In Vivo Cloning of lac Genes in Streptococcus lactis ML3 †
AUTOR(ES)
Anderson, Douglas G.
RESUMO
The isolation and characterization of a Streptococcus lactis ML3 strain which possessed a recombinant lactose plasmid is described. The recombination events generating this plasmid occurred in vivo in a recombination-deficient strain and appeared to be mediated by transposition events. Restriction mapping revealed that the recombinant plasmid, pDA0307, contained a region of the lactose plasmid, pSK08, linked to another resident plasmid, pSK07. Copy number determinations indicated that the lac genes were present at approximately 20 copies per cell in pDA0307, whereas the lac genes are normally present at approximately 10 copies per cell in pSK08. The strain containing pDA0307 displayed a 21 to 54% increase in the expression of the Lac enzyme phospho-β-d-galactosidase. However, the strain containing pDA0307 both grew and produced lactic acid in milk at rates identical to that of a strain containing pSK08. This result suggests that lac gene dosage of plasmid-linked lac genes was not limiting the rate at which these derivatives of S. lactis ML3 fermented milk.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=239652Documentos Relacionados
- Method for Growth and Purification of Bacteriophage 643 on Streptococcus lactis ML3
- Restriction endonuclease analysis of the lactose plasmid in Streptococcus lactis ML3 and two recombinant lactose plasmids.
- Plasmid Profiles of Lactose-Negative and Proteinase-Deficient Mutants of Streptococcus lactis C10, ML3, and M18 †
- Isolation of a recombination-deficient mutant of Streptococcus lactis ML3.
- Recombinant plasmid associated cell aggregation and high-frequency conjugation of Streptococcus lactis ML3.
