Effect of bacteriocin-producing lactobacilli on the survival of Escherichia coli and Listeria in a dynamic model of the stomach and the small intestine

The survival of Lactobacillus curvatus LTH 1174 (bac+) and (bac-) in combination with Escherichia coli LTH 1600 or Listeria innocua DSM20649 during transit through a dynamic model of the human stomach and small intestine (GIT model) was studied. Furthermore, we determined the digestion of curvacin A during gastro-intestinal transit and the effect of this bacteriocin on microbial survival. Lb. curvatus is rapidly killed in the gastric compartment at pH strongly agitated > agitated. Lactic acid and curvacin A enhanced the lethal effect of low pH on E. coli. Accordingly, cells from strongly agitated cultures were killed faster in the gastric compartment of the GIT model than those from agitated cultures, and inactivation was accelerated in the presence of curvacin A. E. coli tolerated the bile concentrations prevailing in the small intestinal compartments of the model. The survival of Listeria innocua in the GIT model was comparable to that of Lb. curvatus. The curvacin A produced by Lb. curvatus LTH1174 (bac+) killed > 90% of the L. innocua within 10 min after mixing of the cultures. Curvacin A was not degraded in the the gastric compartment, and could be detected in the ileal compartment during the first 180 min upon addition of the meal

Biologische Sicherheit der mit Hilfe der Gentechnik erzeugten Lebensmittel -Produkte ohne lebende Organismen Schlussbericht

Available from TIB Hannover: F99B119+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Molecular characterisation of Lactobacillus curvatus and L. sake isolated from sauerkraut and their application in sausage fermentations

Lactobacillus curvatus and L. sake are the organisms most adapted to meat fermentations and dominate the flora during the whole process. In fermenting sauerkraut Leuconostoc mesenteroides subsp. mesenteroides is the major organism only during the early phase. In this environment L. curvatus and L. sake provide up to 50% of the microbial flora especially of the later phase, depending on the process conditions. Strains of L. curvatus and L. sake isolated from fermenting sauerkraut were identified by hybridization with species specific 23S rRNA-targeted oligonucleotide probes and further characterized. In 59 of 72 strains plasmid DNA was detected. Small cryptic plasmids of 20 strains were found to be homologous to pLc2, a 2.6 kb plasmid from L. curvatus LTH683, which was originally isolated from meat. The ability to compete was investigated in fermenting sausages of two strains each of L. curvatus and L. sake isolated from sauerkraut. One strain each of L. curvatus and L. sake was found to outnumber the meatborne flora and govern the processSIGLEAvailable from TIB Hannover: D.Dt.F. QN1(1,53) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman