potential food-grade cloning vector for Streptococcus thermophilus that uses cadmium resistance as the selectable marker

• Published in: Applied and Environmental Microbiology Vol. 69; no. 10; pp. 5767 - 5771
• Main Authors: Wong, W.Y, Su, P, Allison, G.E, Liu, C.Q, Dunn, N.W
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.10.2003
• Subjects: Bacteria; Biological and medical sciences; cadmium; Cadmium - pharmacology; Cloning; Cloning, Molecular; Conjugation, Genetic; Deoxyribonucleic acid; DNA; Drug Resistance, Bacterial - genetics; Electroporation; food biotechnology; Food Industry - methods; Fundamental and applied biological sciences. Psychology; Genetic Markers; genetic transformation; Genetic Vectors; Genetics and Molecular Biology; Genotype & phenotype; industrial applications; lactic acid bacteria; Lactococcus lactis; Lactococcus lactis - drug effects; Lactococcus lactis - genetics; metal tolerance; Microbiology; Molecular Sequence Data; nucleotide sequences; plasmid vectors; Plasmids; replicon; Streptococcus - drug effects; Streptococcus - genetics; Streptococcus thermophilus; Transformation, Bacterial; Resistance; Streptococcaceae; Cadmium; Streptococcus salivarius subsp. thermophilus; Bacteria; Micrococcales; Foodstuff; Molecular cloning; Vector
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/AEM.69.10.5767-5771.2003

A potential food-grade cloning vector, pND919, was constructed and transformed into S. thermophilus ST3-1, a plasmid-free strain. The vector contains DNAs from two different food-approved organisms, Streptococcus thermophilus and Lactococcus lactis. The 5.0-kb pND919 is a derivative of the cloning vector pND918 (9.3 kb) and was constructed by deletion of the 4.3-kb region of pND918 which contained DNA from non-food-approved organisms. pND919 carries a heterologous native cadmium resistance selectable marker from L. lactis M71 and expresses the Cdr phenotype in S. thermophilus transformants. With the S. thermophilus replicon derived from the shuttle vector pND913, pND919 is able to replicate in the two S. thermophilus industrial strains tested, ST3-1 and ST4-1. Its relatively high retention rate in S. thermophilus further indicates its usefulness as a potential food-grade cloning vector. To our knowledge, this is the first report of a replicative potential food-grade vector for the industrially important organism S. thermophilus.