| Biosurfactant producing strain was the premise and basis of industrial production of biosurfactant. As a new developed cell engineering technology in 1980s, cell electrofusion has become the preferred method in strain selection because of its unique advantage, which has been used widely in animal and plant cells breeding.However, there are also many shortcomings, such as microbial cells are smaller, but fusion electrode is larger, the action point is difficult to be controlled, and fusants are not easy to be screened and so on. These shortcomings limited the application of the electric fusion in microorganisms.To solve the problems mentioned above, the study has done some related research on cell electrofusion technique and electric screening of high-performance resistance fusant by using home-made microelectrode array chip cell power system as the experimental platform integration. The main conclusions are as follows:①Electroporation is the key link of the electrofusion process. Theoretical analysis from the penetration mechanism of electroporation, occurring conditions and models were studied. The influence of the electrical pulse parameters on the yeast protoplast electroporation was investigated, and the result indicated that perforated percentage increased with the pulse voltage, pulse duration and pulse number's increase. When the pulse voltage was 40V, pulse duration was 10μs, and pulse number was 8 with 87% perforated percentage attained.The influence of the electrical pulse parameters, calcium and magnesium concetration on electrofusion was investigated, and the yeast protoplast electrofusion conditions were optimizedand to get the best fusion conditions: pulse voltage of 60V, the number of 11 pulses, pulse duration 80μs, calcium concentration 0.05mmol/L and magnesium concentration 0.1mmol/L of plasma mixture, and the highest fusion rate was 16%. When yeast protoplasts were stained by Rhodamine B and the FDA, and then fused, the expected integration of sub-yellow was observed.A penicillin resistant strain of BSA-5 and a kanamycin resistant strain of BSK-6 were obtained by using UV-induced mutation. The surface tension of BSA-5 was 42.81 mN/M, emulsifying capacity was 93.7%. The surface tension of BSK-6 was 43.20 mN/M, emulsifying capacity was 88.4%. Then, both the protoplast before and after the UV-induced were cultured furtherly. We investigated the influence of a fluorescent dye on protoplast regeneration and its surfactant properties through the determination of dilution, plate colony counting, oil spreading, surface tension and emulsifying power. BSA-5 strain regeneration rate increased by 0.2% than the original strain while BSK-6 strain regeneration rate was lower than the original strain of 0.3%. As for surface activity, compared with the mutant resistant strain and the original strains, surface activity was in great deviation at the beginning, but after 4-5 days'culture, it's gradually close to the original strain; the emulsifying power of mutation resistant strain always maintained similar with the original strain.Under the condition of the sorbitol concentration of 0.8mol / L, pulse voltage of 60V, pulse number 11, a pulse duration of 80μs, and the mixture of 0.05mmol/LCa2 + and 0.1mmol/LMg2 + ions ,we fused BSA-5 and BSK-6 protoplasts, and screened out a high-performance surfactant producing bacteria, whose surface tension was 34.13 mN/M and emulsifying power increased from 89.3% of the original strain to 98%.
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