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Werning ML,
Ibarburu I,
Dueñas MT,
Irastorza A,
Navas J,
López P,
( 2006 ) Pediococcus parvulus gtf gene encoding the GTF glycosyltransferase and its application for specific PCR detection of beta-D-glucan-producing bacteria in foods and beverages. PMID : 16416914 : DOI : 10.4315/0362-028x-69.1.161 Abstract >>
Exopolysaccharide production by lactic acid bacteria is beneficial in the dairy and oat-based food industries and is used to improve the texture of the fermented products. However, beta-D-glucan-producing bacteria are considered spoilage microorganisms in alcoholic beverages because their secreted exopolysaccharides alter the viscosity of cider, wine, and beer, rendering them unpalatable. The plasmidic glycosyltransferase (gtf) gene of the Pediococcus parvulus 2.6 strain isolated from ropy cider has been cloned and sequenced, and its GTF product was functionally expressed in Streptococcus pneumoniae. The GTF protein, which has glycosyltransferase activity, belongs to the COG1215 membrane-bound glycosyltransferase family, and agglutination tests revealed that the enzyme enables S. pneumoniae to synthesize beta-D-glucan. PCR amplification and Southern blot hybridization showed that the gtf gene is also present at different genomic locations in the beta-D-glucan producers Lactobacillus diolivorans G77 and Oenococcus oeni I4 strains, also isolated from ropy cider. A PCR assay has been developed for the detection of exopolysaccharide-producing bacteria. Forward and reverse primers, included respectively in the coding sequences of the putative glycosyltransferase domain and the fifth trans-membrane segment of the GTF, were designed. Analysis of 76 ropy and nonropy lactic acid bacteria validated the method for specific detection of beta-D-glucan homopolysaccharide producer Pediococcus, Lactobacillus, and Oenococcus strains. The limit of the assay in cider was 3 X 10(2) CFU/ml. This molecular method can be useful for the detection of ropy bacteria in cider before spoilage occurs, as well as for isolation of new exopolysaccharide-producing strains of industrial interest.
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2. |
Naser SM,
Dawyndt P,
Hoste B,
Gevers D,
Vandemeulebroecke K,
Cleenwerck I,
Vancanneyt M,
Swings J,
( 2007 ) Identification of lactobacilli by pheS and rpoA gene sequence analyses. PMID : 18048724 : DOI : 10.1099/ijs.0.64711-0 Abstract >>
The aim of this study was to evaluate the use of the phenylalanyl-tRNA synthase alpha subunit (pheS) and the RNA polymerase alpha subunit (rpoA) partial gene sequences for species identification of members of the genus Lactobacillus. Two hundred and one strains representing the 98 species and 17 subspecies were examined. The pheS gene sequence analysis provided an interspecies gap, which in most cases exceeded 10 % divergence, and an intraspecies variation of up to 3 %. The rpoA gene sequences revealed a somewhat lower resolution, with an interspecies gap normally exceeding 5 % and an intraspecies variation of up to 2 %. The combined use of pheS and rpoA gene sequences offers a reliable identification system for nearly all species of the genus Lactobacillus. The pheS and rpoA gene sequences provide a powerful tool for the detection of potential novel Lactobacillus species and synonymous taxa. In conclusion, the pheS and rpoA gene sequences can be used as alternative genomic markers to 16S rRNA gene sequences and have a higher discriminatory power for reliable identification of species of the genus Lactobacillus.
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