Laboratoire Of Microbiologie Alimentaire Et Industrielle

Nantes, France

Laboratoire Of Microbiologie Alimentaire Et Industrielle

Nantes, France
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Lhomme E.,Laboratoire Of Microbiologie Alimentaire Et Industrielle | Orain S.,Laboratoire Of Microbiologie Alimentaire Et Industrielle | Courcoux P.,Laboratoire Of Statistiques Appliquees | Onno B.,Laboratoire Of Microbiologie Alimentaire Et Industrielle | And 2 more authors.
International Journal of Food Microbiology | Year: 2015

Fourteen bakeries located in different regions of France were selected. These bakers use natural sourdough and organic ingredients. Consequently, different organic sourdoughs used for the manufacture of French bread were studied by the enumeration of lactic acid bacteria (LAB) and 16S rRNA sequencing of the isolates. In addition, after DNA extraction the bacterial diversity was assessed by pyrosequencing of the 16S rDNA V1-V3 region. Although LAB counts showed significant variations (7.6-9.5log10CFU/g) depending on the sourdough studied, their identification through a polyphasic approach revealed a large predominance of Lactobacillus sanfranciscensis in all samples. In ten sourdoughs, both culture and independent methods identified L. sanfranciscensis as the dominant LAB species identified. In the remaining sourdoughs, culture methods identified 30-80% of the LAB as L. sanfranciscensis whereas more than 95% of the reads obtained by pyrosequencing belonged to L. sanfranciscensis. Other sub-dominant species, such as Lactobacillus curvatus, Lactobacillus hammesii, Lactobacillus paralimentarius, Lactobacillus plantarum, Lactobacillus pentosus, and Lactobacillus sakei, were also identified. Quantification of L. sanfranciscensis by real-time PCR confirmed the predominance of this species ranging from 8.24 to 10.38 log10CFU/g. Regarding the acidification characteristics, sourdough and related bread physico-chemical characteristics varied, questioning the involvement of sub-dominant species or L. sanfranciscensis intra-species diversity and/or the role of the baker's practices. © 2015 Elsevier B.V.


Michel E.,Laboratoire Of Microbiologie Alimentaire Et Industrielle | Michel E.,French National Institute for Agricultural Research | Monfort C.,Laboratoire Of Microbiologie Alimentaire Et Industrielle | Deffrasnes M.,Laboratoire Of Microbiologie Alimentaire Et Industrielle | And 6 more authors.
International Journal of Food Microbiology | Year: 2016

In order to contribute to the description of sourdough LAB composition, MiSeq sequencing and qPCR methods were performed in association with cultural methods. A panel of 16 French organic bakers and farmer-bakers were selected for this work. The lactic acid bacteria (LAB) diversity of their organic sourdoughs was investigated quantitatively and qualitatively combining (i) Lactobacillus sanfranciscensis-specific qPCR, (ii) global sequencing with MiSeq Illumina technology and (iii) molecular isolates identification. In addition, LAB and yeast enumeration, pH, Total Titratable Acidity, organic acids and bread specific volume were analyzed. Microbial and physico-chemical data were statistically treated by Principal Component Analysis (PCA) and Hierarchical Ascendant Classification (HAC). Total yeast counts were 6 log10 to 7.6 log10 CFU/g while LAB counts varied from 7.2 log10 to 9.6 log10 CFU/g. Values obtained by L. sanfranciscensis-specific qPCR were estimated between 7.2 and 10.3 log10 CFU/g, except for one sample at 4.4 log10 CFU/g. HAC and PCA clustered the sixteen sourdoughs into three classes described by their variables but without links to bakers' practices. L. sanfranciscensis was the dominant species in 13 of the 16 sourdoughs analyzed by Next Generation Sequencing (NGS), by the culture dependent method this species was dominant only in only 10 samples. Based on isolates identification, LAB diversity was higher for 7 sourdoughs with the recovery of L. curvatus, L. brevis, L. heilongjiangensis, L. xiangfangensis, L. koreensis, L. pontis, Weissella sp. and Pediococcus pentosaceus, as the most representative species. L. koreensis, L. heilongjiangensis and L. xiangfangensis were identified in traditional Asian food and here for the first time as dominant in organic sourdough. This study highlighted that L. sanfranciscensis was not the major species in 6/16 sourdough samples and that a relatively high LAB diversity can be observed in French organic sourdough. © 2016.


