Study On The High-yielding Strain Improvement And Culture Optimization For Ascomycin

Ascomycin is another immunosuppressant binder which is developing after CsA. It can prevent a variety of transplant rejection and is especially applicable to liver transplant.There is a high affinity binding between Ascomycin and FKBP,and is easy to inhibit the dephosphorylation of calmodulin phosphatase by binding and which is essential for activation T cell transcription factor NF-AT in the transfer to calmodulin phosphatase dephosphorylation.So it can stop targeting signal transmittion pathway intracellular.The biological effects of stoping signal transmittion is to hinder the formation of inflammatory cytokines,including interleukin-2(IL-2).IL-2 is a most important growth factor and activating factor for T-cell growth,and Ascomycin on IL-2 inhibition of the formation is more stronger than CsA.The immunosuppression of Aseomycin is about 10 to 100 times than CsA.Moreover some features of ascomycin,such as low acute and chronic rejection rate,and low infection rate,less doze of hormone,reversed acute rejection and less adverse reaction than CsA make it to replace the CsA on organ transplant market to become the preferred immunosuppressant.Ascomycin can be producted through both chemical synthesis and biosynthesis. Microbial fermentation does not need large number of organic solvents and the composition of fermentation liquid waste is,protein and inorganic salts.So, fermentation is essentially a green and environment-friendly biochemical process known as Green bioreactor.In this paper,based on an original Ascomycin producing strain,we gained a M-2-33 strain through natural isolatedand its output is 13.8 mg/L.Then M-2-33 was mutagenized with UV and NTG.Eventually a mutagentic strain M-7-21 was isolated and its ascomycin output is 64.2 mg/L which is about five times than its original production strain M-2-33.Fermentation medium of M-7-21 was optimized.At the same time,somefacters such as age,inoculum size,temperature,carbon,nitrogen and precursor substances on the impact of fermentation were experimented.The optimum conditions for fermentation as follows:Containing soluble starch3.5%,soybean powder 3%,glycero11%,peptone beans1%, potassium dihydrogen phosphate0.08%,calcium carbonate0.4%, 10%of age 48 h of the seeds were vaccinated,and after culturing 24 h,add 0.15 per cent shikimic acid,28℃,220 r/min,fermented for 96 h.Ascomycin final output reached 131.7 mg/L.