Showing papers on "Leuconostoc published in 1997"

Controlled gene expression systems for lactic acid bacteria: transferable nisin-inducible expression cassettes for Lactococcus, Leuconostoc, and Lactobacillus spp.

Abstract: A transferable dual-plasmid inducible gene expression system for use in lactic acid bacteria that is based on the autoregulatory properties of the antimicrobial peptide nisin produced by Lactococcus lactis was developed. Introduction of the two plasmids allowed nisin-inducible gene expression in Lactococcus lactis MG1363, Leuconostoc lactis NZ6091, and Lactobacillus helveticus CNRZ32. Typically, the beta-glucuronidase activity (used as a reporter in this study) remained below the detection limits under noninducing conditions and could be raised to high levels, by addition of subinhibitory amounts of nisin to the growth medium, while exhibiting a linear dose-response relationship. These results demonstrate that the nisin-inducible system can be functionally implemented in lactic acid bacteria other than Lactococcus lactis.

Controlled Gene Expression Systems for Lactic Acid Bacteria : Transferable Nisin-Inducible Expression Cassettes for Lactococcus, Leuconostoc, and Lactobacillus spp.

Abstract: A transferable dual-plasmid inducible gene expression system for use in lactic acid bacteria that is based on the autoregulatory properties of the antimicrobial peptide nisin produced by Lactococcus lactis was developed. Introduction of the two plasmids allowed nisin-inducible gene expression in Lactococcus lactis MG1363, Leuconostoc lactis NZ6091, and Lactobacillus helveticus CNRZ32. Typically, the β-glucuronidase activity (used as a reporter in this study) remained below the detection limits under noninducing conditions and could be raised to high levels, by addition of subinhibitory amounts of nisin to the growth medium, while exhibiting a linear dose-response relationship. These results demonstrate that the nisin-inducible system can be functionally implemented in lactic acid bacteria other than Lactococcus lactis.

The role of transport processes in survival of lactic acid bacteria. Energy transduction and multidrug resistance

Abstract: Lactic acid bacteria play an essential role in many food fermentation processes. They are anaerobic organisms which obtain their metabolic energy by substrate phosphorylation. In addition three secondary energy transducing processes can contribute to the generation of a proton motive force: proton/substrate symport as in lactic acid excretion, electrogenic precursor/product exchange as in malolactic and citrolactic fermentation and histidine/histamine exchange, and electrogenic uniport as in malate and citrate uptake in Leuconostoc oenos. In several of these processes additional H+ consumption occurs during metabolism leading to the generation of a pH gradient, internally alkaline. Lactic acid bacteria have also developed multidrug resistance systems. In Lactococcus lactis three toxin excretion systems have been characterized: cationic toxins can be excreted by a toxin/proton antiport system and by an ABC-transporter. This cationic ABC-transporter has surprisingly high structural and functional analogy with the human MDR1-(P-glycoprotein). For anions an ATP-driven ABC-like excretion systems exist.

Growth and energetics of Leuconostoc mesenteroides NRRL B-1299 during metabolism of various sugars and their consequences for dextransucrase production.

Abstract: The metabolic and energetic properties of Leuconostoc mesenteroides have been examined with the goal of better understanding the parameters which affect dextransucrase activity and hence allowing the development of strategies for improved dextransucrase production. Glucose and fructose support equivalent specific growth rates (0.6 h-1) under aerobic conditions, but glucose leads to a better biomass yield in anaerobiosis. Both sugars are phosphorylated by specific hexokinases and catabolized through the heterofermentative phosphoketolase pathway. During sucrose-grown cultures, a large fraction of sucrose is converted outside the cell by dextransucrase into dextran and fructose and does not support growth. The other fraction enters the cell, where it is phosphorylated by an inducible sucrose phosphorylase and converted to glucose-6-phosphate (G-6-P) by a constitutive phosphoglucomutase and to heterofermentative products (lactate, acetate, and ethanol). Sucrose supports a higher growth rate (0.98 h-1) than the monosaccharides. When fructose is not consumed simultaneously with G-1-P, the biomass yield relative to ATP is high (16.8 mol of ATP.mol of sucrose-1), and dextransucrase production is directly proportional to growth. However, when the fructose moiety is used, a sink of energy is observed, and dextransucrase production is no longer correlated with growth. As a consequence, fructose catabolism must be avoided to improve the amount of dextransucrase synthesized.

