Antibiotics Parker Prime Fermentation Conditions Optimization And Synthetic Gene Preliminary Study,

X.nematophila is a symbiotically bacterium associated with insect pathogenic nematodes.It can produce many antibiotic substances that have wide bioactivities,such as antibiotic,antimycotic,insecticidal,nematicidal,antiulcer,antineoplastic and antiviral.So it is highly possible that the Xenorhabdus nematophila would become a kind of bio-resource that have exploitation potential and prospect of application.It would play an important role in the health and agriculture area.In this paper,we study the fermentation medium,culture condition and antibiotic-associated gene preliminarily.The primary results are as follows:1.The carbon,nitrogen and inorganic salt was reselected based on the basic fermentation medium,The result shown that sucrose is the best carbon,Yi peptone is the best nitrogen and KH₂PO₄ is the best inorganic salt.The fermentation culture medium was optimized with central composite Rota table design.The optimized fermentation medium was:Yi peptone 6%, Sucrose 4%,KH₂PO₄ 0.038%,Sodium chloride 0.5%.After optimization,the antibiotic output increased by 79.5%from 146ug/ml to 262ug/ml compared with the initial output of fermentation medium.2.On the process of optimizing culture condition,fermentation temperature,primary pH of fermentation medium,flask column,inoculation content have been studied.The result shown that the optimum temperature is 28℃,optimum pH 6.5,flask column 75ml/500ml,shaker velocity 180 r/min,best inoculation content 7%,After the optimization of fermentation medium and culture condition,the antibiotic output has raised by 113.7%.3.The effect of the antibiotic Su-Parker inhibitions to Phytophthora infestans is determined,the EC₅₀ of Su-Parker inhibitions to Phytophthora infestans is 0.28μg/ml in vitro method and it can inhibit the incidence of Phytophthora infestans at the concentration of 4ug/mL or above in vivo method.4.The homologous recombinant fragments of Xna gene are amplified by the method of overlap extension PCR,The homologous recombinant vector is constructed successfully by cloning the amplified recombinant fragments to the suicide vector of pJQ200,and then transformed into X.nematophila var.pekingensis by two parent's conjunction.The conjunction condition optimization results show that the conjunction efficiency reaches the highest level when the ratio of donor bacterium of E.coli S17-1 and recipient bacterium of CB6 bacterium is 2 and conjunction time 8 hour.