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Microbial diversity of a Camembert-type cheese using freeze-dried Tibetan kefir coculture as starter culture by culture-dependent and culture-independent methods.

Mei J, Guo Q, Wu Y, Li Y - PLoS ONE (2014)

Bottom Line: SEM showed that the microbiota were dominated by a variety of lactobacilli (long and curved) cells growing in close association with a few yeasts in the inner portion of the grain and the short lactobacilli were observed along with yeast cells on the exterior portion.Results indicated that conventional culture method and PCR-DGGE should be combined to describe in maximal detail the microbiological composition in the cheese during ripening.The data could help in the selection of appropriate commercial starters for Camembert-type cheese.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Science and Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, P.R. China.

ABSTRACT
The biochemical changes occurring during cheese ripening are directly and indirectly dependent on the microbial associations of starter cultures. Freeze-dried Tibetan kefir coculture was used as a starter culture in the Camembert-type cheese production for the first time. Therefore, it's necessary to elucidate the stability, organization and identification of the dominant microbiota presented in the cheese. Bacteria and yeasts were subjected to culture-dependent on selective media and culture-independent polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) analysis and sequencing of dominant bands to assess the microbial structure and dynamics through ripening. In further studies, kefir grains were observed using scanning electron microscopy (SEM) methods. A total of 147 bacteria and 129 yeasts were obtained from the cheese during ripening. Lactobacillus paracasei represents the most commonly identified lactic acid bacteria isolates, with 59 of a total of 147 isolates, followed by Lactococcus lactis (29 isolates). Meanwhile, Kazachstania servazzii (51 isolates) represented the mainly identified yeast isolate, followed by Saccharomyces cerevisiae (40 isolates). However, some lactic acid bacteria detected by sequence analysis of DGGE bands were not recovered by plating. The yeast S. cerevisiae and K. servazzii are described for the first time with kefir starter culture. SEM showed that the microbiota were dominated by a variety of lactobacilli (long and curved) cells growing in close association with a few yeasts in the inner portion of the grain and the short lactobacilli were observed along with yeast cells on the exterior portion. Results indicated that conventional culture method and PCR-DGGE should be combined to describe in maximal detail the microbiological composition in the cheese during ripening. The data could help in the selection of appropriate commercial starters for Camembert-type cheese.

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Electron micrographs of Tibetan kefir grains.(a) Tibetan kefir grains; (b) grain surfaces at ×5 000; (c, e) Inner portion of kefir grain at ×15 000; (g) Inner portion of kefir grain at ×40 000; (d, f) Exterior portion of kefir grain at ×15 000; (h) Exterior portion of kefir grain at ×40 000.
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pone-0111648-g002: Electron micrographs of Tibetan kefir grains.(a) Tibetan kefir grains; (b) grain surfaces at ×5 000; (c, e) Inner portion of kefir grain at ×15 000; (g) Inner portion of kefir grain at ×40 000; (d, f) Exterior portion of kefir grain at ×15 000; (h) Exterior portion of kefir grain at ×40 000.

Mentions: The exterior surfaces of the Tibetan kefir grains looked smooth and shiny with the naked eye (Figure 2a). However, the grain surfaces, under SEM at a magnification of ×5000, were revealed to be very rugged (Figure 2b). In the inner portion of the grain (Figures 2c, 2e, ×15 000; 2g, ×40 000), a variety of lactobacilli (long and curved), yeasts and fibrillar material were observed. Kefir grains had a spongy fibrillar structure that was branched and interconnected. Fibrillar material increased progressively towards the interior portions of the grain. On the inner portions of the grain, there were a variety of lactobacilli (long and curved) with only a few yeasts embedded in the fibrillar material. Lactobacilli, yeasts and fibrillar material were also observed at × 15 000 (Figures 2d, 2f) and × 40 000 (Figures 2h) on the exterior portion of the grain. The fibrillar material was most probably the polysaccharide kefiran. The short lactobacilli were observed embedded in the grain along with yeast cells.


