Genetic recombination by spheroplast fusion in Escherichia coli K12
Reina, S.; Debbia, E.A.; Schito, G.C.
Cytobios 76(305): 91-95
1993
ISSN/ISBN: 0011-4529 PMID: 8293682 Document Number: 406000
Genetic transfer mediated by spheroplast formation and fusion in Escherichia coli was studied. Recombination did not occur from spheroplasts prepared by the combined glycine and lysozyme-EDTA treatment described by Coetzee et al. (1979). In contrast, when bacteria were exposed to a sub-inhibitory concentration of polymyxin B (0.5 microgram/ml) during the spheroplast generation phase, recombinants arose at frequencies of 1 x 10(-8) to 2.6 x 10(-8). The incidence of genetic transfer was further increased by adding 0.01 M CaCl2 to the polyethylene glycol fusion mixture (from 9 x 10(-7) to 9 x 10(-8). Finally, when the effects of both polymyxin B and calcium chloride were combined recombinants arose at frequencies of 3.4 x 10(-6) to 7.3 x 10(-7). These findings suggest that the detergent-like action of polymyxin B in removing a large part of the outer membrane enhances plasma membrane availability where fusion can take place.