Mutagenesis And Screening Of Pristinamycin Producing Strains And Optimization Of Its Fermentation Technology

Pristinamycins,a member of streptogramin,is produced by Streptomyces.Pristinamycins have intense antibacterial activity for G+ including methicillin-resistant Staphylococcus aureus and Enterococcus of cancomycin-resistant.So it was accepted by most specialist.Nowadays,the production of pristinamycin is still so poor that its production cost and price are very high.The purpose of this dissertation is that breeding of Streptomyces,optimization of medium and fermentation process of flask,further studying of the process in fermentor.The results are as follows:1)Six high yield strains were obtained by ultraviolet-nitrous acid mutation and ultraviolet-antibiotics resistance mutation.The genetic stability were studied by the shake flask test,the result showed that UL014 give stable,the production of pristinamycin can reach 348?g/mL,with an increase of 54.67%compared with the original.2)The optimization of fermentation medium was identified by part-factor design and orthogonal test.The production of pristinamycin can reach 455 ?g/mL,increase of 22.9%compared with the original.On the basis of optimized medium,the temperature,pH,inoculum concentration and shear force were studied.The tests indicate that the production of pristinamycin can reach 500 ?g/mL,increase of 9.8%compared with the original.The lysine(0.7 mg/100mL),serine(0.5 mg/100mL)and proline(0.3 mg/mL)were added to the medium at 68 h in Pristinamycin fermentation,the production of pristinamycin is 598 ?g/mL,with an increase of 8.7%.3)The fermentation process was identified on the basis of the fermentation culture too.The test results showed that it improved the level of fermentation that could reached 455 ?g/mL,an increase of 22.9%rather than the original.After that the mixture of amino acid was added into the fermentation medium,it turned that the level of fermentation that could reached 455 ?g/mL,an increase of 8.7%.4)The adsorption-fermentation coupling was employed in the pristinamycin fermentation process.The results show that the fermentation titer increasing by 45%than the crude,when LD605 macroporous adsorption resin was added at 8%one time in the fermentation of 28 h.5)The fermentation of Pristinamycins was tested in the fermentor with the continuity of feeding and the intermittence feeding.It showed that there was glucose effect in pristinamycins fermentation by feeding glucose continuously.It would cause the inhibition of the accumulation of pristinamycins.Afer using the intermittence feeding in the fermentation,the glucose effect was remitted.And the pristinamycins was enriched and the rate of production increased.This is very important for further study of pristnamycins in future.