The Screening Of Lincomycin Producing Strain With High Yield And The Regulating Of The Metabolic Pathway

This topic made a comparison of several mutagenesis methods on the advantages and disadvantages. And we chose the EMS2h+UV3os as the best mutagenesis method. On the basis of analysing the existent metabolic pathways of Streptomyces lincolnensis, we found propylproline and glutamine are the important metabolic intermediate materials. Through reviewing literatures, two structure analogues were found. They were used as screening materials after mutagenesis. We chose Streptomyces lincolnensis07-5as an initial strain. After mutagenesis three times by EMS+UV and screening by two structure analogues, mutant P2-A6-P10-10was selected. Its yield was increased by45%. When the structure analogue of propylproline was added to broth during fermentations with the mutant and initial strain, their yields were increased by13.7%and13.8%respectively. And when glutamine was added to broth during fermentations with the mutant and initial strain, their yields were increased by14.1%and17.3%respectively. The mutant’s yield was stable after preservation three weeks and subculturing three times.During the fermentation of Streptomyces lincolnensis, adding alanine and trimethylamine, the yield of lincomycin was increased by25%. By measuring several important enzymatic activities and amounts of precursors, it was found that the addition of0.01%alanine at the beginning of fermentation could restrain the enzymatic activity of pyruvate kinase to increase the amount of PEP. And the addition of0.02%trimethylamine at24h of fermentation could restrain the enzymatic activity of anthranilate synthase to increase the amount of L-dopa. Finally, the amount of lincomycin was increased.The mutant P2-A6-P10-10and initial strain07-5were fermented in50L bio-reactors. Through the process improvement, mutant’s yield was increased by26.7%. Some fermentations parameters were measured during the fermentation, and it was found the mutant’s growth and synthesis metabolism were more exuberant than the initial strain’s.