Preliminary Sduties On Breeding And Metabolome Of Antifungal Antibiotic Producing Strains

In order to enhance the ability in producing antifungal antibiotic of Streptomyces lydicus AS 4.2501 which was obtained from soil by our laboratory , and accelerate the application of antifungal antibiotic in industry. The traditional mutagenesis method was executed to breed the Streptomyces lydicus AS 4.2501, and the intermediate metabolites produced during the process of Streptomyces lydicus fermentation in 2L fermentor were analyzed using the Gas Chromatography/Time-of-Flight Mass Spectrometry (GC/TOFMS) method. And the results are as follows:Applied Compound Mutagenesis of nitrous acid(HNO2) and ultraviolet radiation (UV) combined with strain-produced antibiotic resistance screening mutants, with Rhizoctonia solani as the indicator microorganism, we obtained a high-yield mutant E9. The relative biologic activity of the fermentation broth of the mutant E9 incresed 82.6%compared with the control. The cultivation and fermentation time of the mutant E9 is 24 hours less than control. The inheriting research showed that the mutant E9 had stable producing ability, and the relative biologic activity of the fermentation broth of the mutant E9 is very stable during the temperature range of -20℃~121℃. These characteristics of the mutant E9 are good for saving raw material and cutting producing cost in the process of producing antibiotic.The results of our research also showed that, the metabolic rate of mutant E9 fermented in 2L fermentor was also 24 hours faster than the control. The content of reductive sugar in the fermentation broth of the mutant E9 was much less than the control. So we conclude that reductive sugar may be the necessary substrate for the synthesis of the antifungal antibiotic. Further we used GC/TOFMS analyze the intracellular metabolites of the control and the mutant E9 respectively, compared the difference of intermediate metabolites yielded by the two strains respectively. 83 chromatographic peaks were detected, 23 substances were identified by NIST, these metabolites belonged to amino acid, carboxyl acid, sugar, sugar ethanol, phosphate compound, aroma compound, saturated and unsaturated fatty acid, nucleic acid, sterol and some other kinds of compounds. The intermediate metabolites in the control was much more than the mutant strainE9, especially after cultured for 36 h, the trend was more obvious. Through the principle component analysis(PCA) the metabolites profiling obtained by GC/TOFMS, we got two biomarkers, being glutamic acid and ethylene oxide respectively. Both substances could distinguish the high-productivity strain and the parental strain clearly.The results from this study was in favor of analyzing the metabolized mode of Streptomyces lydicus AS 4.2501 and the biosnythesis pathway of the antifungal antibiotic produced by Streptomyces lydicus AS 4.2501.