Showing papers on "Melibiose published in 1979"

The cultural and biochemical characters of Streptococcus milleri strains isolated from human sources.

Abstract: A collection of 346 strains of Streptococcus milleri from a variety of human sources was examined culturally and biochemically, and for the presence of Lancefield group antigens. Most of the strains were non-haemolytic and ungroupable, but 25% were β haemolytic and 19% were α haemolytic; 28% possessed a group antigen (A, 5%; C, 6%, F, 14%, G, 3%). These antigens were present in 69% of β-haemolytic but in only 13% of α-haemolytic or non-haemolytic strains; β haemolysis occurred in 82% of group-F strains, 43% of other groupable strains and 11% of ungroupable strains. The following reactions were given by > 80% of S. milleri strains: hydrolysis of arginine and aesculin, a positive Voges—Proskauer reaction, and acidification of trehalose, lactose, salicin and sucrose. A minority of strains showed enhancement of growth by CO2, bile tolerance, NaCl tolerance, and ability to acidify other sugars, notably mannitol, raffinose and melibiose. Departures from the modal pattern of biochemical reactions showed a weak correlation with the type of haemolysis and the presence or absence of a group antigen but were not sufficiently systematic for clear-cut subdivisions to be recognized within the species. S. milleri therefore appeared to comprise a `central' group of non-haemolytic strains that rarely formed a Lancefield-group antigen, in which the aesculin reaction was nearly always positive, lactose was usually acidified, and a considerable minority showed enhancement of growth by CO2 and bile tolerance. Deviations from this pattern were of two main types. (1) Loss'ofo≠ormoreofthesereactions,whichtended→beassociatedwithβ−haemolysisandpresenceofagroupanti≥n.Intheserespects,α−haemolyticstra∈stended→oupyan∫ermediateposition.(2)Loss′ofo≠ormoreofthesereactions,whichtended→beassociatedwithβ-haemolysisandpresenceofagroupanti≥n.Intheserespects,α-haemolyticstra∈stended→oupyan∫ermediateposition.(2)Gain' of the ability to acidify additional sugars, notably raffinose and melibiose or mannitol; this occurred mainly among otherwise typical non-haemolytic strains that were rarely groupable. Only 12% of isolations from the bloodstream of patients suffering from systemic infections were β haemolytic and only 18% possessed a group antigen, but a considerably greater proportion of those from visceral abscesses were β haemolytic (28%). Among isolations from superficial lesions in some body sites there were considerably greater proportions of β-haemolytic and groupable strains; thus, nearly one-half of those isolated from the abdomen other than the female genital tract were β-haemolytic and over one-half were groupable. On the other hand, strains from the teeth and gums were nearly always non-haemolytic and ungroupable, and most vaginal isolations were of non-haemolytic strains with a wide sugar-fermentation pattern.

Salient features of Haemophilus vaginalis.

Abstract: A total of 78 strains of Haemophilus vaginalis were examined for 104 features. All strains fermented dextrin, maltose, and starch. Additionally, more than 90% of the strains fermented galactose, glucose, and ribose. Arbutin, cellobiose, melibiose, rhamnose, and salicin were not fermented by any of these strains. None of the strains acidified any of 14 alcohols or alkalinized any of 25 organic salts and amides. More than 90% of the strains hemolyzed human blood agar and hydrolyzed hippurate. No strain hemolyzed sheep blood agar. A recommendation is included for those minimal features that best differentiate H. vaginalis from other oxidase- and catalase-negative, gram-negative organisms.

Inhibition of adsorption of Streptococcus mutans strains to saliva-treated hydroxyapatite by galactose and certain amines.

Abstract: Adsorption of all of eight strains of Streptococcus mutans to saliva-treated hydroxyapatite (S-HA) surfaces was inhibited by galactose and melibiose, but not by other neutral sugars tested. This observation supports the hypothesis that lectin-like components participate in the attachment of these streptococci to salivary glycoproteins on saliva-treated hydroxyapatite surfaces. Adsorption of all strains was also inhibited by iodoacetate and spermine; other amines tested reduced adsorption of some strains, but not others.

Simultaneous quantitative determination of sucrose, raffinose and stachyose by invertase hydrolysis and gas—liquid chromatography

Abstract: A method for small-scale (ca 0.5 mg) quantitative determination of sucrose, raffinose and stachyose is described. After invertase hydrolysis, glucose, fructose and melibiose were estimated by gas-liquid chromatography of the trimethylsilyl derivatives. Sucrose and raffinose were directly estimated from glucose and melibiose levels, respectively. Stachyose values were calculated from the amounts of fructose remaining after deductions were made for the calculated sucrose and raffinose levels. The accuracy of the method from known saccharide mixtures was 6% for sucrose, 3% for raffinose and 10% for stachyose. The method was also shown to be able to simultaneously determine inositols and inositol galactosides.

