[Difference in nitrate reductase activity between Veillonella alcalescens and Veillonella parcula (author's transl)].
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Nitrate Reductases↗
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Lethality for mice and chick embryos, pyrogenicity in rabbits and ability to gelate lysate from amoebocytes of Limulus polyphemus by lipopolysaccharides from Bacteroides, Fusobacterium and Veillonella.
Phenol-water extracted lipopolysaccharides (LPS) from Veillonella, Fusobacterium nucleatum, Bacteroides fragilis and Bacteroides melaninogenicus were lethal for mice and 11-days-old chick embryos, pyrogenic in rabbits, and gelated Limulus amoebocyte lysate. Mouse lethality was considerably enhanced by actinomycin-D. In all test systems the endotoxin activity of Veillonella and Fusocbacterium LPS was comparable to that of LPS from Salmonella enteritidis, which was included as a reference endotoxin. The endotoxicity of the Bacteroides LPS was very low. While nanograms of the Veillonella and Fusobacterium LPS killed the chick embryos and gelated the Limulus lysates, microgram amounts of the Bacteroides LPS were needed to give positive reaction in the same test systems. As much as 74 microgram of the most active B. fragilis LPS were required to give a typical biphasic fever response in rabbits. A significant correlation was found between all test results (r = 0.90-0.98, p less than 0.001).
Animals↗
Adherence of Veillonella species mediated by extracellular glucosyltransferase from Streptococcus salivarius.
The effect of extracellular products from Streptococcus salivarius on sucrose-dependent adherence to smooth surfaces by other oral bacteria was studied in vitro. Strains of Streptococcus mitis, Streptococcus pyogenes, and Veillonella parvula without innate ability to adhere to a steel wire were able to do so when incubated with sucrose and cell-free culture fluid from S. salivarius strains 9759, 25975, CNII, and MEPI. These culture fluids synthesized more adherent material and water-insoluble glucan than those from Streptococcus mutans C67-1 and seven other S. salivarius strains. Among the S. salivarius strains, glucosyltransferase (GT; dextransucrase, EC 2.4.1.5) activity varied more than 100-fold. Cells of Veillonella and S. mitis S3 that had been incubated in culture fluids from S. salivarius 25975 and 9759, respectively, and then washed adhered upon subsequent incubation with sucrose. This was due to adsorbed GT because (i) the adherence was sensitive to dextranase; (ii) it was observed only with the high-GT culture fluids; (iii) it was dependent on sucrose; and (iv) the washed Veillonella cells synthesized glucan, but not fructan, from sucrose. These results suggest that sucrose-dependent adherence of bacteria without such innate ability can be mediated by (i) entrapment in insoluble glucan synthesized by S. salivarius culture fluids, and (ii) prior adsorption of GT from S. salivarius culture fluids. The possibility that GT formed by high-yield strains of S. salivarius is distributed through the mouth by the action of salivary flow and contributes to sucrose-dependent adherence and plaque formation is considered.
Adsorption↗
Rapid screening of Veillonella by ultraviolet fluorescence.
Among 51 strains of anaerobic gram-negative cocci belonging to the family Veillonellaceae, all strains of Veillonella (V. parvula and V. alcalescens) displayed red fluorescence under long-wave (366 nm) ultraviolet light, whereas no Acidaminococcus or Megasphaera demonstrated fluorescence. In contrast to Bacteroides melaninogenicus, growth of Veillonella does not require hemin and menadione, and flourescence is rapidly lost upon exposure to air. The fluorescent component of a strain of V. parvula examined could not be extracted in solution with water, ether, methanol, or chloroform, but was readily extracted with 0.4 N NaOH. Spectrophotofluorometrically, the fluorescence maximum of this extract was 660 nm with an excitation maximum of 300 nm, when measured at pH 7.2 and 25 C. Coupled with the Gram stain, ultraviolet fluorescence may be a useful tool for rapid screening of Veillonella and is particularly helpful for detection and, isolation of this organism from mixed culture.