A small heat shock protein from Leuconostoc oenos induced by multiple stresses and during stationary growth phase

Abstract: In Leuconostoc oenos, a malolactic bacterium, the synthesis of a stress protein called LO18 with an apparent molecular mass of 18 kDa was greatly induced after heat (42 degrees C), acid (pH 3) or ethanolic (12% (v/v)) shocks. Moreover, the LO18 protein synthesis was induced in stationary growth phase and was detected for a long time (30 h) during this growth phase. Significant identity was found between the N-terminal parts of the LO18 protein and the Hsp18 from Clostridium acetobutylicum suggesting that LO18 protein belongs to the family of small heat shock proteins conserved in prokaryotic and eukaryotic cells.

Multiple bacteriocin production by Leuconostoc mesenteroides TA33a and other Leuconostoc/Weissella strains.

Abstract: Leuconostoc (Lc.) mesenteroides TA33a produced three bacteriocins with different inhibitory activity spectra. Bacteriocins were purified by adsorption/desorption from producer cells and reverse phase high-performance liquid chromatography. Leucocin C-TA33a, a novel bacteriocin with a predicted molecular mass of 4598 Da, inhibited Listeria and other lactic acid bacteria (LAB). Leucocin B-TA33a has a predicted molecular mass of 3466 Da, with activity against Leuconostoc/Weissella (W.) strains, and appears similar to mesenterocin 52B and dextranicin 24, while leucocin A-TA33a, which also inhibited Listeria and other LAB strains, is identical to leucocin A-UAL 187. A survey of other known bacteriocin-producing Leuconostoc/Weissella strains for the presence of the three different bacteriocins revealed that production of leucocin A-, B- and C-type bacteriocins was widespread. Lc. carnosum LA54a, W. paramesenteroides LA7a, and Lc. gelidum UAL 187-22 produced all three bacteriocins, whereas W. paramesenteroides OX and Lc. carnosum TA11a produced only leucocin A- and B-type bacteriocins.

In vitro antibacterial activity of LY333328, a new semisynthetic glycopeptide.

Abstract: LY333328 is a semisynthetic N-alkyl derivative of LY264826, a naturally occurring structural analog of vancomycin. LY333328 was evaluated for its in vitro inhibitory and bactericidal activities in comparison with those of the two currently available glycopeptides (vancomycin and teicoplanin). Glycopeptide-susceptible test strains included a total of 311 isolates (most of clinical origin) from the genera Staphylococcus, Enterococcus, Streptococcus, Aerococcus, Gemella, Lactococcus, Listeria, Corynebacterium, and Clostridium. Test strains resistant or intermediate to vancomycin and/or teicoplanin included 56 clinical isolates of Enterococcus (of the VanA, VanB, and VanC phenotypes) and 32 clinical isolates of Staphylococcus (S. haemolyticus, S. epidermidis, and S. aureus), 31 strains of gram-positive genera outside the spectrum of activity of vancomycin (Leuconostoc, Pediococcus, Lactobacillus, and Erysipelothrix), and laboratory-derived organisms obtained after exposure of susceptible Staphylococcus isolates to teicoplanin (6 strains) or laboratory-derived organisms with resistance determinants received from VanA enterococci (2 Enterococcus and 25 Listeria transconjugants). LY333328 was highly active against staphylococci, enterococci, and listeriae (whether they were clinical or laboratory-derived strains) resistant to the currently available glycopeptides. In particular, the MICs of LY333328 did not vary substantially between teicoplanin-susceptible and teicoplanin-resistant staphylococci and between vancomycin-susceptible and vancomycin-resistant enterococci. LY333328 demonstrated fairly good inhibitory activity even against most strains of Leuconostoc, Pediococcus, and Erysipelothrix (MIC range, 1 to 8 microg/ml), whereas it proved less active (although much more active than vancomycin or teicoplanin) against Lactobacillus strains. In minimal bactericidal concentration (MBC) and time-kill studies, LY333328 demonstrated excellent bactericidal activity; enterococci, in particular, which were largely tolerant of vancomycin and teicoplanin, were uniformly killed by LY333328, with MBC-to-MIC ratios of 4 to 8 for most vancomycin-susceptible and vancomycin-resistant strains. In attempts to select for resistant clones, no survivors stably growing in the presence of 10 microg of LY333328 per ml were obtained from the Staphylococcus and Enterococcus test strains exposed to the drug.

