Showing papers by "Marta Hugas published in 1993"

Bacteriocinogenic activity of lactobacilli from fermented sausages

Abstract: During the screening of the inhibitory activity of 254 strains of lactobacilli isolated from fermented sausages at different times of ripening, 22% of the strains showed inhibition that was not related to acid or hydrogen peroxide, towards one or more indicator strains. Not all the strains were capable of secreting the inhibitory compound in the supernatant fluid. The characterization of the inhibitory compound from three strains showed that they were bacteriocins with a bactericidal mode of action and a molecular weight exceeding 10,000 Da. Lactobacillus plantarum CTC 305, CTC 306 and Lact. sake CTC 372 inhibited Listeria monocytogenes. Lactobacillus sake CTC 372 was cured of two plasmids of 84.8 kbp and 41.3 kbp, losing the production and the immunity of a bacteriocin as well as the ability to ferment lactose.

Electrotransformation of meat lactobacilli. Effect of several parameters on their efficiency of transformation

Abstract: Intact cells of several lactobacilli isolated from Spanish dry fermented sausages (Lactobacillus curvatus, Lact. sake, Lact. plantarum and Lact. bavaricus) were transformed by electroporation. With pNZ12 as a vector, transformation efficiencies of 2.4 times 105, 3.8 times 103 and 8.8 times 102 transformants μg-1 DNA were observed for Lact. curvatus CTC435, Lact. sake CTC335 and Lact. bavaricus CTC232, respectively. Effects of variation in experimental parameters on transformation efficiency were evaluated. Strains, vectors and buffers were the determinant parameters. The growth phase of the culture, cell concentration, voltage, use of cell wall weakening agents and the purity of the vector influenced the transformation efficiency in most strains.