pAMβ1-Associated Mobilization of Proteinase Plasmids from Lactococcus lactis subsp. lactis UC317 and L. lactis subsp. cremoris UC205

Abstract

A combination of plasmid curing and DNA-DNA hybridization data facilitated the identification of proteinase plasmids of 75 (pCI301) and 35 kilobases (pCI203) in the multi-plasmid-containing strains Lactococcus lactis subsp. lactis UC317 and L. lactis subsp. cremoris UC205, respectively. Both plasmids were transferred by conjugation to a plasmid-free background only after introduction of the conjugative streptococcal plasmid, pAMW1. All Prt+ transconjugants from matings involving either donor contained enlarged recombinant Prt plasmids. UC317-derived transconjugants were separable into different classes based on the presence of differently sized cointegrate plasmids and on segregation of the pCI301-derived Lac and Prt markers. All UC205-derived transconjugants harbored a single enlarged plasmid that was a cointegrate between pCI203 and pAM01. The identification of prt genes on pCI301 and pCI203 derivatives was achieved * Corresponding author. has been reported; pAMpl-mediated transfer of the bacte

Identification of the Minimal Replicon of Lactococcus lactis subsp. lactis UC317 Plasmid pCI305

“…lactis UC317 harbors five plasmids (Fig. 1, lane 1), the largest of which, pCI301 (75 kb), encodes Lac Prt (22). The smallest cryptic plasmid in UC317, pCI305 (8.7 kb), was particularly stable under conditions such as protoplasting and regeneration or growth in the presence of plasmid-curing agents, which successfully cured all other plasmids from this strain.…”

“…Rapid preparation of plasmid DNA from lactococcal strains was by the method of Anderson and McKay (1). Plasmid profiles were analyzed as described in the accompanying report (22). Purified plasmid DNA was isolated from lactococci as described by Anderson and McKay (1) and was further treated as outlined elsewhere (22).…”

“…Plasmid profiles were analyzed as described in the accompanying report (22). Purified plasmid DNA was isolated from lactococci as described by Anderson and McKay (1) and was further treated as outlined elsewhere (22). Preparative amounts of plasmid DNA were isolated from E. coli as outlined by Birnboim and Doly (4) followed by CsCl-ethidium bromide density gradient ultracentrifugation.…”

“…A scaled-down version of this procedure was also used in rapid screening and restriction analysis of DNA from E. coli clones, except that the lysozyme treatment and phenol-chloroform and chloroform extraction steps were omitted. Restriction endonuclease digestions of plasmid DNA were analyzed as described elsewhere (22). Restriction endonucleases, calf intestinal alkaline phosphatase, Klenow fragment of DNA polymerase I, and T4 DNA ligase were supplied by the Boehringer Corporation Ltd., Dublin, Ireland, and were used as recommended by the manufacturer.…”

Cytotoxic Effect of the Locally Isolate Lactococcus lactis Cell Wall Proteins on Tumor Cell Lines

“…Depending on the results of the cultural and microscopic tests, nine isolates may be belonging to the genus Lactococcus referred to as (Lc1, Lc2, Lc3, Lc4, Lc5, Lc6, Lc7, Lc8 and Lc9) and the other tested isolates may be belonging to the genus Lactobacillus. The abundance of the genus Lactococcus in dairy and dairy products is reasonable because they possesses proteinase enzyme system encourage them to grow in milk and its products [17].…”