This study aimed to compare phenotypic and genetic characteristics of Lactobacillus rhamnosus strains isolated at the end of the ripening of Parmigiano Reggiano cheese and to investigate an important prerequisite of probiotic interest, such as the capability to survive at low pH and in presence of bile salts. The use of API 50 CH, RAPD-PCR analysis and species-specific PCR allowed to ascertain the identity of 63 L. rhamnosus strains. Three L. rhamnosus strains isolated from Parmigiano Reggiano cheese, L. rhamnosus ATCC 7469T and the commercial strain L. GG were assayed to estimate the resistance to various stress factors reproducing in vitro some conditions of the gastro-intestinal environment such as low pH and different amounts of bile salts and acids. The behaviour of almost all the tested strains isolated from Parmigiano Reggiano cheese resulted analogous to that showed by L. GG.

-This work aimed to evaluate the antibiotic susceptibility of 63 Lactobacillus rhamnosus strains isolated from Parmigiano Reggiano cheese, of Lactobacillus GG and of the type strain L. rhamnosus DSM 20021. Antimicrobial susceptibility was determined by the disc diffusion method on 41 antibiotics. Inhibition zone diameter was carefully measured and the results (the mean of four determinations) were expressed in terms of resistance or susceptibility. All the strains isolated from cheese showed resistance to six antibiotics (cefixime, vancomycin, neomycin, enoxacin, pefloxacin and sulphamethoxazole plus trimethoprim). The strain DSM 20021 T was resistant to nine antibiotics (the previous six plus cephalexin, bacitracin and lincomycin), while the commercial strain L. GG showed resistance to eighteen antibiotics. A high strain-specific resistance to different antibiotics was ascertained in Lactobacillus rhamnosus isolated from cheese. The results obtained in this study confirm that antibiotic resistance is a very important feature in the selection of potentially probiotic lactic acid bacteria.Lactobacillus rhamnosus / lactic acid bacteria / antibiotic susceptibility / cheese / probiotic Résumé -Sensibilité aux antibiotiques de souches de Lactobacillus rhamnosus isolées du fromage Parmigiano Reggiano. Le but de cette étude était l'évaluation de la sensibilité aux antibiotiques de 63 souches de Lactobacillus rhamnosus isolées du fromage Parmigiano Reggiano, de la souche Lactobacillus GG et de la souche type de L. rhamnosus DSM 20021. La sensibilité ou la résistance à 41 antibiotiques de ces 65 souches de L. rhamnosus a été déterminée avec le test de diffusion de disque en gélose. Les diamètres des zones d'inhibition, mesurés avec précision, ont permis d'individualiser pour chaque antibiotique testé les souches résistantes et celles sensibles. Toutes les souches isolées du fromage se sont avérées résistantes à six antibiotiques (céfixime, vancomycine, néomycine, enoxacine, péfloxacine et triméthoprime + sulfaméthoxazole). La souche type DSM 20021 T était résistante à neuf antibiotiques (les six précédents plus cefalexine, bacitracine et lincomycine), tandis que la souche commerciale L. GG a montré une résistance à 18 antibiotiques. Une résistance souche-spécifique à différents antibiotiques a été montrée pour les souches de Lactobacillus rhamnosus isolées du fromage. Les résultats obtenus dans cette étude ont confirmé que la résistance aux antibiotiques est une caractéristique très importante pour sélectionner les bactéries lactiques potentiellement probiotiques. Lactobacillus rhamnosus

myo-Inositol hexaphosphate (IP6) is the main source of phosphorus in cereal grains, and therefore, in bakery products. Different microorganisms such as yeasts and lactic acid bacteria have phytase enzymes able to hydrolyze IP6 during the wholemeal breadmaking. In this paper, the phytase activity of Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus curvatus, and Saccharomyces cerevisiae strains, isolated from southern Italian sourdoughs, is assayed using the (31)P NMR technique. The sourdough technology based on the use of lactic acid bacteria in the breadmaking is finally suggested.

No abstract