Research On The Process Optimization Of Erythromycin Fermentation

Erythromycin is a macrolide antibiotic fermentated from the Streptomyces andfound to have broad spectrum antibacterial activity. The erythromycin majorantibacterial activity against Gram-positive bacteria is one of the clinically usedantibiotics. Thus increasing the content of erythromycin in the fermentation brothhas a very important significance.The erythromycin Streptomyces strain mutagenesis by UV， lithium chlorideand the microwave. These three mutation methods achieved the intended purpose:mutagenesis out W-12, which has a good genetic stability and the potency increasedby11.0%compared to original strain. This step has laid a good foundation forfurther shake-flask culture medium optimization.On the basis of the mutant strain, the erythromycin fermentation medium andculture conditions were optimized.1. The absorption and utilization of nutrients to mutant strains were investigatedby shake flask experiments. From the results, glucose and soluble starch are the bestcomposite carbon source. We choose soybean powder as organic nitrogen, which ismore cheap and easy to get. Considering inorganic nitrogen sources, ammoniumsulfate easier to utilize by bacteria, and is conducive to the biosynthesis oferythromycin.2. Orthogonal test was used for a best medium, the main component of theoptimal medium composed of3.0%of soybean flour,0.5%glucose,2.0%solublestarch, ammonium sulfate0.30%, magnesium sulfate0.20%. After mediumoptimization, the potency increased by13.4%compared to control group. Last,experimental results show that50mL medium was added to0.6mL soybean oil.3. Shake flask experiments to optimize the erythromycin overproducing strainfermentation conditions. The experiments show that,50mL/250mL of liquidvolume, inoculated with10%, pH value of6.7, the culture temperature of32℃is theoptimum fermentation conditions. Through a series of optimization, erythromycin titer increased13.4%and the Ccomponent content decreased from15.0%to3.1%.