Biomedical subjects

Cecilia Fontana

Publications and source records attributed to Cecilia Fontana.

3 recordsLinked to original sources

PubMed2005

Monitoring the bacterial population dynamics during fermentation of artisanal Argentinean sausages.

The dynamics of the microbial community responsible for the artisanal fermentation of dry sausage produced in Argentina was investigated by using classical and molecular approaches. The combined use of RAPD analysis with primers M13, XD9, RAPD1 and RAPD2 and 16S rDNA sequencing were applied to the identification and intraspecific differentiation of 100 strains of lactobacilli and Micrococcaceae. DGGE analysis was used to monitor the dynamic changes in population after total microbial DNA was directly extracted from sausages and subjected to PCR using V3f (GC), Bact-0124f-GC and Univ-0515r primers. The sequence analysis of 16S rDNA of the dominant species was also carried out. Lactobacillus sakei and Lactobacillus plantarum were the dominant lactic acid organisms during the fermentation while Staphylococcus saprophyticus represented the dominant species of Micrococcaceae. It was demonstrated that the ripening process of Argentinean artisanal fermented sausage is driven by a limited number of Lactobacillus and Staphylococcus strains selected from environmental microbiota by the ability to best compete under the prevailing conditions of the ecological niche. The identification of dominant communities present in this artisanal fermented sausage can help in the selection of starter cultures consisting in well adapted strains to the particular production technology.

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PubMed2005

PCR-DGGE analysis for the identification of microbial populations from Argentinean dry fermented sausages.

Different PCR-DGGE protocols were evaluated to monitor fermentation process and to investigate bacterial communities developed in two artisanal Argentinean fermented sausages. Bacterial universal primers frequently used in PCR-denaturing gradient gel electrophoresis (DGGE) were evaluated. Lactic acid bacteria (LAB) and staphylococci species isolated from Tucumán sausages were used to determine the experimental conditions for PCR amplification and DGGE differentiation. Total microbial DNA extracted directly from both fermented sausages was subjected to DGGE analysis. PCR-DGGE results were different for each set of primers used. Primers Bact-0124f(GC)-Uni-0515r and V1f(GC)-V1r showed to be efficient to differentiate LAB and Staphylococcus cultures while the set V3f(GC)-Uni-0515r allowed to demonstrate the succession of different Lactobacillus and Staphylococcus species during ripening process. An intense band corresponding to Lactobacillus sakei was observed to be present in both samples. Staphylococcus saprophyticus was only observed in Tucumán sausage while a band identified as Brochothrix thermophacta was detected in Córdoba sausage. PCR-DGGE analysis of different 16S rDNA amplicons was able to discriminate between LAB and Gram-positive, coagulase-negative cocci, resulting an effective tool to establish the microbiota developed in artisanal dry sausages.

Animals↗

PubMed2004

Meat-model system development for proteolytic activity determination.

Many technological parameters that affect the nature and functional properties of proteins are involved in the preparation of meat products. The dry-curing process is quite complex because of the coexistence of enzymes from endogenous and bacterial origins. The protein breakdown that takes place during the ripening of dry fermented sausages leads to an increase in the concentration of peptides and free amino acids. The proteolytic events have been thoroughly investigated not only because of their physiological significance but also for their technological connotations in terms of texture and flavor development. Lactic acid bacteria and Staphylococcus or Kocuria are used as starter cultures in fermented meat products. In recent years, the proteolytic system of lactobacilli involved in meat fermentation became the focus of an increasing number of studies because of the technological roles of these organisms. Although results obtained from broth systems show proteolytic activity, studies involving food systems must be done to confirm their effectiveness. A simplified soluble muscle extract to determine the capacity to degrade meat proteins by lactic acid bacteria was developed using a spectrophotometric method based on the reaction of the alpha-amino groups released by hydrolysis with o-phtaldialdehyde and beta-mercaptoethanol to form an adduct (1-thioalkyl-2-alkylisoindoles) that is enhanced at basic pH and absorbs strongly at 360 nm.

Animals↗