Lactic acid bacteria ecology of three traditional fermented sausages produced in the North of Italy as determined by molecular methods.

In this study the bacterial biodiversity during the maturation process of three traditional sausages produced in the North of Italy (Salame bergamasco, Salame cremonese and Salame mantovano) was investigated by using culture-dependent and -independent methods. Eleven plants, in the three provinces considered here, were selected because starter cultures were never used in the production. The bacterial ecology, as determined by plate counts, was dominated by lactic acid bacteria (LAB), with minor contribution of coagulase negative cocci and yeasts.

Microflora of Feta cheese from four Greek manufacturers.

The components of the microflora of four Feta cheeses, produced by different Greek manufacturers, were determined by culture dependent and independent techniques. Isolates from microbiological media were first grouped by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) and then representatives of each DGGE group were sequenced for identification purposes. DNA and RNA, extracted directly from the cheese, were subjected to PCR-DGGE.

Spoilage of blood sausages morcilla de Burgos treated with high hydrostatic pressure.

In this study, the microbial ecology of the blood sausage morcilla de Burgos, subjected to high hydrostatic pressure treatment (HPP), was studied by culture-dependent and -independent methods. Morcilla de Burgos is the most traditional and famous blood sausage in Spain. The producers are interested in extending its shelf-life in order to expand their market and to reduce losses attributed to spoilage.

Yeast biodiversity and dynamics during sweet wine production as determined by molecular methods.

In this study we investigated yeast biodiversity and dynamics during the production of a sweet wine obtained from dried grapes. Two wineries were selected in the Collio region and grapes, grape juices and wines during fermentations were analyzed by culture-dependent methods (plating on WLN medium) and culture-independent methods (PCR-DGGE). Moreover, the capability of the Saccharomyces cerevisiae starter cultures to take over the fermentation was assessed by RAPD-PCR.

Detection, quantification and vitality of Listeria monocytogenes in food as determined by quantitative PCR.

In this paper we describe the development of a quantitative PCR (qPCR) technique to detect, quantify and determine the vitality of Listeria monocytogenes in foods. The method was based on the amplification of the intergenic region spacer (IGS) between the 16S and 23S rRNA genes. A panel of more than 100 strains of Listeria spp.

Optimization of conditions for profiling bacterial populations in food by culture-independent methods.

In this study we used culture-independent methods to profile bacterial populations in food products. Denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization (FISH) were employed in order to identify bacterial species without the need of isolation and biochemical identification. The protocols used to extract the DNA, subsequently subjected to PCR amplification for DGGE, as well as the hybridization procedure for FISH, were optimised.

Dynamics and characterization of yeasts during natural fermentation of Italian sausages.

A multiphasic approach was used to investigate the yeast ecology in Italian fermented sausages. Culture-dependent and -independent methods were applied to identify the yeast species during the maturation process and to characterize the numerically dominant species. Plating analysis and subsequent molecular identification of the isolates highlighted the dominance of Debaryomyces hansenii, but at least other three yeast species -Candida zeylanoides, Pichia triangularis and Metschnikowia pulcherrima - contributed to the fermentation as well.

Technological characterization of a bacteriocin-producing Lactobacillus sakei and its use in fermented sausages production.

The aim of this paper was the technological characterization of a Lactobacillus sakei strain, able to produce the bacteriocin sakacin P, that was originally isolated from naturally fermented sausages. Experiments were conducted in situ, using MRS-based medium, and in situ, when the strain was inoculated as starter culture in real sausage fermentation. The results obtained underlined that the strain was able to grow in conditions that are commonly used in the production line, and only lactose and high concentrations of NaCl (5% w/v) reduced the capability for bacteriocin production.

Ecology of lactic acid bacteria in Italian fermented sausages: isolation, identification and molecular characterization.

In this study, the ecology of the lactic acid bacteria (LAB) of three naturally fermented sausages produced in the Friuli-Venezia-Giulia region, in the North East of Italy, was investigated. A total of 465 strains isolated from three fermentations were identified by molecular methods and 12 different species of LAB were detected. Lactobacillus curvatus and Lactobacillus sakei were the most numerous (67 and 353 strains isolated, respectively) and they were subjected to RAPD-PCR.

Multiphasic approach to study the bacterial ecology of fermented sausages inoculated with a commercial starter culture.

In this paper, the ability of a commercial starter culture to perform a sausage fermentation is evaluated. Molecular analysis revealed the presence of several strains of the same species contained in the starter culture with different behavior during the fermentation, and the contribution of Lactobacillus curvatus, which was only marginally isolated during the transformation.

Sequencing and expression analysis of the sakacin P bacteriocin produced by a Lactobacillus sakei strain isolated from naturally fermented sausages.

A Lactobacillus sakei strain, designated as I151 and isolated from naturally fermented sausages, was found to produce the sakacin P bacteriocin which is active against Listeria monocytogenes. In this study, we performed the sequencing of the gene cluster involved in the production of the sakacin P, and we followed the expression of the sppA gene, encoding for the bacteriocin, in vitro, using Rogosa-Sharpe medium, and in situ, inoculating the strain in fermented sausages as starter culture. The results obtained underlined the high similarity (>99%) of the entire sakacin P gene cluster from the L.

Culture-dependent and -independent methods to investigate the microbial ecology of Italian fermented sausages.

In this study, the microbial ecology of three naturally fermented sausages produced in northeast Italy was studied by culture-dependent and -independent methods. By plating analysis, the predominance of lactic acid bacteria populations was pointed out, as well as the importance of coagulase-negative cocci. Also in the case of one fermentation, the fecal enterocci reached significant counts, highlighting their contribution to the particular transformation process.

Characterisation of naturally fermented sausages produced in the North East of Italy.

In the Friuli Venezia Giulia region, in the North East of Italy, a traditional fermented sausage is produced without the use of microbial starters. It is characterized at the end of the ripening period by accentuated acidity, slight sourness and elastic, semi-hard consistency. In this study, three fermentations, carried out in different seasons (winter, spring and summer) were followed analyzing the microbiological, physicochemical and sensory aspects of this product.

Moulds isolated from Istrian dried ham at the pre-ripening and ripening level.

The aim of this study is to define the mould strains growing on the surface during the pre-ripening and the ripening phases of Istrian ham, and their toxic potential. The mould microflora was predominantly represented by five genera, which were isolated on the ham surfaces of three different producers investigated. The identified species were similar in the both tested periods, demonstrating that the contamination came mainly from the air and the ripening chambers (seasoning rooms), rather than the raw meat.

Study of the ecology of fresh sausages and characterization of populations of lactic acid bacteria by molecular methods.

In this study, a polyphasic approach was used to study the ecology of fresh sausages and to characterize populations of lactic acid bacteria (LAB). The microbial profile of fresh sausages was monitored from the production day to the 10th day of storage at 4 degrees C. Samples were collected on days 0, 3, 6, and 10, and culture-dependent and -independent methods of detection and identification were applied.