Influence of lipopolysaccharide and protein in the cell envelope on recipient capacity in conjugation of Salmonella typhimurium

Abstract

In crosses of Salmonella typhimurium FfinP301 lac+ to F- strains of S. typhimurium in broth, recipient strains which were rough mutants affected in the outer core region of the lipopolysaccharide gave an average of 1.4 Lac+ transconjugants per donor cell and over 50% of the donor and recipient cells in mating aggregates, whereas smooth recipient strains gave 0.08 Lac+ transconjugants and few cells in mating aggregates. Strains with mutations affecting the inner core of the lipopolysaccharide were usually poor recipients. When cells were mated on Millipore membrane filters, both smooth and rough strains gave ca. 1.0 Lac+ transconjugants per donor cell. Plasmids in Inc groups FI, FII, M, J, and I beta gave more transconjugants with rough than smooth strains, but there were no difference in crosses with plasmids in Inc groups T, L, P, N, and W. Strains with mutations in the ompA gene (deficient in Omp Ap = 33K = II* = conjugation protein) yielded only 0.02 Lac+ transconjugants per donor cell and few cells in mating aggregates. There was no indication of a deficiency of Omp Ap in smooth strains compared with rough strains. Reduced fertility of smooth recipients may occur because the O side chains of the lipopolysaccharide shield the recipient and reduce the frequency of stabilization of mating aggregates. However, gradient-of-transmission experiments indicated that once these mating aggregates are stabilized, they are equally stable in both smooth and rough recipients. Fertility was high in crosses of S. typhimurium Flac+ to Escherichia coli K-12 F- (0.75 Lac+ transconjugants per donor cell; over 50% of the cells in mating aggregates). In crosses of E. coli K-12 Flac+ to S. typhimurium smooth F-, ca. 10(-5) Lac+ transconjugants per donor cell were obtained; in crosses to rough recipient strains, fertility was increased 14-fold, and when the recipient was defective in the SA and LT host restriction systems, fertility was increased in additional 100-fold. Thus, both the lipopolysaccharide and the protein in the cell envelope of S. typhimurium were shown to be important in the recipient function in F-mediated conjugation.

Identification of host genes that affect acquisition of an integrative and conjugative element in Bacillus subtilis

“…For example, in Enterococcus faecalis, potential recipients secrete signalling peptides that induce conjugation of certain plasmids (Dunny et al, 1978;Dunny, 2013). Studies with Escherichia coli, Salmonella typhimurium and E. faecalis identified surface components of the recipient that facilitate formation of mating pairs and contribute to conjugation (Watanabe et al, 1970;Skurray et al, 1974;Havekes et al, 1977;Sanderson et al, 1981;Trotter and Dunny, 1990;Ishiwa and Komano, 2004;Perez-Mendoza and de la Cruz, 2009).…”

A method for the enumeration of male‐specific bacteriophages in sewage

“…Van Leeuwen pers.comm.). The F'-plasmid in strain SA2197 was derepressed with regard to fertility inhibition by the pSLT plasmid resident in LT2-strains (Sanderson et al 1981).…”

“…Model experiments have shown that group E phages are capable of surviving well in water and sewage treatment processes (Ayres 1977) and that they are relatively resistant to inactivation by disinfectants (Shah & McCamish 1972;Snead el a!. 1980), heat treatment (Burge et ul.…”

Dynamics of the IncW genetic backbone imply general trends in conjugative plasmid evolution

“…The genetic organization of mobile DNA elements such as plasmids and bacteriophages differs from the chromosomal Bradley & Cohen (1976), Sanderson et al (1981), Gotz et al (1996) Ernstsson et al (2003) organization of their hosts. Plasmid organization, reviewed in detail by Thomas (2000), is based on the confluence and clustering of different survival and propagation functions, arranged in functional modules.…”