Fermentation And Separation Coupled The Preparation Shell Oligosaccharides

High yielding chitosanases strain: Penicillium sp. ZD-Z1 was applied in the shake-flask culture. The culture conditions were optimized by controlling the inoculation volume, medium volume, initial pH, concentration of chitosan and metal ions. The enzyme-production curve and substrate concentration curve were determined in the 5 L fermentation tank fetch culture and the influence of air flux is studied.On the basis of shake-flask culture and fetch fermentation, the coupling of semi-continuous fermentation and ultrafiltration was developed on chitosan-oligosaccharide preparation in the 5 L fermentation tank. The influences of dilution rate, chitosan concentration and fermentation time on biomass and yield were studied and different operation conditions of ultrafiltration were also tested. It was found that the optimal operation condition of fermentation was under dilution rate of 0.15 h^-1, chitosan concentration of 3% and fermentation time of 96 hours. Compared with batch fermentation, yield of chitosan-oligosaccharides was increased 5-fold after coupling. It was shown that the membrane flux kept steady under a operating pressure of 0.5 M Pa. Separation of chitosan-oligosaccharides with different molecular weight was achieved based on the use of ultrafiltration membrane with different molecular weight cut-off (MWCO).Chitosan-oligosaccharide powders with high purity were acquired by spray drying. Conditions used in the spray drying were as follows: feed-in velocity of 6 ml·min^-1, temperature at entrance of 160℃, spray airflow of 27 m³·h^-1. The relative molecular weight of dryness product S₁ and S₂ were 11247 and 3402 by the use of HPLC.