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pAMbeta1-Associated Mobilization of Proteinase Plasmids from Lactococcus lactis subsp. lactis UC317 and L. lactis
F Hayes1, E Caplice, A McSweeney
1Department of Food Microbiology and National Food Biotechnology Centre, University College, Cork, Ireland.
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, pAMbeta1. 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 pAMbeta1. The identification of prt genes on pCI301 and pCI203 derivatives was achieved by a combination of restriction enzyme and hybridization analyses.
Insights
Researchers identified proteinase plasmids (pCI301, pCI203) in Lactococcus lactis strains. These plasmids, when combined with pAMbeta1, formed enlarged recombinant plasmids in transconjugants, aiding in prt gene identification.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Lactococcus lactis strains UC317 and UC205 contain multiple plasmids.
- Proteinase activity in L. lactis is often plasmid-mediated.
Purpose of the Study:
- To identify and characterize proteinase plasmids in L. lactis strains UC317 and UC205.
- To investigate the transfer and recombination of these plasmids.
Main Methods:
- Plasmid curing and DNA-DNA hybridization were used for plasmid identification.
- Conjugation experiments were performed using the streptococcal plasmid pAMbeta1.
- Restriction enzyme and hybridization analyses were employed to characterize prt genes.
Main Results:
- Proteinase plasmids pCI301 (75 kb) and pCI203 (35 kb) were identified in UC317 and UC205, respectively.
- Conjugation required the presence of pAMbeta1, resulting in enlarged recombinant plasmids in transconjugants.
- Transconjugants showed variations in plasmid size and marker segregation, indicating cointegrate formation.
Conclusions:
- pCI301 and pCI203 harbor genes essential for proteinase production.
- pAMbeta1 facilitates the transfer and recombination of these proteinase plasmids.
- The study elucidates the genetic basis of proteinase activity in these L. lactis strains.