Characterization of strains of Leuconostoc mesenteroides by analysis of soluble whole-cell protein pattern, DNA fingerprinting and restriction of ribosomal DNA.

Abstract: Of 215 leuconostocs isolated from field grass, natural whey cultures and water-buffalo milk, 178 were identified as Leuconostoc mesenteroides ssp. mesenteroides while 37 strains could not be identified. Biochemical characterization allowed seven groups to be defined. Representative strains of each group and different habitat and nine reference strains were selected for further analyses. Protein profiles appeared suitable for species discrimination, but did not differentiate between the three subspecies of Leuc. mesenteroides. The technique also showed some differences among equivocal strains. DNA fingerprinting for most strains of Leuc. mesenteroides ssp. mesenteroides examined showed a different restriction pattern from that of the type strain. Ribotyping was not useful for discriminating species and subspecies of the genus Leuconostoc: Leuc. mesenteroides ssp. mesenteroides and ssp. dextranicum showed the same ribopattern as Leuc. lactis while Leuc. mesenteroides ssp. cremoris exhibited a pattern distinct from all the other species examined. On the basis of ARDRA-PCR, two main groups could be distinguished: the larger group included Leuc. mesenteroides, Leuc. lactis, Leuc. pseudomesenteroides and some unidentifiable strains; the second one included Leuc. citreum, Leuc. fallax, Weissella paramesenteroides and some unidentified strains.

Microbial population and biochemical changes in fermenting finger millet (Eleusine coracana)

Abstract: Natural fermentation of finger millet (Eleusine coracana) was carried out for 48 h. Microbiological and chemical analysis was performed throughout the fermentation process. The fermentation was heterolactic dominated by lactic acid bacteria accompanied by the production of lactic and acetic acids with decrease in pH and increase in titratable acidity. The microbial population increased until 18 to 24 h accompanied by a rapid decrease in total and reducing sugars. The microflora stabilized between 24 and 48 h, during which time the total and α-amylase activities increased with accumulation of sugars. Total free amino acids also increased. Yeast counts were low and moulds and coliforms were absent. Repeated fermentations showed consistency in the qualitative and quantitative changes in microflora. Five predominant types of bacteria, strains belonging to Leuconostoc, Pediococcus and Lactobacillus were identified. Of these only one type, Pediococcus, dominated (>80%) in the latter half of fermentation.

Aptitude of cheese bacteria for volatile S-methyl thioester synthesis. II. Comparison of coryneform bacteria, Micrococcaceae and some lactic acid bacteria starters

Abstract: Various strains of coryneform bacteria, Micrococcaceae and commercial starters of Lactococcus lactis and Leuconostoc were compared for their aptitude to form S-methyl thioesters. Resting cells were incubated with methanethiol alone at pH 7 and in conjunction with a mixture of straight, branched and hydroxy short-chain fatty acids up to C6 at pH 7 and 5. Results showed that all the strains synthesized at least S-methyl thioacetate, with strains that were low and high producers in each group. This is the only thioester formed in small amount by Leuconostoc. Brevibacterium linens (six strains) and Micrococcaceae (five strains) were able to form branched-chain thioesters especially from their intracellular fatty acids at neutral pH, and straight-chain thioesters mostly from exogenous fatty acids at acid pH. Coryneform bacteria other than B. linens (four strains) and L. lactis (four starters) synthesized thioesters up to S-methyl thiobutyrate from endogenous or exogenous fatty acids but not branched-chain ones, except for one starter which formed a very little thioisovalerate. Some particular effects of pH and added fatty acids revealed differences between species or strains in their specific enzymatic systems.

