scholarly journals Variability of Bacterial Biofilms of the “Tina” Wood Vats Used in the Ragusano Cheese-Making Process

2007 ◽  
Vol 73 (21) ◽  
pp. 6980-6987 ◽  
Author(s):  
G. Licitra ◽  
J. C. Ogier ◽  
S. Parayre ◽  
C. Pediliggieri ◽  
T. M. Carnemolla ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Gc Content ◽  
Streptococcus Thermophilus ◽  
Raw Milk ◽  
Lactobacillus Delbrueckii ◽  
Universal Primers ◽  
Molecular Fingerprinting ◽  
Specific Pcr ◽  
Before And After ◽  
Gradient Gel Electrophoresis

ABSTRACT Ragusano cheese is a “protected denomination of origin” cheese made in the Hyblean region of Sicily from raw milk using traditional wooden tools, without starter. To explore the Ragusano bacterial ecosystem, molecular fingerprinting was conducted at different times during the ripening and biofilms from the wooden vats called “tinas” were investigated. Raw milks collected at two farm sites, one on the mountain and one at sea level, were processed to produce Ragusano cheese. Raw milk, curd before and after cooking, curd at stretching time (cheese 0 time), and cheese samples (4 and 7 months) were analyzed by PCR-temporal temperature gel electrophoresis (PCR-TTGE) and by classical enumeration microbiology. With the use of universal primers, PCR-TTGE revealed many differences between the raw milk profiles, but also notable common bands identified as Streptococcus thermophilus, Lactobacillus lactis, Lactobacillus delbrueckii, and Enterococcus faecium. After the stretching, TTGE profiles revealed three to five dominant species only through the entire process of ripening. In the biofilms of the two tinas used, one to five species were detected, S. thermophilus being predominant in both. Biofilms from five other tinas were also analyzed by PCR-TTGE, PCR-denaturating gradient gel electrophoresis, specific PCR tests, and sequencing, confirming the predominance of lactic acid bacteria (S. thermophilus, L. lactis, and L. delbrueckii subsp. lactis) and the presence of a few high-GC-content species, like coryneform bacteria. The spontaneous acidification of raw milks before and after contact with the five tinas was followed in two independent experiments. The lag period before acidification can be up to 5 h, depending on the raw milk and the specific tina, highlighting the complexity of this natural inoculation system.

scholarly journals Development and Validation of a Nested-PCR-Denaturing Gradient Gel Electrophoresis Method for Taxonomic Characterization of Bifidobacterial Communities

2003 ◽  
Vol 69 (11) ◽  
pp. 6380-6385 ◽  
Author(s):  
R. Temmerman ◽  
L. Masco ◽  
T. Vanhoutte ◽  
G. Huys ◽  
J. Swings
Keyword(s):  
Nested Pcr ◽  
Gel Electrophoresis ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Temporal Changes ◽  
Rrna Gene ◽  
Specific Pcr ◽  
Gradient Gel Electrophoresis ◽  
Species Specific ◽  
Taxonomic Characterization

ABSTRACT The taxonomic characterization of a bacterial community is difficult to combine with the monitoring of its temporal changes. None of the currently available identification techniques are able to visualize a “complete” community, whereas techniques designed for analyzing bacterial ecosystems generally display limited or labor-intensive identification potential. This paper describes the optimization and validation of a nested-PCR-denaturing gradient gel electrophoresis (DGGE) approach for the species-specific analysis of bifidobacterial communities from any ecosystem. The method comprises a Bifidobacterium-specific PCR step, followed by purification of the amplicons that serve as template DNA in a second PCR step that amplifies the V3 and V6-V8 regions of the 16S rRNA gene. A mix of both amplicons is analyzed on a DGGE gel, after which the band positions are compared with a previously constructed database of reference strains. The method was validated through the analysis of four artificial mixtures, mimicking the possible bifidobacterial microbiota of the human and chicken intestine, a rumen, and the environment, and of two fecal samples. Except for the species Bifidobacterium coryneforme and B. indicum, all currently known bifidobacteria originating from various ecosystems can be identified in a highly reproducible manner. Because no further cloning and sequencing of the DGGE bands is necessary, this nested-PCR-DGGE technique can be completed within a 24-h span, allowing the species-specific monitoring of temporal changes in the bifidobacterial community.

