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Any bacterial strain to be used as starter culture should have suitable characteristics, including a lack of amino acid decarboxylase activity. In this study, the decarboxylase activity of 76 bacterial strains, including lactic acid bacteria and grampositive, catalase-positive cocci, was investigated. These strains were previously isolated from European traditional fermented sausages to develop autochthonous starter cultures. Of all the strains tested, 48% of the lactic acid bacteria strains and 13% of gram-positive, catalase-positive cocci decarboxylated one or more amino acids. Aminogenic potential was strain dependent, although some species had a higher proportion of aminogenic strains than did others. Thus, all Lactobacillus curvatus strains and 70% of Lactobacillus brevis strains had the capacity to produce tyramine and β-phenylethylamine. Some strains also produced other aromatic amines, such as tryptamine and the diamines putrescine and cadaverine. All the enterococcal strains tested were decarboxylase positive, producing high amounts of tyramine and considerable amounts of β-phenylethylamine. None of the staphylococcal strains had tyrosine-decarboxylase activity, but some produced other amines. From the aminogenic point of view, Lactobacillus plantarum, Lactobacillus sakei, and Staphylococcus xylosus strains would be the most suitable for use as autochthonous starter cultures for traditional fermented sausages. [ABSTRACT FROM AUTHOR]

Abstract: Microbial ecosystems were surveyed in 314 environmental samples from 54 Southern and Eastern European small-scale processing units (PUs) manufacturing traditional dry fermented sausages. The residual microflora contaminating the surfaces and the equipment were analysed after cleaning and disinfection procedures. All the PU environments were colonised at various levels by spoilage and technological microflora with excessive contamination levels in some of the PUs. Sporadic contamination by pathogenic microflora was recorded. Salmonella and Listeria monocytogenes were detected in 4.8% and 6.7% of the samples, respectively, and Staphylococcus aureus was enumerated in 6.1% of the samples. Several critical points were identified, such as the machines for S. aureus and the tables and the knives for L. monocytogenes; this knowledge is crucial for the improvement of hygiene control systems in small and traditional meat processing industries. The variability of the residual contamination emphasized the different cleaning, disinfecting and manufacturing practices routinely followed by these small-scale processing units. [Copyright &y& Elsevier]

Abstract: This paper reviews the diversity of microbiota, both in the environment and in traditional fermented European sausages. The environments of processing units were colonised at variable levels by resident spoilage and technological microbiota, with sporadic contamination by pathogenic microbiota. Several critical points were identified such as the machines, the tables and the knives – knowledge crucial for the improvement of cleaning and disinfecting practices. Traditionally fermented sausages generally did not present a sanitary risk. The great diversity of lactic acid bacteria and staphylococci was linked to manufacturing practices. Development of indigenous starters is very promising because it enables sausages to be produced with both high sanitary and sensory qualities. Our increasing knowledge of the genomes of technological bacteria will allow a better understanding of their physiology in sausages. [Copyright &y& Elsevier]

s.c. morot-bizot, r. talon and s. leroy. 2004.To develop a multiplex PCR that allows the identification of bacteria belonging to theStaphylococcusgenus and in particular to the speciesStaphylococcus xylosus,S. saprophyticus,S. epidermidisandS. aureusisolated from food manufacturing plants.Five primer pairs were used in the multiplex PCR, one specific to theStaphylococcusgenus and four specific toS. xylosus,S. saprophyticus,S. epidermidisandS. aureusspecies. All the 31Staphylococcusreference strains yielded a specific PCR product with the genus-specific primers.Staphylococcus xylosus,S. saprophyticus,S. epidermidisandS. aureusgave a specific PCR fragment with the corresponding species-specific primers. No amplification with theKocuria,MacrococcusandMicrococcusstrains was observed in our conditions. This multiplex PCR was performed on 30 strains of Gram-positive cocci isolated from different workshops and fermented sausages. Among them, 28 belonged to theStaphylococcusgenus and 14 were identified toS. saprophyticus, four toS. xylosus, two toS. aureusand one toS. epidermidis.This multiplex PCR provided reliable and repeatable PCR results. It allowed the identification of a major part of the isolates, highlighting the predominance of theS. saprophyticusspecies in the workshops studied.This tool is a useful way to screen the strains isolated from foodstuff and food environment and to monitor these species during the food processing. [ABSTRACT FROM AUTHOR]

Staphylococcus carnosus strain 833, inoculated into sausage, increased the levels of methyl ketones which contributed to the cured aroma. These ketones were predicted to arise from incomplete β-oxidation followed by a decarboxylation. To check this hypothesis, we measured the β-decarboxylase activity in resting cells of S. carnosus grown in complex or in synthetic medium, using as substrate a β-ketoacid, which can be an intermediate of the β-oxidation pathway. This activity was present throughout the growth period. The enzyme appeared to be constitutive because no induction was observed. High aeration, a pH of 5 and the presence of nitrate promoted the production of methyl ketones. [Copyright &y& Elsevier]