Inhibition of malolactic fermentation by cryotolerant yeasts

Abstract: White wines produced by some cryotolerant strains of Saccharomyces cerevisiae are more resistant to malolactic fermentation than those produced by normal strains: e.g. for two months of storage, the wines, inoculated with Leuconostoc oenos or Lactobacillus plantarum, were fully stabilized with levels of 51-65 mg total SO 2 /l and 5.70-5.75 g titratable acidity/l. The use of these yeasts in wine-making can decrease the quantities of sulfites added to stabilize wines.

Semiquantitation of cooperativity in binding of vancomycin-group antibiotics to vancomycin-susceptible and -resistant organisms.

Abstract: The association of vancomycin group antibiotics with the growing bacterial cell wall was investigated by using the cell wall precursor analog di-N-acetyl-Lys-D-Ala-D-Ala in competition binding experiments. The affinities of the antibiotics for the -D-Ala-D-Ala-containing cell wall precursors of Bacillus subtilis ATCC 6633 (a model for vancomycin-susceptible gram-positive bacteria) and for the -D-Ala-D-Lac-containing cell wall precursors of Leuconostoc mesenteroides (a model for vancomycin-resistant strains of Enterococcus faecium and Enterococcus faecalis) were determined by a whole-cell assay. The binding of strongly dimerizing antibiotics such as eremomycin to the bacterial surface was thus shown to be enhanced by up to 2 orders of magnitude (relative to the binding in free solution) by the chelate effect, whereas weakly dimerizing antibiotics like vancomycin and antibiotics carrying lipid tails (teicoplanin) benefited less (ca. 1 order of magnitude). The affinity measured in this way correlates well with the MIC of the antibiotic, and a consequence of this is that future design of semisynthetic vancomycin-group antibiotics should attempt to incorporate chelate effect-enhancing structural features.

Identification and sequence analysis of the region encoding the site-specific integration system from Leuconostoc œnos (Œnococcus œni) temperate bacteriophage φ10MC

Abstract: Malolactic fermentation conducted by Leuconostoc œnos is an essential step in winemaking. L. œnos bacteriophages are thought to be responsible for fermentation failures, yet they have received little attention. The integration system of bacteriophage φ10MC in the LOF111 L. œnos strain chromosome was studied and a 1456 bp phage DNA fragment was cloned and sequenced. An open reading frame (int) showing homology with several temperate bacteriophage integrases was located upstream of the phage attachment site (attP). This organisation is comparable to other phage site-specific recombination systems. The same bacterial attachment site (attB) located in a tRNAleu gene was found in all 15 L. œnos strains studied and was involved in φ10MC integration in the bacterial chromosome.

Proteolytic activity of Leuconostoc oenos

Abstract: The proteolytic activity of Leuconostoc oenos protease on white wine proteins and polypeptides was studied. Comparison of the peptide profiles before and after protease action demonstrated the presence of two new and an increase in two other peptide peaks. In total 56.7 mg l−1 of peptides was liberated by action of the Lc.oenos proteases. Essential amino acids for Lc. oenos growth were liberated as free amino acids, and arginine, which has a stimulatory effect on Lc. oenos growth, was quantitatively the more important amino acid obtained by protease activity. Thus proteolytic activity serves to provide the cells with essential growth factors.

Nutritional requirements of Leuconostoc mesenteroides subsp. mesenteroides and subsp. dextranicum for growth in milk

Abstract: Growth of Leuconostoc mesenteroides in milk was studied with respect to the proteinase and peptidase activities of the strains and their nutritional requirements. L. mesenteroides grew poorly in milk since none of the 14 strains studied exceeded 5 x 10 8 cfu/ml at the end of growth. Few strains displayed proteinase activity, and this did not contribute much to growth. The pattern of peptidase activities varied with the strain. Nitrogen starvation and a high requirement for Mn 2+ were involved in the cause of growth deficiencies. Addition of amino acids, 50 mg Mg 2+ /l and 0.08-0.49 mg Mn 2+ /l stimulated growth of most Leuconostoc strains up to 5 x 10 8 cfu/ml. Addition of 5 g glucose/l to milk containing amino acids, Mg 2+ and Mn 2+ or yeast extract stimulated the growth of seven and eight strains respectively up to 10 9 cfu/ml. No growth advantage was found in a N 2 atmosphere. However, the addition of small amounts of Mn 2+ to milk suppressed the inhibitory effect of aeration on the growth of L. mesenteroides UD23, suggesting a protective role of Mn 2+ against O 2 toxicity.

