Study on breeding of high LI-F type antibiotics producing mutant strain of paenibacillus polymyxa JSa-9

In order to improve the yield of LI-F type antibiotics produced by Paenibacillus polymyxa JSa-9, three different methods including 1-methyl-3-nitro-1-nitroso-guanidin (NTG), ⁶⁰Co-γ rays and low energy N⁺ ion implantation were used for mutation of starting strain JSa-9. The optimal mutagenesis concentration of NTG and dose of ⁶⁰Co-γ ray were respectively identified as 50 μg·mL^-1 and 200 Gy. When the low energy N⁺ ion implantation energy were 10 keV or 20 keV, the optimal injection time were separately 60 and 30 s. By using of NTG mutation a phenylalanine auxotrophic strain N1-37 and a histidine auxotrophic strain N2-27 were ultimately screened out from 300 mutant strains. Staphylococcus aureus was used as a target strain for the inhibition experiment, the results showed that the inhibition zone diameters of strain N1-37 and N2-27 respectively increased 45.54% and 32.35% compared with starting strain JSa-9. By the methods of HPLC the yield of LI-F type antibiotics were determined. The results indicated that the yields of LI-F type antibiotics produced by strain N1-37 and strain N2-27 were respectively 1.71-fold and 1.4-fold of strain JSa-9. The two mutant strains were continuously subcultured for 10 generations and showed good genetic stability. The results obtained here showed strain N1-37 and N2-27 not only had the potential for industrial productions, but also could be used as the parent strains for the cell fusion research. (authors)