Traditional dry smoked fermented meat sausages: Characterization of autochthonous enterococci

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Highlights

  • Characterization of enterococci isolated from 5 dry smoked fermented sausages produced in a Portuguese factory.

  • Evaluation of diversity, technological features and general safety.

  • Identification of features related with persistence in the manufacturing environment.

Abstract

Enterococci are known members of the native microbiota in traditional dry smoked fermented sausages, but their exact role continues to be poorly understood. In the present study, the genetic diversity, technological features and overall safety were assessed for one-hundred and forty-seven enterococci isolated from meat-sausages produced in Portugal (Catalão, Chouriço-Preto, Linguiça, Paio and Salsichão). Fingerprinting analysis revealed high similarity levels between isolates obtained from distinct products, which associated with a high metabolic versatility and the ability to produce biofilms, points towards the persistence of specific strains in the manufacturing environment.

Although the meat-enterococci harbor antibiotic resistances and produce biofilms, a reduced number of virulence factors were detected. Overall, a low risk is most likely associated with the presence of enterococci in these food products, especially if we consider the absence of reports regarding foodborne infections connected with the consumption of traditional sausages. However, the selection of enterococci as putative starters should remain cautious, since these microorganisms harbor concerning levels of antibiotic resistances, which may, or may not, be spread to other bacteria.

Introduction

In Mediterranean countries many meat fermented foods are manufactured carrying out artisanal ways, without the use of starter cultures. The autochthone microbiota is mostly dominated by lactic acid bacteria (LAB), with the presence of enterococci being mainly attributed to their phenotypic features, such as low acidification ability, proteolytic/lipolytic activities and carbohydrate metabolism, which may contribute to improve the characteristics of fermented products (Hugas, Garriga, & Aymerich, 2003). However, over the years there have been reports on Enterococcus spp. recovered from several sources which carry virulence and antibiorresistance traits, unlike most LAB (Barbosa et al., 2009, Belgacem et al., 2010, Ogier and Serror, 2008, Ribeiro et al., 2011, Semedo et al., 2003). In this context, the present study characterized enterococci collected from five dry smoked fermented meat-sausages, produced using artisanal procedures in a small-scale factory in Portugal. This research aimed to identify enterococcal features responsible for persistence in a manufacturing environment, as well as to assess for putative risk to the consumer.

Section snippets

Sampling and microbial isolation

Five distinct fermented-sausages were collected in a small-factory located at Alentejo, Portugal (Catalão, Chouriço-preto, Linguiça, Salsichão and Paio). These products have natural casings, present ±3 cm in diameter and are submitted to a smoking period of 48–72 h at 18-24 °C, followed by a curing/drying period of 25–40 days at 9 °C. Bacterial isolation was performed over a five-month period (three samples from each sausage, per month) as described (Ribeiro and others, 2011), using Slanetz and

Isolation, identification and genomic diversity of the meat-enterococci

All products analyzed harbored enterococci, between 104 CFU/g for Catalão, Chouriço-preto and Linguiça and below 102 CFU/g for Salsichão and Paio; bacterial counts were equivalent for SBA and SBA-VAN. In Portugal, fermented meat-sausages can present high counts of Enterococcus spp., with reports ranging from 104 to 108 CFU/g (Barbosa and others, 2009), to 103–104 CFU/g (Ribeiro and others, 2011), which are more similar to our findings.

From a total of 147 isolates, 73 were identified as

Conclusions

The enterococci recovered from five Portuguese traditional dry smoked fermented sausages belonged mainly to the species E. faecalis and E. faecium. The persistence of specific strains in the meat-products under analysis, over a five-month period, suggests the presence of a characteristic in house microbiota. Evaluation of the technological features of the isolates showed their ability to produce a wide spectrum of enzymes, which points to their importance in artisanal fermented sausage

Author contributions

SCS carried out experimental work and manuscript drafting; MJF, ME and ASB performed critical revision of the manuscript; TSL was involved in the conception, design and supervision of the experimental work and data analysis, performed manuscript revision and submission. All authors read and approved the final manuscript.

Acknowledgements

This study was performed at ‘‘Centro de Investigação Interdisciplinar em Sanidade Animal’’, Faculty of Veterinary Medicine, University of Lisbon (CIISA/FMV), with the financial support of Projects UID/CVT/00276/2013 and PTDC/AGR-ALI/119075/2010 (Fundação para a Ciência e Tecnologia -FCT-) and project PRODER nº 13017 (European Agricultural Fund for Rural Development). Teresa Semedo-Lemsaddek is financially supported by FCT (SFRH/BPD/108123/2015). Authors thank Snigdadip Dey and Bruno Afonso for

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