Study On The Breeding Of Micronomicin-producing Strain With Higher-yield

Micronomicin (MCR) is the C_2b component of Gentamicin. And it is an antimicrobial with low toxin to the ear and kidney, and is used widely in clinic. MCR is a new type antibiotic composed of amido-indican compound, and it will keep the active effect on the bacteria with antibiotic-resistant of acetylase. The strain 201-9^# is used to the starting strains in our experiment for its high productivity A and preponderant C_t, C₅ values.By inducing original Micromonospora purpura 201-9^# with microwave irradiation and resistance-MCR treatment, two stable mutants 201-9^#-28' and 201-9^#-95' were isolated. Their productivity have been increased 42.18% and 59.6% than that of the original strain, respectively.The methods and conditions of protoplast formation and regeneration have been systematic studied to strain 201-9^# . The results showed that the optimal techniques conditions of protoplast formation and regeneration are: after growing 48h ,10% of mycelia were inoculated to the growth medium, in which 0.3% Gly contained, then continued to grow 48h. Pretreatment be carried out for mycelia solution and lysozyme is added. The concentration of lysozyme used was 15 mg/ml, reaction at 37°C and 90 mins. Then the protoplasts solution were smeared to regenerative medium R2, in which the concentration of superstratum agar is 0.8%, incubated in double layer agar plate method.Based on the sensitive nature of protoplasts are higher than that of the spores. The experiments of combining protoplast regeneration with UV mutation have completed successfully. And the Micronomicin-producing mutants with high productivity and genetic stability have been isolated, one was mutant 201-9^#-465 with 57.1% bioactivity uphill and C_2b:C_1a=7:3, another was mutant 201-9^#-479 with 71.1% bioactivity increase and C_2b: C_1a=6.5:3.5.