Air↗
[Gas chromatography analysis of volatile monocarboxylic aliphatic acids (C2 to C6) of 15 strains of Veillonella of oral origin].
A qualitative and quantitative study has been carried out on 15 strains of the Veillonella genus, isolated in the oral cavity. Following two methods of preparation of samples for injection in a chromatograph GL, we have identified among the volatil monocarboxylic aliphatic acids from C2 to C6 the glucose fermentation products of these different strains. With the same methods, we studied in parallel these products from strains A.T.C.C. 10790-17444 (Veillonella parvula) and 17445-17446 and 17447 (Veillonella alcalescens). The results, despite the diversity of origin of all these strains, based on physiological and biochemical characteristics, confirm that volatil monocarboxylic aliphatic acids are characteristic of a genus specificity and not of a species. The presence of acetic acid, proprionic acid and iso-valeric acid was shown
Chromatography, Gas↗
Rabbit polymorphonuclear leukocyte migration in vitro in response to lipopolysaccharides from Bacteroides, Fusobacterium and Veillonella.
Puriified lipopolysaccharides (LPS) from strains of Bacteroides, Fusobacterium and Veillonella incubated with guinea pig serum, were tested for chemotatic activity against rabbit polymorphonuclear leukocytes (PMNs) in modified Boyden chambers. Comparisons were made to a Salmonella LPS (S. enteriditis S-795). Submicrogram amounts of LPS induced positive chemotaxis, and a typical dose-response relationship up to certain dose levels was observed. The difference in chemotactic activity between the Veillonella LPS and LPS-S-795 was not statistically significant. The Fusobacterium LPS showed either a non-significant or a highly significantly lower chemotatic capacity than LPS-S-795. The Bacteroides LPS were also clearly chemotactic, but considerable less when compared to the Salmonella LPS. When serum was not added, the LPS preparation showed no chemotactic activity.
Animals↗
Rabbit polymorphonuclear leukocyte migration in vivo in response to lipopolysaccharides from Bacteroides, Fusobacterium and Veillonella.
Subcutaneously implanted chambers in rabbits were used for testing the migration of polymorphonuclear leukocytes in response to injected LPS isolated from strains of Bacteroides, Fusobacterium and Veillonella. A salmonella LPS was used as reference endotoxin. No differnece in chemotactic activity between the Veillonella LPS and LPS from Salmoneila was found. Fusobacterium LPS whoed insignificantly lower chemotactic capacity than the Salmonella LPS. The Bacteroides LPS were all significantly less chemotactic than the reference endotoxin. An insignificant correlation between the amount of exudate aspirated from the chambers 5 h after injection of the different LPS preparations and the number of leukocytes per microliter of exudate was found.
Animals↗
Chemotypes of Veillonella lipopolysaccharides.
Lipopolysaccharides (LPS) were isolated by phenol-water extraction from 34 strains of Veillonella, and examined by paper chromatography and colorimetric methods for the presence of neutral sugars, amino sugars and 2-keto-3-deoxy-octonate (KDO). Several preparations were also examined for neutral sugars by gas liquid chromatography. The LPS had in common glucosamine, galactosamine, L-glycero-D-manno-heptose glucose and KDO. Most LPS contained galactose, and a few rhamnose. D-glycero-D-manno-heptose was found in LPS from one of the strains. Based on the sugar composition of the LPS, the Veillonella strains could be classified into four chemotypes.
Chromatography, Gas↗
ATP formation associated with fumarate and nitrate reduction in growing cultures of Veillonella alcalescens.
