The Research On Lincomycin Biosynthesis And Fermentation Process Optimization

This is an scale-up experiment on lincomycin production in a15L fermentor, which is based on a positive effect of alanine or trimrthylamine addition in shake flask studyaddition in shake flask study.By using high-yield mutated strain, the study mainly focuses on the influence of the bacterium age of the secondary seed on fermentation potency.The results of the study as follows:first,it was found that using secondary seed at23h of culture result in a maximum titer;second,pH value at6.8-7.0in the middle and later period of fermentation is favorable to the biosynthesis of lincomycin.During the fermentation of S. lincolnensis, the enzymatic activity of pyruvate kinase (PK) is inhibited by using alanine, which consequently increases the flux of lincomycin. In the fermentation process,0.1g/L alanine is added in the fermentor at Oh,12h and24h respectively and the result shows that the optimal time for alanine addition is at24h. The yield of lincomycin is steadily increased by26%when0.1g/L alanine is added at24h. The addition of trimrthylamine could inhibit the enzymatic activity of anthranilate synthase(ASA).By adjusting various parameter of fermentation process,the lincomycin titer in a15L fermentor is improved by35%when0.02%trimrthylamine was added at24h.Gene transcription level of gene lmbG and genes encoding AAIR,G6PDH and GS were studied by comparing the different yields of the wild-type strain and the mutated strain at different protein spots,gene encoding16s RNA was used as housekeeping gene.It was found that gene lmbG,and genes encoding AAIR,G6PDH and GS in the mutant strain were transcribed more than that of the wild-type strain.Actually the statistics indicated that the fermentation titer of the mutated strain is28%higher than that of the original strain.And the results indicated that the addition of alanine decreased the transcription of gene encoding PK,while trimrthylamine might affect the expression of gene encoding ASA.Transcription of both the gene lmbG and gene encoding G6PDH were enhanced by the addition of either alanine or trimrthylamine respectively.