Identification of starter cultures in thermally treated plain yogurt using gene probes and polymerase chain reaction

1996 ◽  
Vol 63 (4) ◽  
pp. 607-613 ◽  
Author(s):  
Sonja Lick ◽  
Martina Keller ◽  
Uli Krusch ◽  
Knut J. Heller
Keyword(s):  
Polymerase Chain Reaction ◽  
Streptococcus Thermophilus ◽  
Starter Cultures ◽  
Lactobacillus Delbrueckii ◽  
Agarose Gel Electrophoresis ◽  
Chain Reaction ◽  
Specific Pcr ◽  
Specific Hybridization ◽  
Polymerase Chain ◽  
Species Specific

SummaryPlain yogurts (set type) fermented by three different starter cultures were subjected to different heat treatments (20 s at 72, 80 or 100 ·C, or 30 min at 60, 70, 80 or 100 ·C). DNA was extracted from each yogurt and analysed by agarose gel electrophoresis, by species-specific hybridization and by primer-specific polymerase chain reaction (PCR). Obvious degradation of DNA could be observed after heating at 80 ·C for 30 min and at 100 ·C for 20 s and 30 min. Identification ofLactobacillus delbrueckiiusing a species-specific hybridization fragment could be carried out in yogurt treated at 100 ·C for 20 s or for 30 min at lower temperatures. After treatment for 30 min at 100 ·C identification by hybridization was no longer possible. However, under the same conditions identification of starter microorganisms was still possible by primer-specific PCR, and this was demonstrated as an example forStreptococcus thermophilus.

scholarly journals Bifidobacterial Diversity in Human Feces Detected by Genus-Specific PCR and Denaturing Gradient Gel Electrophoresis

2001 ◽  
Vol 67 (2) ◽  
pp. 504-513 ◽  
Author(s):  
Reetta M. Satokari ◽  
Elaine E. Vaughan ◽  
Antoon D. L. Akkermans ◽  
Maria Saarela ◽  
Willem M. de Vos
Keyword(s):  
16S Rdna ◽  
Gel Electrophoresis ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Methodological Approach ◽  
Common Species ◽  
Bifidobacterium Adolescentis ◽  
Specific Pcr ◽  
Rdna Sequences ◽  
Pcr Products ◽  
Gradient Gel Electrophoresis

ABSTRACT We describe the development and validation of a method for the qualitative analysis of complex bifidobacterial communities based on PCR and denaturing gradient gel electrophoresis (DGGE).Bifidobacterium genus-specific primers were used to amplify an approximately 520-bp fragment from the 16S ribosomal DNA (rDNA), and the fragments were separated in a sequence-specific manner in DGGE. PCR products of the same length from different bifidobacterial species showed good separation upon DGGE. DGGE of fecal 16S rDNA amplicons from five adult individuals showed host-specific populations of bifidobacteria that were stable over a period of 4 weeks. Sequencing of fecal amplicons resulted in Bifidobacterium-like sequences, confirming that the profiles indeed represent the bifidobacterial population of feces. Bifidobacterium adolescentis was found to be the most common species in feces of the human adult subjects in this study. The methodological approach revealed intragenomic 16S rDNA heterogeneity in the type strain of B. adolescentis, E-981074. The strain was found to harbor five copies of 16S rDNA, two of which were sequenced. The two 16S rDNA sequences of B. adolescentis E-981074T exhibited microheterogeneity differing in eight positions over almost the total length of the gene.

scholarly journals Molecular Profiling of the Clostridium leptum Subgroup in Human Fecal Microflora by PCR-Denaturing Gradient Gel Electrophoresis and Clone Library Analysis

2006 ◽  
Vol 72 (8) ◽  
pp. 5232-5238 ◽  
Author(s):  
Jian Shen ◽  
Baorang Zhang ◽  
Guifang Wei ◽  
Xiaoyan Pang ◽  
Hua Wei ◽  
...  
Keyword(s):  
Clone Library ◽  
Gel Electrophoresis ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Rrna Gene ◽  
Specific Pcr ◽  
Clone Library Analysis ◽  
Pcr Products ◽  
Gradient Gel Electrophoresis ◽  
Universal Bacterial Primer ◽  
Group Specific Primer