Microbial diversity of a Camembert-type cheese using freeze-dried Tibetan kefir coculture as starter culture by culture-dependent and culture-independent methods.

Mei J, Guo Q, Wu Y, Li Y - PLoS ONE (2014)

Electron micrographs of Tibetan kefir grains.(a) Tibetan kefir grains; (b) grain surfaces at ×5 000; (c, e) Inner portion of kefir grain at ×15 000; (g) Inner portion of kefir grain at ×40 000; (d, f) Exterior portion of kefir grain at ×15 000; (h) Exterior portion of kefir grain at ×40 000.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4216126&req=5

pone-0111648-g002: Electron micrographs of Tibetan kefir grains.(a) Tibetan kefir grains; (b) grain surfaces at ×5 000; (c, e) Inner portion of kefir grain at ×15 000; (g) Inner portion of kefir grain at ×40 000; (d, f) Exterior portion of kefir grain at ×15 000; (h) Exterior portion of kefir grain at ×40 000.
Mentions: The exterior surfaces of the Tibetan kefir grains looked smooth and shiny with the naked eye (Figure 2a). However, the grain surfaces, under SEM at a magnification of ×5000, were revealed to be very rugged (Figure 2b). In the inner portion of the grain (Figures 2c, 2e, ×15 000; 2g, ×40 000), a variety of lactobacilli (long and curved), yeasts and fibrillar material were observed. Kefir grains had a spongy fibrillar structure that was branched and interconnected. Fibrillar material increased progressively towards the interior portions of the grain. On the inner portions of the grain, there were a variety of lactobacilli (long and curved) with only a few yeasts embedded in the fibrillar material. Lactobacilli, yeasts and fibrillar material were also observed at × 15 000 (Figures 2d, 2f) and × 40 000 (Figures 2h) on the exterior portion of the grain. The fibrillar material was most probably the polysaccharide kefiran. The short lactobacilli were observed embedded in the grain along with yeast cells.

Bottom Line: SEM showed that the microbiota were dominated by a variety of lactobacilli (long and curved) cells growing in close association with a few yeasts in the inner portion of the grain and the short lactobacilli were observed along with yeast cells on the exterior portion.Results indicated that conventional culture method and PCR-DGGE should be combined to describe in maximal detail the microbiological composition in the cheese during ripening.The data could help in the selection of appropriate commercial starters for Camembert-type cheese.

View Article: PubMed Central - PubMed

Affiliation: Department of Food Science and Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, P.R. China.

ABSTRACT
The biochemical changes occurring during cheese ripening are directly and indirectly dependent on the microbial associations of starter cultures. Freeze-dried Tibetan kefir coculture was used as a starter culture in the Camembert-type cheese production for the first time. Therefore, it's necessary to elucidate the stability, organization and identification of the dominant microbiota presented in the cheese. Bacteria and yeasts were subjected to culture-dependent on selective media and culture-independent polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) analysis and sequencing of dominant bands to assess the microbial structure and dynamics through ripening. In further studies, kefir grains were observed using scanning electron microscopy (SEM) methods. A total of 147 bacteria and 129 yeasts were obtained from the cheese during ripening. Lactobacillus paracasei represents the most commonly identified lactic acid bacteria isolates, with 59 of a total of 147 isolates, followed by Lactococcus lactis (29 isolates). Meanwhile, Kazachstania servazzii (51 isolates) represented the mainly identified yeast isolate, followed by Saccharomyces cerevisiae (40 isolates). However, some lactic acid bacteria detected by sequence analysis of DGGE bands were not recovered by plating. The yeast S. cerevisiae and K. servazzii are described for the first time with kefir starter culture. SEM showed that the microbiota were dominated by a variety of lactobacilli (long and curved) cells growing in close association with a few yeasts in the inner portion of the grain and the short lactobacilli were observed along with yeast cells on the exterior portion. Results indicated that conventional culture method and PCR-DGGE should be combined to describe in maximal detail the microbiological composition in the cheese during ripening. The data could help in the selection of appropriate commercial starters for Camembert-type cheese.

Show MeSH