The microbial ecology of a typical Italian salami during its natural fermentation

• Published in: International journal of food microbiology Vol. 120; no. 1; pp. 136 - 145
• Main Authors: Aquilanti, Lucia, Santarelli, Sara, Silvestri, Gloria, Osimani, Andrea, Petruzzelli, Annalisa, Clementi, Francesca
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 30-11-2007; Elsevier
• Subjects: bacterial contamination; Biological and medical sciences; Ciauscolo; Coagulase negative cocci; coagulase negative staphylococci; Colony Count, Microbial; culture media; Debaryomyces hansenii; DNA, Bacterial - analysis; DNA, Fungal - analysis; Electrophoresis, Polyacrylamide Gel - methods; Fermentation; fermented foods; Fermented sausages; Food industries; Food Microbiology; food spoilage; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Italy; Lactic acid bacteria; Lactobacillus; Lactobacillus - genetics; Lactobacillus - isolation & purification; meat aging; Meat and meat product industries; Meat Products - microbiology; microbial detection; microbial load; Molecular Sequence Data; molecular systematics; PCR–DGGE; Polymerase Chain Reaction; Rhodotorula; RNA, Ribosomal, 16S - chemistry; RNA, Ribosomal, 16S - genetics; salami; Sequence Analysis, DNA; Staphylococcus - genetics; Staphylococcus - isolation & purification; Staphylococcus xylosus; traditional foods; Trichosporon; Water - metabolism; water activity; water content; Yeasts; Yeasts - genetics; Yeasts - isolation & purification; Italy; Yeasts; Lactic acid bacteria; Coagulase negative cocci; Ciauscolo; Fermented sausages; PCR–DGGE; Sausage; Yeast; Meat product; Pork product; PCR-DGGE; Fermentation; Fermented product; Polymerase chain reaction; Salami; Molecular biology
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2007.06.010

We have investigated the bacteria and yeast ecology of the typical Italian
Ciauscolo salami that is produced in Central Italy using a polyphasic approach based on culture-dependent and -independent methods. The physico-chemical analyses showed a progressive drop in pH and water activity (
a
w) during ripening. The viable counts revealed a dominance of lactic acid bacteria (LAB) over coagulase negative cocci (CNC) and yeasts. From the molecular identification of the isolates, the prevalence of
Lactobacillus curvatus, Lb. plantarum and
Staphylococcus xylosus was shown among the bacteria, while
Debaryomyces hansenii was the prevalent species among the yeasts, and it was isolated throughout the whole ripening process. Minority species, namely
Rhodotorula mucillaginosa and
Trichosporon brassicae, were also recovered from the meat batter.
The total microbial community was profiled without cultivation by analyzing the DNA that was directly extracted from the salami samples. Moreover, the cultivable community was profiled by analyzing the DNA recovered from bulk cells that were obtained by harvesting the colonies from serial-dilution agar plates. The 16S rRNA gene V1 and V3 regions were used as targets in the denaturing gradient gel electrophoresis (DGGE) profiling of the LAB and CNC communities, respectively, while the diversity and dynamics of the yeast population were assessed by analyzing a portion of the 28S rRNA gene.
Our findings suggest that the microbial diversity of fermented meat products can be successfully investigated by this polyphasic approach that is based on the assessment of both the total and the cultivable community diversity.