ABSTRACT A group-specific PCR-based denaturing gradient gel electrophoresis (DGGE) method was developed and combined with group-specific clone library analysis to investigate the diversity of the Clostridium leptum subgroup in human feces. PCR products (length, 239 bp) were amplified using C. leptum cluster-specific primers and were well separated by DGGE. The DGGE patterns of fecal amplicons from 11 human individuals revealed host-specific profiles; the patterns for fecal samples collected from a child for 3 years demonstrated the structural succession of the population in the first 2 years and its stability in the third year. A clone library was constructed with 100 clones consisting of 1,143-bp inserts of 16S rRNA gene fragments that were amplified from one adult fecal DNA with one forward universal bacterial primer and one reverse group-specific primer. Eighty-six of the clones produced the 239-bp C. leptum cluster-specific amplicons, and the remaining 14 clones did not produce these amplicons but still phylogenetically belong to the subgroup. Sixty-four percent of the clones were related to Faecalibacterium prausnitzii (similarity, 97 to 99%), 6% were related to Subdoligranulum variabile (similarity, ∼99%), 2% were related to butyrate-producing bacterium A2-207 (similarity, 99%), and 28% were not identified at the species level. The identities of most bands in the DGGE profiles for the same adult were determined by comigration analysis with the 86 clones that harbored the 239-bp group-specific fragments. Our results suggest that DGGE combined with clone library analysis is an effective technique for monitoring and analyzing the composition of this important population in the human gut flora.

scholarly journals Molecular Fingerprinting of Dairy Microbial Ecosystems by Use of Temporal Temperature and Denaturing Gradient Gel Electrophoresis

2004 ◽  
Vol 70 (9) ◽  
pp. 5628-5643 ◽  
Author(s):  
J.-C. Ogier ◽  
V. Lafarge ◽  
V. Girard ◽  
A. Rault ◽  
V. Maladen ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Dairy Products ◽  
Pathogenic Bacteria ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Bacterial Species ◽  
Reference Database ◽  
Molecular Fingerprinting ◽  
Genetic Profiling ◽  
Spoilage Bacteria ◽  
Gradient Gel Electrophoresis

ABSTRACT Numerous microorganisms, including bacteria, yeasts, and molds, constitute the complex ecosystem present in milk and fermented dairy products. Our aim was to describe the bacterial ecosystem of various cheeses that differ by production technology and therefore by their bacterial content. For this purpose, we developed a rapid, semisystematic approach based on genetic profiling by temporal temperature gradient electrophoresis (TTGE) for bacteria with low-G+C-content genomes and denaturing gradient gel electrophoresis (DGGE) for those with medium- and high-G+C-content genomes. Bacteria in the unknown ecosystems were assigned an identity by comparison with a comprehensive bacterial reference database of ∼150 species that included useful dairy microorganisms (lactic acid bacteria), spoilage bacteria (e.g., Pseudomonas and Enterobacteriaceae), and pathogenic bacteria (e.g., Listeria monocytogenes and Staphylococcus aureus). Our analyses provide a high resolution of bacteria comprising the ecosystems of different commercial cheeses and identify species that could not be discerned by conventional methods; at least two species, belonging to the Halomonas and Pseudoalteromonas genera, are identified for the first time in a dairy ecosystem. Our analyses also reveal a surprising difference in ecosystems of the cheese surface versus those of the interior; the aerobic surface bacteria are generally G+C rich and represent diverse species, while the cheese interior comprises fewer species that are generally low in G+C content. TTGE and DGGE have proven here to be powerful methods to rapidly identify a broad range of bacterial species within dairy products.

scholarly journals Taxonomic and Strain-Specific Identification of the Probiotic Strain Lactobacillus rhamnosus 35 within the Lactobacillus casei Group

2008 ◽  
Vol 74 (9) ◽  
pp. 2679-2689 ◽  
Author(s):  
Sophie Coudeyras ◽  
Hélène Marchandin ◽  
Céline Fajon ◽  
Christiane Forestier
Keyword(s):  
Gel Electrophoresis ◽  
Lactobacillus Casei ◽  
Group Analysis ◽  
Lactobacillus Rhamnosus ◽  
Probiotic Strain ◽  
Subtractive Hybridization ◽  
Specific Pcr ◽  
Gradient Gel Electrophoresis ◽  
Species Type ◽  
Temperature Gradient Gel Electrophoresis

ABSTRACT Lactobacilli are lactic acid bacteria that are widespread in the environment, including the human diet and gastrointestinal tract. Some Lactobacillus strains are regarded as probiotics because they exhibit beneficial health effects on their host. In this study, the long-used probiotic strain Lactobacillus rhamnosus 35 was characterized at a molecular level and compared with seven reference strains from the Lactobacillus casei group. Analysis of rrn operon sequences confirmed that L. rhamnosus 35 indeed belongs to the L. rhamnosus species, and both temporal temperature gradient gel electrophoresis and ribotyping showed that it is closer to the probiotic strain L. rhamnosus ATCC 53103 (also known as L. rhamnosus GG) than to the species type strain. In addition, L. casei ATCC 334 gathered in a coherent cluster with L. paracasei type strains, unlike L. casei ATCC 393, which was closer to L. zeae; this is evidence of the lack of relatedness between the two L. casei strains. Further characterization of the eight strains by pulsed-field gel electrophoresis repetitive DNA element-based PCR identified distinct patterns for each strain, whereas two isolates of L. rhamnosus 35 sampled 40 years apart could not be distinguished. By subtractive hybridization using the L. rhamnosus GG genome as a driver, we were able to isolate five L. rhamnosus 35-specific sequences, including two phage-related ones. The primer pairs designed to amplify these five regions allowed us to develop rapid and highly specific PCR-based identification methods for the probiotic strain L. rhamnosus 35.

