A.M. Cosseddu

Evolution and identification of lactic acid bacteria isolated during the ripening of Sardinian sausages

Lactic acid bacteria (LAB) were isolated during the production and the ripening of Sardinian sausage, a typical Italian dry fermented sausage. Samples were taken at different stages, and 112 strains were isolated. The isolates were characterized using the micromethod proposed by Font de Valdez et al. [Font de Valdez, G., Savoy de Giori, G., Oliver, G., & De Ruiz Holgado, A. P. (1993). Development and optimization of an expensive microsystem for the biochemical characterization of lactobacilli. Microbiologie Aliments Nutrition, 11, 215-219]. Schillinger and Lückes [Schillinger, U., & Lücke, F. K. (1987). Identification of lactobacilli from meat and meat products. Food Microbiology. (4), 199-208] scheme and the biochemical patterns given by Bergeys Manual of Systematic Bacteriology [Bergeys Manual of Systematic Bacteriology (1986). Baltimore: William and Wilkins] were used for preliminary identification. A PCR-based method was then used to confirm the results. LAB were the dominant flora during ripening. They consisted mainly of homofermentative mesophilic rods. Lactobacillus sakei (43,3%), Lactobacillus plantarum (16,6%) and Lactobacillus curvatus (13,3%) were the main isolates. The results of the biochemical identification methods agreed well with those of PCR-based identification (91% agreement).

Multiplex PCR for the Identification and Serotyping of L. monocytogenes Isolated from Sheep Cheese-Processing Plants

De Santis, E.P.L., Pilo, A.L., Cosseddu, A.M., Canu, N.A., Scarano and C., Marongiu, P., 2007. Multiplex PCR for the identification and serotyping of L. monocytogenes isolated from sheep cheese-processing plants. Veterinary Research Communications, 31(Suppl. 1), 359–363

The pattern of toxin genes and expression of diarrheal enterotoxins in Bacillus thuringiensis strains isolated from commercial bioinsecticides.

Bacillus thuringiensis (Bt) is a gram positive sporeforming bacillus included in the Bacillus cereus group. Bt produces a parasporal insecticidal protein crystal, a protoxin of the δ-endotoxin that has insecticidal properties (Schnepf et al . 1998). Bt has been used in bioinsecticidal formulations for decades and it is either sprayed directly on plants or else used to coat the seeds. However, some outbreaks of foodborne disease due to Bt have been reported and a large number of its strains can produce enterotoxins (EFSA 2007). Bacillus cereus (Bc) is the most representative species of the Bacillus cereus group and is identified as the species of this group that typically causes foodborne disease in humans. Bc does not produce the parasporal crystal. It can develop and produce toxins in food, causing emetic syndrome, or in the human intestine, causing gastroenteritis (Schoeni and Wong 2005).

Characterization of Sarda sheep carcasses used in the processing of meat products.

Meat quality is perceived by consumers as being connected with certain sensory characteristics. These are colour, texture, fragrance and tenderness (Ruiz De Huidobro et al ., 2003). Some authors have studied the relationship between the different productive parameters such as rearing system, age, sex, etc., and the biological characteristics of muscles, sensory parameters, or those of economic interest such as carcass conformation and slaughter yield (Mandell et al ., 1998; Byrne et al ., 2000; Maltin et al ., 2001; Maher et al ., 2004; Sami et al ., 2004). The research on sheep has concentrated on evaluating the quality of lamb meat (Arsenos et al ., 2002; Priolo et al ., 2002; Santos-Silva et al ., 2002). There is a dearth of information on adult ovine meat, which is little appreciated and economically undervalued. This study is designed to evaluate some quality aspects of Sarda sheep carcasses used in the processing of meat products, in order to meet producer demand for a system that is able to measure meat quality. The technology and characteristics of adult sheep meat products have been described in previous studies (Mazzette et al ., 2001).