Cloning of genes encoding colicin E2 in Lactococcus lactis subspecies lactis and evaluation of the colicin-producing transformants as inhibitors of Escherichia coli O157:H7 during milk fermentation

S. M. Liu, D. M. Miller, Robert F. Roberts

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2 Citations (Scopus)

Abstract

Colicin E2 (ColE2) is a proteinaceous bacterial toxin produced by some strains of Escherichia coli and other members of the Enterobacteriaceae that exhibits inhibitory activity against some strains of E. coli O157:H7. A 2.0-kb DNA fragment, containing the ColE2 structural gene ceaB and immunity gene ceiB from E. coli NCTC 50133 (pColE2-P9), was cloned into the lactococcal plasmid vector pNZ2103. The lysis gene, celB, was not cloned. The plasmid, pLR-E2, encoding the cloned genes was transformed into E. coli DH5α and Lactococcus lactis ssp. lactis LM0230 and PN-1 using electroporation. The bacteriocin ColE2 was expressed in transformants of both E. coli and L. lactis ssp. lactis. Secretion of ColE2 into media was verified by spot-on-lawn assays and measurement of ColE2 activity in the growth medium of transformants. The level of ColE2 produced by transformants containing pLR-E2 was similar to that produced by the parental strain, E. coli NCTC 50133 (pColE2-P9). Evaluation of a ColE2-producing transformant of L. lactis ssp. lactis as a starter culture revealed that, although ColE2 was produced by transformants and could be detected in milk during fermentation, the inhibitory activity of ColE2 against E. coli O157:H7 was significantly decreased in milk compared with buffered growth medium.

Original languageEnglish (US)
Pages (from-to)1146-1154
Number of pages9
JournalJournal of dairy science
Volume94
Issue number3
DOIs
StatePublished - Mar 1 2011

Fingerprint

colicins
Colicins
Lactococcus lactis
Escherichia coli O157
Fermentation
Organism Cloning
molecular cloning
Milk
fermentation
milk
Genes
Escherichia coli
Plasmids
culture media
bacterial toxins
Bacterial Toxins
plasmid vectors
Bacteriocins
Electroporation
electroporation

All Science Journal Classification (ASJC) codes

  • Food Science
  • Animal Science and Zoology
  • Genetics

Cite this

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title = "Cloning of genes encoding colicin E2 in Lactococcus lactis subspecies lactis and evaluation of the colicin-producing transformants as inhibitors of Escherichia coli O157:H7 during milk fermentation",
abstract = "Colicin E2 (ColE2) is a proteinaceous bacterial toxin produced by some strains of Escherichia coli and other members of the Enterobacteriaceae that exhibits inhibitory activity against some strains of E. coli O157:H7. A 2.0-kb DNA fragment, containing the ColE2 structural gene ceaB and immunity gene ceiB from E. coli NCTC 50133 (pColE2-P9), was cloned into the lactococcal plasmid vector pNZ2103. The lysis gene, celB, was not cloned. The plasmid, pLR-E2, encoding the cloned genes was transformed into E. coli DH5α and Lactococcus lactis ssp. lactis LM0230 and PN-1 using electroporation. The bacteriocin ColE2 was expressed in transformants of both E. coli and L. lactis ssp. lactis. Secretion of ColE2 into media was verified by spot-on-lawn assays and measurement of ColE2 activity in the growth medium of transformants. The level of ColE2 produced by transformants containing pLR-E2 was similar to that produced by the parental strain, E. coli NCTC 50133 (pColE2-P9). Evaluation of a ColE2-producing transformant of L. lactis ssp. lactis as a starter culture revealed that, although ColE2 was produced by transformants and could be detected in milk during fermentation, the inhibitory activity of ColE2 against E. coli O157:H7 was significantly decreased in milk compared with buffered growth medium.",
author = "Liu, {S. M.} and Miller, {D. M.} and Roberts, {Robert F.}",
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T1 - Cloning of genes encoding colicin E2 in Lactococcus lactis subspecies lactis and evaluation of the colicin-producing transformants as inhibitors of Escherichia coli O157:H7 during milk fermentation

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AU - Miller, D. M.

AU - Roberts, Robert F.

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N2 - Colicin E2 (ColE2) is a proteinaceous bacterial toxin produced by some strains of Escherichia coli and other members of the Enterobacteriaceae that exhibits inhibitory activity against some strains of E. coli O157:H7. A 2.0-kb DNA fragment, containing the ColE2 structural gene ceaB and immunity gene ceiB from E. coli NCTC 50133 (pColE2-P9), was cloned into the lactococcal plasmid vector pNZ2103. The lysis gene, celB, was not cloned. The plasmid, pLR-E2, encoding the cloned genes was transformed into E. coli DH5α and Lactococcus lactis ssp. lactis LM0230 and PN-1 using electroporation. The bacteriocin ColE2 was expressed in transformants of both E. coli and L. lactis ssp. lactis. Secretion of ColE2 into media was verified by spot-on-lawn assays and measurement of ColE2 activity in the growth medium of transformants. The level of ColE2 produced by transformants containing pLR-E2 was similar to that produced by the parental strain, E. coli NCTC 50133 (pColE2-P9). Evaluation of a ColE2-producing transformant of L. lactis ssp. lactis as a starter culture revealed that, although ColE2 was produced by transformants and could be detected in milk during fermentation, the inhibitory activity of ColE2 against E. coli O157:H7 was significantly decreased in milk compared with buffered growth medium.

AB - Colicin E2 (ColE2) is a proteinaceous bacterial toxin produced by some strains of Escherichia coli and other members of the Enterobacteriaceae that exhibits inhibitory activity against some strains of E. coli O157:H7. A 2.0-kb DNA fragment, containing the ColE2 structural gene ceaB and immunity gene ceiB from E. coli NCTC 50133 (pColE2-P9), was cloned into the lactococcal plasmid vector pNZ2103. The lysis gene, celB, was not cloned. The plasmid, pLR-E2, encoding the cloned genes was transformed into E. coli DH5α and Lactococcus lactis ssp. lactis LM0230 and PN-1 using electroporation. The bacteriocin ColE2 was expressed in transformants of both E. coli and L. lactis ssp. lactis. Secretion of ColE2 into media was verified by spot-on-lawn assays and measurement of ColE2 activity in the growth medium of transformants. The level of ColE2 produced by transformants containing pLR-E2 was similar to that produced by the parental strain, E. coli NCTC 50133 (pColE2-P9). Evaluation of a ColE2-producing transformant of L. lactis ssp. lactis as a starter culture revealed that, although ColE2 was produced by transformants and could be detected in milk during fermentation, the inhibitory activity of ColE2 against E. coli O157:H7 was significantly decreased in milk compared with buffered growth medium.

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