Lhomme E.,Laboratoire Of Microbiologie Alimentaire Et Industrielle | Onno B.,Laboratoire Of Microbiologie Alimentaire Et Industrielle | Chuat V.,French National Institute for Agricultural Research | Durand K.,French National Institute for Agricultural Research | And 4 more authors.
International Journal of Food Microbiology | Year: 2016

Lactobacillus sanfranciscensis is the predominant key lactic acid bacterium in traditionally fermented sourdoughs. Despite its prevalence, sourdough and their related breads could be different regarding their physicochemical and sensorial characteristics. The intraspecific diversity of L. sanfranciscensis might explain these observations. Fifty-nine strains isolated from French sourdoughs were typed by a polyphasic approach including Multilocus Sequence Typing (MLST) and Pulsed-field Gel Electrophoresis (PFGE), in order to study their genotypic diversity. MLST scheme can be reduced from six to four gene fragments (gdh, gyrA, nox and pta) without a major loss of discrimination between strains. The genes mapA and pgmA are not good candidates for inclusion in an MLST scheme to type L. sanfranciscensis strains, as they could not be amplified for a set of 18 strains among the 59 studied. This method revealed 20 sequence types (STs). Of these, 19 STs were grouped in one clonal complex, showing a strong relatedness between these strains. PFGE using SmaI discriminated 41 pulsotypes and so distinguished isolates better than the MLST scheme. Both genotypic methods indicate a low diversity between strains isolated from the same sourdough and a higher diversity between strains isolated from different sourdoughs, suggesting an influence of baker practices and/or environmental conditions on the selection of strains. The use of these two methods targeting genetic variations gives an optimal genotypic characterization of L. sanfranciscensis strains. © 2016 Elsevier B.V.


PubMed | Laboratoire Of Statistiques Appliquees, Laboratoire Of Microbiologie Alimentaire Et Industrielle and French National Institute for Agricultural Research
Type: | Journal: International journal of food microbiology | Year: 2015

Fourteen bakeries located in different regions of France were selected. These bakers use natural sourdough and organic ingredients. Consequently, different organic sourdoughs used for the manufacture of French bread were studied by the enumeration of lactic acid bacteria (LAB) and 16S rRNA sequencing of the isolates. In addition, after DNA extraction the bacterial diversity was assessed by pyrosequencing of the 16S rDNA V1-V3 region. Although LAB counts showed significant variations (7.6-9.5log10CFU/g) depending on the sourdough studied, their identification through a polyphasic approach revealed a large predominance of Lactobacillus sanfranciscensis in all samples. In ten sourdoughs, both culture and independent methods identified L. sanfranciscensis as the dominant LAB species identified. In the remaining sourdoughs, culture methods identified 30-80% of the LAB as L. sanfranciscensis whereas more than 95% of the reads obtained by pyrosequencing belonged to L. sanfranciscensis. Other sub-dominant species, such as Lactobacillus curvatus, Lactobacillus hammesii, Lactobacillus paralimentarius, Lactobacillus plantarum, Lactobacillus pentosus, and Lactobacillus sakei, were also identified. Quantification of L. sanfranciscensis by real-time PCR confirmed the predominance of this species ranging from 8.24 to 10.38log10CFU/g. Regarding the acidification characteristics, sourdough and related bread physico-chemical characteristics varied, questioning the involvement of sub-dominant species or L. sanfranciscensis intra-species diversity and/or the role of the bakers practices.

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