.25:0.25:0.25:0.25.And the best fermentation condition was inoculum concentration at 1‰, temperature at 30℃, and air flow at 0.1vvm. The results of feeding the mouse with the fermentation product at the best fermentation condition showed that the weight of the male mouse fed with the fermentation product was 34.70g after 30 days'feed, which was similar with the weight of the male mouse fed with normal mouse grain at 34.44g .The weight of the female mouse fed with fermentation product and normal mouse grain separately was 29.75g and 28.78g. All of the results indicated that it was feasible that fermentation product could replace soybean as a protein feed. Kinetic analysis at the best fermentation condition showed that the values of cell mass yield (YX/S, g/g) and cell mass productivity(QX, g/L h) were 0.878 and 0.026, and the crud protein productivity(QCP, g/h L) was 0.130.