Molar growth yields, fermentation balances and enzyme activities were measured in Veillonella alcalescens grown anaerobically with different substrates in the absence or presence of fumarate or nitrate. The molar growth yields on malate (14.3 g dry wt bacteria/mole substrate) and citrate (19.3) were higher than that on lactate (8.6). The molar growth yield on lactate was increased to 15.5 or 19.8 by the addition of fumarate or nitrate, respectively, to the growth medium, and the molar growth yield on citrate was increased to 25.3 by addition of nitrate. Active growth on pyruvate was only observed in the presence of nitrate, and the molar growth yield was 25.5. From fermentation balances and fermentation systems similar YATP values (g dry wt bacteria/mole ATP) were calculated for all substrates or mixtures of substrates assuming that one mole of ATP is generated at the electron transport from pyruvate, NADH and NADPH to nitrate or fumarate whereas ATP is not produced in the electron transport from lactate to fumarate or nitrate, and, therefore, this assumption was considered to reflect the actual situation. The mean YATP value at a doubling time of 1 h was 16.5 g dry wt bacteria/mole ATP for growth without an added hydrogen acceptor, 14.4 for growth with fumarate, and 14.2 for growth with nitrate.
Adenosine Triphosphate↗
Studies by electron-paramagnetic-resonance spectroscopy on the mechanism of action of xanthine dehydrogenase from Veillonella alcalescens.
E.p.r- (electron-paramagnetic-resonance) spectroscopy was used to compare chemical environment and reactivity of molybdenum, flavin and iron-sulphur centres in the enzyme xanthine dehydrogenase from Veillonella alcalescens (Micrococcus lactilyticus) with those of the corresponding centres in milk xanthine oxidase. The dehydrogenase is frequently contaminated with small but variable amounts of a species resistant to oxidation and giving a new molybdenum (V) e.p.r. signal, "Resting I". There is also a "desulpho" form of the enzyme giving a Slow Mo(V) signal, indistinguishable from that of the milk enzyme. Molybdenum of the active enzyme behaves in a manner analogous to that of the milk enzyme, giving a Rapid Mo(V) signal on partial reduction with substrates or dithionite. Detailed comparison shows that molybdenum in each enzyme must have the same ligand atoms arranged in the same manner. As with the milk enzyme, complex-formation between reduced dehydrogenase and purine substrate molecules, presumably interacting at the normal substrate-binding site, modifies the Rapid signal, confirming that such substrates interact near molybdenum. The dehydrogenase-flavin semiquinone signal is identical with that of the oxidase but, in contrast, there is only one iron-sulphur signal. The latter gives an e.p.r. spectrum similar to that of aldehyde oxidase.
Animals↗
Properties of membrane adenosine triphosphatase of the obligately anaerobic bacterium Veillonella alcalescens.
Some properties of membrane ATPase activity in Veillonella alcalescens were examined. Mg2+ is required for the activity of the enzyme, and Ca2+ also activates the enzyme to some degree. Of the nucleotide triphosphates, GTP and ITP were hydrolyzed to a lesser extent than ATP. The apparent Km for ATP hydrolysis was 0.25 to 0.63 mM. ADP inhibited the enzyme and the kinetic data of its inhibition showed that the presence of ADP resulted in positive cooperativity. The enzyme activity was strongly inhibited by DCCD, azide, fusidic acid and the antibody to purified soluble ATPase from the thermophilic bacterium PS3. Oligomycin, dinitrophenol, and ouabain showed no significant effect.
Adenosine Triphosphatases↗
Human complement activation by lipopolysaccharides from bacteroides oralis, fusobacterium nucleatum, and veillonella parvula.
The properties of different lipopolysaccharide (LPS) preparations to induce C3 conversion in human serum was studied by means of crossed immunoelectrophoresis. C3 conversion by the alternative pathway was evaluated after calcium depletion, and lipid A-dependent activation was measured by means of inhibition with polymyxin B sulfate. LPS from Bacteroides oralis converted Co mainly via the alternative pathway, whereas LPS from Fusobacterium nucleatum and Veillonella parvula const pronounced lipid A-dependent conversion. The results are discussed in relation to the chemical composition of the LPS preparations.
