Application of the extracellular alpha-amylase gene from Streptococcus bovis 148 to construction of a secretion vector for yogurt starter strains

Article Abstract:

A genetic vector containing the alpha-amylase gene of Streptococcus bovis 148 was used to transform Streptococcus thermophilus ATCC 19528, Lactobacillus delbrueckii subsp. bulgaricus T-11 and Lactococcus lactis subsp. lactis IL1403. All transformed bacteria expressed alpha-amylase and secreted the enzyme. The success of the transformation experiment using the alpha-amylase expression elements has bearing in the transformation of starting strains in yogurt production.

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Use of glnQ as a counterselectable marker for creation of allelic exchange mutation in group B streptococci

Article Abstract:

A counterselectable marker is reported by using glnQ with gamma-glutamyl hydrazide (GGH) selection and is used to isolate mutant GBS strains that have the chromosomal capsular polysaccharide regulatory gene cpsB replaced by the chloramphenicol acetyltransferase (cat) gene. It was found that efficient allelic exchange mutagenesis in group B streptococci (GBS) was hampered by the lack of a counterselectable marker system.

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thyA as a selection marker in construction of food-grade host-vector and integration systems for Streptococcus thermophilus

Article Abstract:

Streptococcus thermophilus is one of the important lactic acid bacteria (LAB) and has long been used to produce yogurt and cheeses. A description of how spontaneous thymidylate synthase gene(thyA) mutants of Streptococcus thermophilus are obtained by using high concentrations of trimethoprim(TMP) is provided.

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