1. |
Scheirlinck I,
Van der Meulen R,
Van Schoor A,
Vancanneyt M,
De Vuyst L,
Vandamme P,
Huys G,
( 2007 ) Influence of geographical origin and flour type on diversity of lactic acid bacteria in traditional Belgian sourdoughs. PMID : 17675431 : DOI : 10.1128/AEM.00894-07 PMC : PMC2075033 Abstract >>
A culture-based approach was used to investigate the diversity of lactic acid bacteria (LAB) in Belgian traditional sourdoughs and to assess the influence of flour type, bakery environment, geographical origin, and technological characteristics on the taxonomic composition of these LAB communities. For this purpose, a total of 714 LAB from 21 sourdoughs sampled at 11 artisan bakeries throughout Belgium were subjected to a polyphasic identification approach. The microbial composition of the traditional sourdoughs was characterized by bacteriological culture in combination with genotypic identification methods, including repetitive element sequence-based PCR fingerprinting and phenylalanyl-tRNA synthase (pheS) gene sequence analysis. LAB from Belgian sourdoughs belonged to the genera Lactobacillus, Pediococcus, Leuconostoc, Weissella, and Enterococcus, with the heterofermentative species Lactobacillus paralimentarius, Lactobacillus sanfranciscensis, Lactobacillus plantarum, and Lactobacillus pontis as the most frequently isolated taxa. Statistical analysis of the identification data indicated that the microbial composition of the sourdoughs is mainly affected by the bakery environment rather than the flour type (wheat, rye, spelt, or a mixture of these) used. In conclusion, the polyphasic approach, based on rapid genotypic screening and high-resolution, sequence-dependent identification, proved to be a powerful tool for studying the LAB diversity in traditional fermented foods such as sourdough.
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2. |
Scheirlinck I,
Van der Meulen R,
Van Schoor A,
Cleenwerck I,
Huys G,
Vandamme P,
De Vuyst L,
Vancanneyt M,
( 2007 ) Lactobacillus namurensis sp. nov., isolated from a traditional Belgian sourdough. PMID : 17267954 : DOI : 10.1099/ijs.0.64607-0 DOI : 10.1099/ijs.0.64607-0 Abstract >>
A biodiversity study on lactic acid bacteria (LAB) occurring in traditional Belgian sourdoughs resulted in the isolation of two Lactobacillus isolates, LMG 23583T and LMG 23584, that could not be assigned to any recognized LAB species. The two isolates were initially investigated by means of phenylalanyl-tRNA synthase (pheS) gene sequence analysis and were found to occupy a separate position relative to recognized Lactobacillus species present in the pheS database. Subsequently, their phylogenetic affiliation was determined by 16S rRNA gene sequence analysis, indicating that the two isolates belong to the Lactobacillus buchneri species group with Lactobacillus zymae, Lactobacillus acidifarinae and Lactobacillus spicheri as closest relatives. Whole-cell protein analysis (SDS-PAGE) and amplified fragment length polymorphism fingerprinting of whole genomes confirmed their separate taxonomic status. DNA-DNA hybridization experiments, DNA G+C content, growth characteristics and biochemical features demonstrated that the two isolates represent a novel Lactobacillus species, for which the name Lactobacillus namurensis sp. nov. is proposed. The type strain is LMG 23583T (=CCUG 52843T).
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3. |
Scheirlinck I,
Van der Meulen R,
Van Schoor A,
Vancanneyt M,
De Vuyst L,
Vandamme P,
Huys G,
( 2008 ) Taxonomic structure and stability of the bacterial community in belgian sourdough ecosystems as assessed by culture and population fingerprinting. PMID : 18310426 : DOI : 10.1128/AEM.02771-07 PMC : PMC2293155 Abstract >>
A total of 39 traditional sourdoughs were sampled at 11 bakeries located throughout Belgium which were visited twice with a 1-year interval. The taxonomic structure and stability of the bacterial communities occurring in these traditional sourdoughs were assessed using both culture-dependent and culture-independent methods. A total of 1,194 potential lactic acid bacterium (LAB) isolates were tentatively grouped and identified by repetitive element sequence-based PCR, followed by sequence-based identification using 16S rRNA and pheS genes from a selection of genotypically unique LAB isolates. In parallel, all samples were analyzed by denaturing gradient gel electrophoresis (DGGE) of V3-16S rRNA gene amplicons. In addition, extensive metabolite target analysis of more than 100 different compounds was performed. Both culturing and DGGE analysis showed that the species Lactobacillus sanfranciscensis, Lactobacillus paralimentarius, Lactobacillus plantarum, and Lactobacillus pontis dominated the LAB population of Belgian type I sourdoughs. In addition, DGGE band sequence analysis demonstrated the presence of Acetobacter sp. and a member of the Erwinia/Enterobacter/Pantoea group in some samples. Overall, the culture-dependent and culture-independent approaches each exhibited intrinsic limitations in assessing bacterial LAB diversity in Belgian sourdoughs. Irrespective of the LAB biodiversity, a large majority of the sugar and amino acid metabolites were detected in all sourdough samples. Principal component-based analysis of biodiversity and metabolic data revealed only little variation among the two samples of the sourdoughs produced at the same bakery. The rare cases of instability observed could generally be linked with variations in technological parameters or differences in detection capacity between culture-dependent and culture-independent approaches. Within a sampling interval of 1 year, this study reinforces previous observations that the bakery environment rather than the type or batch of flour largely determines the development of a stable LAB population in sourdoughs.
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