Adult↗
Amino acid transport in membrane vesicles of obligately anaerobic Veillonella alcalescens.
Membrane vesicles of Veillonella alcalescens, grown in the presence of L-lactate and KNO-3, actively transport amino acids under anaerobic conditions in the presence of several electron donors and the electron acceptor nitrate. The highest initial rates of uptake are obtained with L-lactate, followed by reduced nicotinamide adenine dinucleotide, glycerol-1-phosphate, formate, and L-malate.. The membrane vesicles contain the dehydrogenases for these electron donors, and these enzymes are coupled with nitrate reductase. In membrane vesicles from cells, grown in the presence of nitrate, the dehydrogenases are not coupled with fumarate reducatase, and anaerobic transport of amino acids does not occur with fumarate as electron acceptor. Under aerobic conditions none of the physiological electron donors can energize transport. However, a high rate of uptake is observed with the electron donor system ascorbate-phenazine metho-sulfate. This electron donor system also effectively energizes transport under anaerobicconditions in the presence of the electron acceptor nitrate.
Aerobiosis↗
Purification and regulatory properties of pyruvate kinase from Veillonella parvula.
The nonglycolytic, anaerobic organism Veillonella parvula M4 has been shown to contain an active pyruvate kinase. The enzyme was purified 126-fold and was shown by disc-gel electrophoresis to contain only two faint contaminating bands. The purified enzyme had a pH optimum of 7.0 in the forward direction and exhibited sigmoidal kinetics at varying concentrations o-f phosphoenol pyruvate (PEP), adenosine 5'-monophosphate (AMP), and Mg-2+ ions with S0.5 values of 1.5, 2.0, and 2.4 mM, respectively. Substrate inhibition was observed above 4 m PEP. Hill plots gave slope values (n) of 4.4 (PEP), 2.8 (adenosine 5'-diphosphate), and 2.0 (Mg-2+), indicating a high degree of cooperativity. The enzyme was inhibited non-competitively by adenosine 5'-triphosphate (Ki = 3.4 mM), and this inhibition was only slightly affected by increasing concentration of Mg-2+ ions to 30 mM. Competitive inhibition was observed with 3-phosphoglycerate, malate, and 2,3-diphosphoglycerate but only at higher inhibitor concentrations. The enzyme was activated by glucose-6-phosphate (P), fructose-6-P, fructose-1,6-diphosphate (P2), dihydroxyacetone-P, and AMP; the Hill coefficients were 2.2, 1.8, 1.5, 2.1, and 2.0, respectively. The presence of each these metabolites caused substrate velocity curves to change from sigmoidal to hyperbolic curves, and each was accompanied by an increase in the maximum activity, e.g., AMP greater than fructose-1,6-P2 greater than dihydroxyacetone-P greater than glucose-6-P greater than fructose-6-P. The activation constants for fructose-1,6-P2, AMP, and glucose-6-P were 0.3, 1.1, and 5.3 mM, respectively. The effect of 5 mM fructose-1,6-P2 was significantly different from the other compounds in that this metabolite was inhibitory between 1.2 and 3 mM PEP. Above this concentration, fructose-1,6-P2 activated the enzyme and abolished substrate inhibition by PEP. The enzyme was not affected by glucose, glyceraldehyde-3-P, 2-phosphoglycerate, lactate, malate, fumerate, succinate, and cyclic AMP. The results suggest that the pyruvate kinase from V. parvula M4 plays a central role in the control of gluconeogenesis in this organism by regulating the concentration of PEP.
Adenosine Monophosphate↗
Nitrite reduction in Veillonella alcalescens.