scholarly journals Molecular Fingerprinting by PCR-Denaturing Gradient Gel Electrophoresis Reveals Differences in the Levels of Microbial Diversity for Musty-Earthy Tainted Corks

2009 ◽  
Vol 75 (7) ◽  
pp. 1922-1931 ◽  
Author(s):  
Chantal Prat ◽  
Olaya Ruiz-Rueda ◽  
Rosalia Trias ◽  
Enriqueta Anticó ◽  
Dimitra Capone ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Small Contribution ◽  
Molecular Fingerprinting ◽  
Biological Degradation ◽  
Microbial Identification ◽  
Gradient Gel Electrophoresis ◽  
Bacteria And Fungi ◽  
Penicillium Variabile ◽  
Cork Stoppers

ABSTRACT The microbial community structure of cork with marked musty-earthy aromas was analyzed using denaturing gradient gel electrophoresis of amplified ribosomal DNA. Cork stoppers and discs were used for DNA extraction and were analyzed by using selective primers for bacteria and fungi. Stoppers clearly differed from discs harboring a different fungal community. Moreover, musty-earthy samples of both types were shown to have a specific microbiota. The fungi Penicillium glabrum and Neurospora spp. were present in all samples and were assumed to make only a small contribution to off-odor development. In contrast, Penicillium islandicum and Penicillium variabile were found almost exclusively in 2,4,6-trichloroanisole (TCA) tainted discs. Conversely, Rhodotorula minuta and Rhodotorula sloofiae were most common in cork stoppers, where only small amounts of TCA were detected. Alpha- and gammaproteobacteria were the most commonly found bacteria in either control or tainted cork stoppers. Specific Pseudomonas and Actinobacteria were detected in stoppers with low amounts of TCA and 2-methoxy-3,5-dimethylpyrazine. These results are discussed in terms of biological degradation of taint compounds by specific microorganisms. Reliable and straightforward microbial identification methods based on a molecular approach provided useful data to determine and evaluate the risk of taint formation in cork.

scholarly journals Monitoring the Bacterial Population Dynamics in Sourdough Fermentation Processes by Using PCR-Denaturing Gradient Gel Electrophoresis

2003 ◽  
Vol 69 (1) ◽  
pp. 475-482 ◽  
Author(s):  
Christiane B. Meroth ◽  
Jens Walter ◽  
Christian Hertel ◽  
Markus J. Brandt ◽  
Walter P. Hammes
Keyword(s):  
Gel Electrophoresis ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Baker’S Yeast ◽  
Pcr Analysis ◽  
Baker's Yeast ◽  
Predominant Species ◽  
Specific Pcr ◽  
Rye Flour ◽  
Gradient Gel Electrophoresis ◽  
Dna Pcr

ABSTRACT Four sourdoughs (A to D) were produced under practical conditions by using a starter mixture of three commercially available sourdough starters and a baker's yeast constitutively containing various species of lactic acid bacteria (LAB). The sourdoughs were continuously propagated until the composition of the LAB flora remained stable. Two LAB-specific PCR-denaturing gradient gel electrophoresis (DGGE) systems were established and used to monitor the development of the microflora. Depending on the prevailing ecological conditions in the different sourdough fermentations, only a few Lactobacillus species were found to be competitive and became dominant. In sourdough A (traditional process with rye flour), Lactobacillus sanfranciscensis and a new species, L. mindensis, were detected. In rye flour sourdoughs B and C, which differed in the process temperature, exclusively L. crispatus and L. pontis became the predominant species in sourdough B and L. crispatus, L. panis, and L. frumenti became the predominant species in sourdough C. On the other hand, in sourdough D (corresponding to sourdough C but produced with rye bran), L. johnsonii and L. reuteri were found. The results of PCR-DGGE were consistent with those obtained by culturing, except for sourdough B, in which L. fermentum was also detected. Isolates of the species L. sanfranciscensis and L. fermentum were shown by randomly amplified polymorphic DNA-PCR analysis to originate from the commercial starters and the baker's yeast, respectively.

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