Influence of lactococcal plasmid on the specific growth rate of host cells

Lett Appl Microbiol. 2002;35(5):403-8. doi: 10.1046/j.1472-765x.2002.01213.x.

Abstract

Aims: To investigate a lactococcal plasmid responsible for a reduction in growth rate of its host cell.

Methods and results: Lactococcus lactis subsp. lactis biovar. diacetylactis DRC1 carries a high number of plasmids. The DRC1 wild-type strain was found to grow more slowly than a plasmid-free derivative of DRC1. The plasmids extracted from DRC1 together with an indicator plasmid were cotransformed into the plasmid-free strain DRC1021. A 7.4-kb cryptic plasmid, designated pDR1-1, was found to significantly affect the maximum specific growth rate ( micro max) of the host cell. Polymerase chain reaction (PCR) analysis was carried out in order to detect the presence of pDR1-1 in the other L. lactis strains. The micro max of the single pDR1-1-positive strain was determined to be the same as that of DRC1.

Significance and impact of the study: These results suggest that pDR1-1 (or a pDR1-1-like plasmid) is a critical factor in the reduction of the micro max of DRC1, and that its effect on the micro max is significantly greater than that of any other coexisting plasmid.

Publication types

  • Comparative Study

MeSH terms

  • Fermentation / genetics
  • Lactococcus lactis / genetics*
  • Lactococcus lactis / growth & development
  • Lactococcus lactis / metabolism
  • Molecular Sequence Data
  • Mutation
  • Open Reading Frames
  • Plasmids / analysis
  • Plasmids / genetics*
  • Polymerase Chain Reaction / methods
  • Time Factors