Study On Antibiotic-producing Instability And Selection Of High Producing Strains Of Actinomadura Yumaensis

Actinomadura yitmaense, the maduramicin producing strain has antibiotic -producing instability, which affects its industrial application. The study on the antibiotic-producing instability of Actinomaduara yumaense, the selection of Maduramin high production strains and optimization of the fermentation technics were carried out respectively.Mutants FS-11, FS-12, FS-13, FS-18, FS-19 and SS-1 were obtained with A. yumaense as the starting strain. Their life cycles and characteristics of their colonies were observed and strain S-l was found to have the typically morphological differentiation of A. yumaense. The morphological differences of every mutants and the period of morphological block were ascertained. After the fermentation experiments on the level of flask, the fundamental properties and the abilities to produce maduramicin of every mutant were acquired. Mutants FS-11 and FS-12 were high production strains while FS-18 and FS-19 totally lost the ability to produce maduramicin. After antibiotic resistance detection of strains S-l, FS-11, FS-13, FS-19 and SS-1, A. yumaense was found to be sensitive to erythromycin and chloramphenicol while it was resistant to Ampicillin, Maduramicin and Streptomycin. The higher the antibiotic productivity was, the stronger their resistance of the mutants to streptomycin was. It was indicated that the antibiotic productivity of the mutants was in positive correlation with their resistance to Streptomycin. The antiseptic activities of every strain were also detected. It was found out that Maduramicin production strains had strong antiseptic activities against G+ bacteria while Maduramicin non-producing strains had no antiseptic activities. No new antibiotics proved to be produced by the result. The restoration of Maduramicin production ability of FS-19 was tried and no antiseptic activity was attested. Through the above study, the antibiotic-producing instability of Actinomadura yumaense was fundamentally known and the direct reasons were not certain.The strain selection based on resistance to Streptomycin was carried out with Actinomadura yumaense S-l as the starting strain and 223 strains were chosen. After the primary and secondary selection, 7 strains were tested to have higher productivity than the starting strain. Of the 7 strains, strains S1-007, S1-123 and S1-018 were proved to produce more Maduramicin than the starting strain. Compared with 6236ug/ml of the starting strain, the productivity of the above three strains reached 8020 g/ml, 8254 g/mland9175 g/ml respectively. The productivity of strain S1-018 was improved 47%. The properties of high productivity of the three strains were proved to be stable after 5 continual progeny tests.Fermentation experiments on the level of 5L, 20L and 80L jars were carried out. The inceptive glucose condensation was kept and controlled below 1% through the supply of glucose during the fermentation period. The productivity was improved 40% compared with the common fermentation technics after the optimization.