| ?-PL is obtained through the way of the microbial fermentation.It is a significant antibacterial activity,safe,non-toxic,water-soluble and heat stability are very good new biological preservatives.In this study,the fermentation process of Streptomyces coelicolor UN9 was studied by mutagenizing the high-strain strain UN9.The main results of this project are as follows:?1?Streaking of Streptomyces aureus UD20 by AEC resistance screening,NTG mutagenesis,UV-induced lithium lysing and nitrite mutagenesis,combined with methylene blue screening to get a final yield of 0.619 g·L-1 named Streptomyces aureus UN9 Of the high-yield bacteria,compared with the output of UD20 0.368 g·L-1 increased by 68.2%,and bacteria UN9 can be stable genetic.?2?The effect of exogenous lysine on the biosynthesis of ?-PL was studied.The results showed that the yield of UN9 was the most significant,and the addition of lysine was not added Acid 0.610 g·L-1 increased to 0.721 g·L-1,yield increased by 18.2%.?3?Streptomyces averaged fungi of UN9 with a glucose source of 5 L fermentor natural fermentation experiments,bacteria UN9 production reached 1.802 g·L-1,shake flask fermentation is 2.499 times.And then through the carbon source of the feeding operation,making the yield again significantly increased to 6.908 g·L-1,the natural batch fermentation of 3.834 times.Aiming at the problem of reducing the activity of UN9 and the death of Streptomyces homiliformis in the late fermentation stage,the method of adding the yeast powder to the post-fermentation of bacteria UN9 was put forward,and the biomass and growth ability of Streptomyces lividans were increased to 44.46 g·L-1,the yield is further increased to 9.216 g·L-1.?4?The results showed that glycerol was the fermentative carbon source of Streptomyces aurei in addition to glucose,and explored the double carbon source fermentation of Streptomyces coelicolor.The final ratio of glucose and glycerol was 20:30,which was higher than that of single glucose the carbon source increased by 31.7%,which was 13.3%higher than that of single glycerin,reaching 0.815 g·L-1.?5?pH is an important factor affecting the metabolism of Streptomyces UN9,and the bacterium UN9 was fermented at different pH?3.8 and 4.0?,and the bacteria of the double carbon source were tested in the fermentation system pH 3.8 and 4.0 production reached 11.657 g·L-1 and 11.637 g·L-1,respectively.In order to increase the rate of synthesis of Streptomyces avermitilis,the two-stage pH control?24-72 h,pH control at 3.8,72 h after pH control at 4.0?,so that the production of Streptomyces albus UN9 further increased to 13.893 g·L-1. |
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