ABSTRACT
A new approach has been elaborated for electrofusion of Erwinia chrysanthemi spheroplasts. The new approach consists of superimposition of high voltage impulses on the pellet of tightly contacting cells in the course of centrifugation. The mixture of spheroplasts of two genetically marked strains was placed into the special centrifuge chambers and spinned for 15 min at 2500 g to get a compressed pellet between chamber electrodes. Three successive pulses of 6.6 kv/cm amplitude and 30 microseconds duration were applied to spheroplast pellet during centrifugation. Fusion products were viable and after plating on the surface of hypertonic medium regenerated to the rod forms. As a result, the hybrid clones carrying the markers of both parents were isolated.
Subject(s)
Electricity , Erwinia/physiology , Spheroplasts/physiology , Bacteriological Techniques , Culture Media , Erwinia/genetics , Erwinia/radiation effects , Polyethylene Glycols/pharmacology , Recombination, Genetic , Spheroplasts/radiation effectsABSTRACT
Cells of 56 pectolytic Erwinia strains of different origin tested are prone to filamentation after UV-irradiation. The fact makes one possible to consider them natural fil+ organisms. Bacteria E. herbicola (9 strains) that are unable to synthesize pectatelyases are not transformed into filaments after NV-irradiation. The function of fil+ genes is recA-dependent in bacteria E. chrysanthemi ENA49 and is phenotypically analogous to fil+ gene function in E. coli B or lon- mutation in E. coli K12.
Subject(s)
Erwinia/radiation effects , Ultraviolet Rays , Erwinia/growth & development , Erwinia/ultrastructure , SOS Response, GeneticsABSTRACT
The effect of UV light and mitomycin C as inductors of bacteriocins biosynthesis by Erwinia was studied. 46 strains of Erwinia were tested and the synthesis of bacteriocins was induced by irradiation with UV light only in 14 of them. The irradiation dose providing the highest increase of the bacteriocin titer was different for every strain. The survival of the strains ranged within 0.06 to 11.3 per cent. The time course of the bacteriocin synthesis induced by UV light in 9 strains of Erwinia was studied and it was shown that the process had common similar characteristics: gradual increasing of the bacteriocin titer immediately after exposure to UV light, reaching the maximum level 5-7 hours after incubation and its persisting for the subsequent observation period. Mitomycin indices bacteriocin production by the Erwinia strains tested only in individual cases, the character of the effect being dependent on the drug concentration and exposure time.