Induction of beta-galactosidase in Streptomyces violaceus.

Abstract: Synthesis of beta-galactosidase by Streptomyces violaceus was induced by D-galactose and L-arabinose, and to a lesser extent by lactose, D-arabinose, and methyl-beta-D-galactopyranoside. The synthesis of the enzyme was linear and started to increase 2--3 h after induction by galactose, reaching a maximum after 5--7 h. The highest level of specific activity was observed in 2% galactose, with an increase of 45 times over the basal level in glycerol. Isopropyl-beta-D-thiogalactopyranoside (IPTG) and methyl-beta-D-thiogalactopyranoside (TMG) inhibited induction by D-galactose, but did not influence enzymatic activity. Cellular extracts hydrolyzed O-nitrophenyl-beta-D-galactopyranoside, but did not significantly hydrolyze lactose, melibiose, p-nitrophenyl-alpha-D-galactopyranoside, p-nitrophenyl-beta-D-fucoside, or p-nitrophenyl-beta-D-glucopyranoside. Rifampicin and chloramphenicol inhibited beta-galactosidase synthesis in non-preinduced and in preinduced cells. The inhibition by chloramphenicol was reversible.

GROWTH OF Clostridium perfringens STRAINS ON α-GALACTOSIDES

Abstract: Five strains of Clostridium perfringens type A varied greatly in their ability to utilize and grow on the α-galactosides raffinose, stachyose, and melibiose when these sugars were added (1%) to a casein-digest medium. Stachyose and raffinose were utilized rapidly by NCTC strain 8798, and at moderate rate by NCTC strains 8238 and 10240. Strain KA3 utilized raffinose at moderate rates, but stachyose not at all. Strain FD-1 utilized raffinose only to a slight extent, and stachyose not at ail. NCTC strains 8238 and 10240 sporulated heavily during growth on raffinose and stachyose. The implications of these findings on previous work linking C. perfringens to legume-induced human flatulence is discussed.

Transport of alpha-p-nitrophenylgalactoside by the lactose carrier of Escherichia coli.

Abstract: alpha-p-Nitrophenylgalactoside was found to be accumulated by the lactose transport-system of Escherichia coli. This fact may help to resolve the differences in the reported number of sugar binding sites of the lactose transport protein in nonenergized and energized membrane vesicles.

A galactosyltransferase from Erwinia amylovora and its possible role in biosynthesis of polysaccharide in infected tissues

Abstract: A galactosyltransferase (UDP galactose: D-glucose 4-β-galactosyl transferase; E.C. 2.4.l.22) was partially purified by 30 to 75% ammonium sulfate fractionation, QAE-Sephadex and Sephadex G 150 column chromatography from a soluble fraction (40 000 g) of sonicated bacterial cells of Erwinia amylovora (ATCC 19381). The enzyme activity was assayed in a 0·l ml aqueous reaction mixture containing 5 μmol of Tris-HCI buffer, pH 7·2, 4 μmol of manganese chloride, 47 pmol of UDP-(1'C) galactose (2·7 x 104 dpm), 2 μmol of acceptor and enzyme preparation. This enzyme transferred galactose from UDP-galactose to glucose in the presence of α-lactalbumin and to N-acetylglucosamine and amylovorin primer in the absence of α-lactalbumin. n -Acetylgalactosamine, maltose and melibiose were not galactose acceptors. The specificity of the enzyme suggests that the galactosyltransferase may play an important role in the production of amylovorin, a galactose-rich polysaccharide, found in the exudates on the surface of apple and pear tissues infected by E. amylovora.

Transport of Sugars in Bacteria

Abstract: Bacteria are free-living microorganisms often confronted with a large variety of environments. The occurrence in nature of different substances as main carbon source for their nutrition and the selective advantage of metabolizing fast any of these for fast proliferation promoted the development along the evolution of different adaptive uptake and catabolic equipments. The aim of the experiments presented here is to make acquaintance with two typical uptake systems in Escherichia coli, both inducible, i.e., synthesized by wild-type strains only when growing on the relevant carbon source or an inducing analog. Besides the general pattern of saturable accumulation uptake, the comparison of lactose and melibiose permeases illustrates the high degree of specificity, the possibility of overlaps in substrate specificity, and the possibility of different systems of energization, by the protonmotive force for lactose, by cotransport with sodium ion for melibiose.