Valine transport and biodiversity of Leuconostoc wild strains from French raw milk cheeses.

The rate of L-valine transport in whole cells of Leuconostoc was at the maximum at 30 degrees C, pH 6.0 in the presence of an energy source. Transport was inhibited by 40-55%, in the presence of the ionophores (valinomycin, nigericin or monensin), and uncouplers (carbonyl cyanide-m-chloro-phenylhydrazone or 2,4-dinitrophenol) confirming the previously described delta p-driven branched-chain amino acid transport system described in cytoplasmic membranes (Winters et al., 1991, Appl. Environ. Microbiol., 57, 3350-3354). Sulfhydryl group reagents (p-chloro-mercuribenzoate, iodoacetate and N-ethyl maleimide) all inhibited valine transport by 60-70%, indicating that valine is actively transported at high valine concentration. Three kinetically distinguishable transport systems were identified for each strain using whole cells, confirming results obtained with membranes. L-valine transport Kt and Vmax could be an additional tool to estimate the biodiversity of 18 Leuconostoc strains belonging to the dominant flora of French raw milk cheeses. Kt values varied from 20 to 510 nmol/l for the very high affinity system, from 26 to 427 pmol/l for the high affinity system and from 0.65 to 4.40 mmol/l for the low affinity system. No correlation existed between valine transport rates and a particular strain's ability to acidify milk or complex media, suggesting that valine transport is not a growth-limiting function in species of the genus Leuconostoc.

Expression of Lactobacillus casei ATCC 393 beta-galactosidase encoded by plasmid pLZ15 in Lactococcus lactis CNRZ 1123.

Lactococcus lactis subsp. lactis CNRZ 1123, a Lac- derivative of CNRZ 1122 was transformed by electroporation with the Lactobacillus casei ATCC 393 plasmid pLZ15, which bears a beta-galactosidase gene. The transformants expressed a constitutive beta-galactosidase activity at a higher level than in Lact. casei, and in the cell-free extract two additional protein bands were detected by SDS-PAGE which could correspond to lactose metabolism enzymes. Both plasmid and beta-gal activity were stable in Lactococcus after 100 generations in glucose-containing medium.

Branched-Chain Amino Acid Transport in Cytoplasmic Membranes of Leuconostoc mesenteroides subsp. dextranicum CNRZ 1273.

Membrane vesicles of Leuconostoc mesenteroides subsp. dextranicum fused with proteoliposomes prepared from Escherichia coli phospholipids containing beef heart cytochrome c oxidase were used to study the transport of branched-chain amino acids in a strain isolated from a raw milk cheese. At a medium pH of 6.0, oxidation of an electron donor system comprising ascorbate, N,N,N',N'-tetramethyl-p-phenylenediamine, and horse heart cytochrome c resulted in a membrane potential (Deltapsi) of -60 mV, a pH gradient of -36 mV, and an l-leucine accumulation of 76-fold (Deltamu(Leu)/F = 108 mV). Leucine uptake in hybrid membranes in which a Deltapsi, DeltapH, sodium ion gradient, or a combination of these was imposed artificially revealed that both components of the proton motive force (Deltap) could drive leucine uptake but that a chemical sodium gradient could not. Kinetic analysis of leucine (valine) transport indicated three secondary transport systems with K(t) values of 1.7 (0.8) mM, 4.3 (5.9) muM, and 65 (29) nM, respectively. l-Leucine transport via the high-affinity leucine transport system (K(t) = 4.3 muM) was competitively inhibited by l-valine and l-isoleucine (K(i) and K(t) values were similar), demonstrating that the transport system translocates branched-chain amino acids. Similar studies with these hybrid membranes indicated the presence of high-affinity secondary transport systems for 10 other amino acids.

Cholecystojejunostomy complicated by massive hemocholecyst.

Diagnostic arteriography was performed in two patients with acute gastrointestinal hemorrhage in whom palliative cholecystojejunostomies had recently been performed. Bleeding was found to be coming from the cystic arteries in both cases. In patients with gastrointestinal hemorrhage in whom there is a history of a cholecystojejunostomy, hemocholecyst should be considered and a hepatic artery injection included in the angiographic study.