Studies On Apramycin-Producing Strain

Streptomyces tenebrarius A04, the producer (with a titer of 2874u/ml) of single component of nebramycin ?apramycin was studied in this paper. After treatment of spore suspension and mycelia shivered by supersonic with mutagen ,combined with the application of screening models, some stable high yield apramycin-producing strains (with a fermentation titer of 4800-5200u/ml by shaking flask) such as A2-23, A2-30, ASM6 and Al-16 were obtained.This result proved that UV treatment combined with tolerating apramycin or with tolerating streptomycin could be effective way to obtain high yield apramycin-producing strains.With strain Al-16, the fermentation medium, aeration and inoculation volume etc. were investigated and the optimized vegetative medium and fermentation medium were obtained by uniform design.The tertiary fermentation techniques and the FBC (fed-batch culture) and other fermentation techniques were also optimized. A scale-up fermentation technique was set up and the apramycin productivity reached 4478u/ml in a 4m3 fermentator.Amino acid feeding experiments were also performed in this study in order to investigate the pathway, by which nitrogen incoperated into apramycin molecule, and the regulatory mechanism of nitrogen metabolism.The feeding of glutamic acid, glutamine and a -keto- glutaric acid respectively showed that glutamic acid and glutamine had no obvious effectson cell growth , but stimulated apramycin production greatly.With the same concentration of amino acids supplemented ,glutamine showed a stronger stimulation effect than glutamic acid, while a -keto-glutaric acid showed a repression effect on apramycin production. It could be deduced from above results that glutamine possibly is the donor of nitrogen element for the biosynthesis of apramycin. Arginine feeding experiment showed that nitrogen metabolism in the S.tenebraius was obviously affected by arginine through two possible ways:(l)pronase activity in vitro could be influnced by arginine, as a result, the catabolism of nitrogen-containing macro-molecule was promoted and the nitrogen element in the broth was increased.(2)arginine could be transformed into glutamic acid, so that the biosynthesis of apramycin was promoted.