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Food Microbiol. 2015 Aug;49:123-33. doi: 10.1016/j.fm.2015.01.017. Epub 2015 Feb 7.

Bacteria and yeast microbiota in milk kefir grains from different Italian regions.

Author information

1
Dipartimento di Scienze Agrarie, Alimentari ed Ambientali, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
2
Dipartimento di Scienze Agrarie, Alimentari ed Ambientali, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy. Electronic address: a.osimani@univpm.it.
3
Dipartimento di Agraria, Università degli Studi di Napoli Federico II, Via Università 100, 80055 Portici, Napoli, Italy.
4
Dipartimento di Scienze Agrarie, Alimentari e Ambientali & Industrial Yeasts Collection DBVPG, Università degli Studi di Perugia, Borgo XX Giugno, 06121 Perugia, Italy.

Abstract

Kefir grains are a unique symbiotic association of different microrganisms, mainly lactic acid bacteria, yeasts and occasionally acetic acid bacteria, cohabiting in a natural polysaccharide and a protein matrix. The microbial composition of kefir grains can be considered as extremely variable since it is strongly influenced by the geographical origin of the grains and by the sub-culturing method used. The aim of this study was to elucidate the bacteria and yeast species occurring in milk kefir grains collected in some Italian regions by combining the results of scanning electron microscopy analysis, viable counts on selective culture media, PCR-DGGE and pyrosequencing. The main bacterial species found was Lactobacillus kefiranofaciens while Dekkera anomala was the predominant yeast. The presence of sub-dominant species ascribed to Streptococcus thermophilus, Lactococcus lactis and Acetobacter genera was also highlighted. In addition, Lc. lactis, Enterococcus sp., Bacillus sp., Acetobacter fabarum, Acetobacter lovaniensis and Acetobacter orientalis were identified as part of the cultivable community. This work further confirms both the importance of combining culture-independent and culture-dependent approaches to study microbial diversity in food and how the combination of multiple 16S rRNA gene targets strengthens taxonomic identification using sequence-based identification approaches.

KEYWORDS:

Acetic acid bacteria; Lactic acid bacteria; Microbial diversity; PCR-DGGE; Pyrosequencing; SEM analysis; Yeasts

PMID:
25846922
DOI:
10.1016/j.fm.2015.01.017
[Indexed for MEDLINE]

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