Role of adventitious microflora in proteolysis and lipolysis of Serra cheese: preliminary screening

Abstract: Six different types of bacteria (five strains of lactic acid bacterium and one strain of coliform) isolated from 35-day-old Serra cheese were assayed for proteolytic and lipolytic activities on milk agar and tributyrin agar, respectively. Peptidase and lipase activities were further studied via analytical assaying of free amino acids by spectrophotometry and of free fatty acids by HPLC in in vitro curdled milk (previously prepared from heat-sterilized ovine milk coagulated with thistle flower) subject to ripening for 21 days at 5 °C and 95% relative humidity. Leuconostoc mesenteroides ssp. mesenteroides/dextranicum and Lactococcus lactis ssp. lactis displayed significant proteinase and peptidase activities, where Leuconostoc lactis and Enterococcus faecium only exhibited peptidase activity. Leuc. mesenteroides ssp. mesenteroides/dextranicum, Ent. faecium, and L. lactis ssp. lactis only showed lipase activity on milk fat after a long incubation period. Short- and medium-chain fatty acid residues were released preferentially by microbial lipases, although long-chain fatty acids were also significantly released by lipases from Leuc. mesenteroides ssp. mesenteroides/ dextranicum. Lactobacillus paracasei ssp. paracasei and Hafnia alvei did not display measurable protease, peptidase, or lipase activities. In view of their hydrolase activities, it is suggested that L. lactis ssp. lactis and Leuconostoc spp. (with possible incorporation of Ent. faecium) are a potential mixed-strain starter for Serra cheesemaking.

Classification of isolates originating from Kimchi using carbon-source utilization patterns

Abstract: One hundred and eighty two lactic acid bacteria, isolated mainly from kimchi, including reference strains were examined for their ability to utilize 95 carbon sources. The test strains were assigned to 5 major, 1 minor and 12 single-membered clusters based on the , UPGMA algorithm (at similarity of ). These aggregate clusters were equivalent to the genus Leuconostoc (aggregate cluster M and N), the genus Lactobacillus (aggregate cluster Q and R), and the genera Lactobacillus and Leuconostoc (aggregate cluster O and P) according to the database of the Biolog system. This study demonstrates that rapid identification and classification of isolates originating from kimchi can be achieved on the basis of such carbon source utilization tests.

Leuconostoc bacteremia after liver transplantation : another cause of vancomycin resistant gram-positive infection

Abstract: Leuconostoc sp. are gram-positive bacteria intrinsically resistant to vancomycin, which can be confused with streptococci based on routine microbiological-characteristics. Infections secondary to Leuconostoc are uncommon, and usually affect patients with underlying diseases, prior use of vancomycin and those with central lines. The most common clinical presentation is fever secondary to a central line infection. We report the first case of Leuconostoc infection in a solid organ transplant recipient. The patient developed Leuconostoc bacteremia secondary to peritonitis, 60 d after undergoing liver transplantation. He was treated with clindamycin, gentamicin and underwent surgical debridement, but succumbed to other complications.

Detection and partial characterization of a bacteriocin produced by Carnobacterium piscicola 213

Abstract: BLIS 213, is a bacteriocin-like inhibitory substance produced by Carnobacterium piscicola 213. It is active against Carnobacterium, Enterococcus and Listeria spp. No activity was observed against tested Lactobacillus, Lactococcus, Leuconostoc and Pediococcus strains, nor against Gram-negative bacteria. The BLIS 213 activity was inactivated by several proteolytic enzymes. It was heat resistant (121°C for 20 min), and stable over a pH range of 2–8. Activity was determined by a dilution micromethod; it was increased after SDS treatment. A mutant strain which lacks bacteriocin production was isolated and designated as Carnobacterium piscicola 213a. It had the same phenotypic and biochemical properties as the parent strain, and was not sensitive to bacteriocin activity. The apparent molecular weight of the bacteriocin in the crude extract was greater than 10 kDa. It was about 6 kDa after SDS-PAGE of a partially purified bacteriocin by adsorption on producer cells. The isoelectric point of the BLIS 213 was around 9.3.

