Study On Breeding Of High-yield LNT-producing Strains By Nitrogen Ion Implantation

Lentinan(LNT) is an active amylose. It is a kind ofβ-1,3-glucan extracted from lentinus edodes, which has biological activity of immune modulation, anti-infection, antitumor and antiviral activity. Lentinan is not only a better medicament, but also an important hygienical factor, so it has been widely used in various areas. But the yield of LNT is not very high presently, and therefore how to improve the yield becomes more and more urgent.Lentinus edodes were implanted with various nitrogen ions implantation dosage but same energy in this study. A mutant strain WX15 was obtained.After 9 days' shake-flask cultivation, the productivity reached 4.354 mg/mL. Its LNT yield was 16.8% higher than that of the original strain,and the mutant strain had high genetic stability.The variations of livability of colony, growth rate of mycelium, mycelium biomass and the contents of lentinan(LNT) under various nitrogen ions implantation dosage were investigated. The curve of survival took a"saddle shape" with increasing N+ ion implanted doses. It got better induced mutation action when the ions implantation dosage was 1.5×1016ions.cm-2 . Based on the culture medium former, the fermentation conditions of the mutant strain WX15 was also studied in this paper. The optimum nutrient factors were determined by orthogonal experiment as follows: potato 15%, maltose 1.5%, yeast powder 0.7%,bran 3%, KH2PO4 0.3%,MgSO4·7H2O 0.2%,and the best condition of liquid culture as follows: loading volume 120mL, dose of inoculation 12%,dose viscosity 0.2%,pH 5-6,condition of(25±1)℃,shaking frequency 160 r/min, fermentation time 9 days.Thus a conclusion may be drawn that it is an effective way of mutation breeding by N+ ion implantation.