Nitrite reduction was examined in Veillonella alcalescens C-1, and obligate anaerobe with an ATP-yielding nitrate-reducing system. Hydrogen donors for nitrite reduction included hydrosulfite, hydrogen gas, and pyruvate, but not pyridine nucleotides, in the presnece or absence of flavins. Pyruvate-linked nitrite reduction was not inhibited by 4,4,4-trifluoro-1-(2-thienyl) 1,3-butanedione, dicoumarol, or 2-heptyl-4-hydroxy-quinoline-N-oxide. The noninvolvement of membrane-bound factors was supported by the fact that 100% of pyruvate-linked activity remained in the soluble fraction after fractionation of crude extracts by ultracentrifugation. Using DEAE-cellulose column chromatography, however, the participation of ferredoxin in nitrite reduction was demonstrated. The product of nitrite reduction appeared to be ammonia, as determined from H2-to-NO2- ratios. Nitrite reductase was induced by nitrate or nitrite and was repressed by increased levels of reduced nitrogenous compounds.
Anaerobiosis↗
Synthesis of alpha-ketoglutarate by reductive carboxylation of succinate in Veillonella, Selenomonas, and Bacteriodes species.
Evidence for reductive carboxylation of succinate to synthesize alpha-ketoglutarate was sought in anaerobic heterotrophs from the rumen and from other anaerobic habitats. Cultures were grown in media containing unlabeled energy substrates plus [14C]succinate, and synthesis of cellular glutamate with a much higher specific activity than that of cellular asparate was taken as evidence for alpha-ketoglutarate synthase activity. Our results indicate alpha-ketoglutarate synthase functions in Selenomonas ruminantium, Veillonella alcalescens, Bacteroides fragilis, Bacteroides vulgatus, Bacteroides uniformis, Bacteroides distasonis, and Bacteroides multiacidus. Evidence for this carboxylation was not found in strains representative of 10 other species.
Amino Acids↗
Acetate kinase from Veillonella alcalescens. Regulation of enzyme activity by succinate and substrates.
Acetate kinase of Veillonella alcalescens has been shown to be highly regulated enzyme exhibiting two levels of control: the requirement for succinate as a heterotropic allosteric effector, and cooperative binding at the substrate level. Succinate addition was necessary for enzymatic activity in both the direction of acyl phosphate synthesis and that of ATP synthesis. Control at the substrate level was apparent in the cooperative binding (Hill coefficients of 2) of acetyl phosphate, ATP, and ADP. Typical Michaelis kinetic data were observed for succinate (Ka = 20 mM for acetyl phosphate synthesis, 0.4 mM for ATP synthesis), acetate, and propionate. The primary effect of succinate was to increase the apparent Vmax of the enzymatic reaction for the variable substrates, ATP, ADP, and acetyl phosphate. The results are interpreted as evidence that, as a heterotropic effector of the acetate kinase reaction, succinate may regulate levels of propionyl-CoA (produced from propionyl phosphate by action of phosphotransacetylase), a compound required for the conversion of succinate to propionate. Acetase kinase has been shown to be a probable dimeric protein composed of two subunits of molecular weight 44,000 each.
Acetates↗
Acetate kinase from Veillonella alcalescens. Purification and physical properties.
Acetate kinase (ATP:phosphotransferase E.C.2.7.2.1) has been purified to a high state of purity from Veillonella alcalescens. The native enzyme had a molecular weight of 88,000, as determined by Sephadex G-150 gel filtration. The molecular weight of the monomeric enzyme, estimated from sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was 42,000. The enzyme was determined to be a homodimer from the amino acid composition and the results of trypsin digestion and cyanogen bromide cleavage. Two moles of phosphate were incorporated into the dimer upon incubation of the enzyme with ATP and acetate. These results support the conclusion that each subunit of the dimeric enzyme consists of a single active catalytic center. Succinate enhanced the rate of ATP-ADP phosphoryl group exchange 20-fold and the binding of ATP 10-fold. These results are considered in light of data from previous reports (Pelroy, R. A., and Whiteley, H. R. (1971) J. Bacteriol. 105, 259-267; Bowman, C. M., Valdez, R. O., and Nishimura, J. S. (1976) J. Biol. Chem 251, 3117-3121).
Acetate Kinase↗