Pleural empyema caused by Leuconostoc spp.

Abstract: A rare case of pleural empyema caused by Leuconostoc spp. is reported. The patient was treated successfully with clindamycin. To our knowledge this is the first reported case of pleural empyema caused by Leuconostoc spp. in a patient with characteristic predisposing factors, such as a serious underlying disease, previous vancomycin therapy and thoracic access device. Our case illustrates that Leuconostoc spp. can cause pleural infection as further evidence of its human pathogenecity.

Leuconostoc spp. Septicaemia in a Child with Short Bowel Syndrome

Abstract: Septicaemia caused by the vancomycin-resistant Gram-positive bacteria Leuconostoc spp. is uncommon. We report a case of Leuconostoc spp. septicaemia in a child with short bowel syndrome fed through a central venous catheter and a gastrostomy. Leuconostoc spp. were isolated from several blood cultures. Despite several courses of antibiotics the fever continued and her condition deteriorated. After removal of the thrombotized central venous catheter her condition improved. Leuconostoc spp. was isolated from the thrombotic masses.

Plasmid-associated bacteriocin production by Leuconostoc sp. LAB145-3A isolated from Kimchi

Abstract: Leuconostoc sp LAB145-3A isolated from kimchi produced a bacteriocin which was active against food pathogens, such as Listeria monocytogenes, Enterococcus faecalis, and E faecium Bacteriocin production occurred during the early exponential phase of growth and was stable upto the late stationary phase of growth Optimum conditions for bacteriocin production were with an initial pH of 70 The bacteriocin of LAB145-3A was sensitive to proteases, but stable for solvents, pH change and heat treatment It was stable even at autoclaving temperature for 15 min The bacteriocin exhibited a bactericidal mode of action against Lactobacillus curvatus LAB170-12 The bacteriocin produced by Leuconostoc sp LAB145-3A was purified by CM-cellulose cation exchange column chromatography and Sephadex G-50 gel filtration The purification resulted in an approximate 10,000-fold increase in the specific activity Approximately 4% of the initial activity was recovered Purified bacteriocin exhibited a single band on the SDS-PAGE with an apparent molecular weight of 4,400 daltons This bacteriocin was named leucocin K Leuconostoc sp LAB145-3A had two residential plasmids with molecular sizes of 23 kb and 48 kb A comparison of plasmid profiles between LAB145-3A and its mutants revealed that the 23 kb plasmid (pCA23) was responsible for bacteriocin production and immunity to the bacteriocin in Leuconostoc sp LAB145-3A

Growth and metabolism of Leuconostoc oenos in synthetic media

Abstract: The influence of nitrogen compounds on the growth of Leuconostoc oenos m isolated from Argentinian wine was investigated in complex and synthetic media supplemented or not with L-malic and citric acids. L-malic acid increased the growth of the strain in complex and synthetic media and citric acid only do it in the synthetic medium. Leuconostoc oenos m was prototrophic for all vitamins and no growth was observed when the essential amino acids L-asparagine, L-isoleucine, L-tyrosine and L-cysteine and different combinations of them were successively omitted in the synthetic medium. Both organic acids allowed the growth of the strain in absence of L-asparagine and L-isoleucine, L-asparagine and L-cysteine or L-isoleucine and L-cysteine. In this condition an imbalance of carbon flux was observed and L-malic acid was completely metabolized in L-lactic acid.

The Lactic Acid Bacteria

Abstract: The lactic acid bacteria (LAB) isolated from wine are located in two families and three genera (with several species and strains). The Lactobacillaceae, represented by the genus Lactobacillus, includes rod-shaped Gram-positive species and their respective strains (see Fig. 1-1), whereas the Streptococcaceae represented by the genera Pediococcus and Leuconostoc, includes Gram-positive coccoid- or coccobacilloid-shaped isolates (see Figs. 1-2 and 1-3). Both groups may grow as somewhat characteristic aggregations of cells. These may include chains of lenticular or sausage-shaped cells, in the case of Leuconostoc oenos, filamentous chains (Lactobacillus fructivorans), and tetrads that result from division in two planes (Pediococcus damnosus).