Mutantion Breeding And Fermentation Condition Optimization Of Penicillin G High-yielding Strain

According to biosynthesis and metabolic regulation mechanism of penicillin G, the penicillin G producing strain, LN21, was optimized by induction of mutation and selection in order to obtain high-yield strains for industrial productuion. Base on the fermentation conditions in the original process, the culture conditions and fermentation conditions of high strain were optimized,in order to find the conditions for high-yield strains. Preparation of rice spores was studied.Using naturual selection, strain LN2148 which of five high-yielding strains was selected from culture preserved in LN21 sand pipe. The results showed that strain LN2148 had a good genetic stability, its colony purity was about 98.3%, and the fermentation titer was about 21,000U/mL. Using single factor experiments, the medium compositions was optimized, and the slant culture-medium, seed medium, and fermentation medium were determined.Using 4 times UV mutagenesis, an acid-resistant mutant strain LN214832 was obtained from strain LN2148. The results showed that the fermentation titer of this mutant strain increased 19.2% to 24032U/mL. The effects of ramp cycle, unit mycelium synthesis, seed culture time, quantity of precursor acid, and magnesium sulfate dosage on the mutant strains of LN214832 were studied. The results showed that, in mutant strain, the slope cycle was significantly increased to one day, the output of unit of mycelium was higher than original strain with transplanting time moved ahead of time 2h, the fermentation titer was significantly increased by adding 0.2% magnesium sulfate, and the fermentation titer was increased by 9.4% with acid concentration increased by 3%.Using protoplast fusion of LN214832 and another character entirely different strain LR208, sixteen fusants whose fermentation titers were 20% higher than LN214832 were selected. After another screening, LN21-R-48 whose fermentation titers was 25% higher than LN214832 and 28% higher than LR208 was obtained. The results showed that its fermentation titers reached 31,000U/mL. The effects of types of enzymes, mycelium culture time, hydrolysis temperature, enzyme dosage, and enzymatic digestion on the release rate of protoplast were studied. The results showed that its release speed of Novozyme 234 enzyme was better; protoplast release was the maximum after mycelia culturing of 48 h; protoplast release and regeneration frequency were higer when temperature reached 30℃; mycelial was digusted completely when mycelial enzyme was 150 mg/g, and enzyme was better after 3 h.The culture conditions of high strain LN21-R-48 were optimized in this papers, culture conditions of strain LN21-R-48 was determined,and the PH of initial seed culture medium was 6.0, seed culture temperature was between25℃and 28℃,age was between 42 h and 48 h.The effects of colony morphology, colony culture time, productivity, types of the parent rice and millet modulation methods on the sporulation and germination rate in the different situations were studied. At the last time, the culture vesse, load and water were changed in this papers,and the effects of sporulation, germination and other aspects of seed quality were studied. The results showed that the best culturing time of strain LN21-R-48 was nine days in the current culture conditions,at the same time, the whole colony morphology was better and average production capacity was the highest; rice pores grew well and mature spore color was gray green, and spore germination rate and capacity reached good level when water weighted by 32% with 250mL flask volume50g;the buffering capacity of outside humidity was stronger when used 500mL flask,to make them obtain industry production, sub-dwarf rice prepared with 2000mL fat bottle was better.