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Journal ArticleDOI

The effect of certain cultural factors on production of dextransucrase by Leuconostoc mesenteroides.

01 Oct 1952-Journal of Bacteriology (American Society for Microbiology (ASM))-Vol. 64, Iss: 4, pp 521-526
TL;DR: Observation on factors affecting production of dextransucrase from Leuconostoc mesenteroides, strain NRRL B-512 and the possibility that more than one enzyme may be involved in the synthesis ofdextran is recognized.
Abstract: Present knowledge on the characteristics of dextransucrase and its mode of action is based primarily on the important investigations of Hehre (1941, 1946, 1951) and Hehre and Sugg (1942). Hitherto, a serious impediment to studies of this interesting enzyme has been the difficulty of procuring dextransucrase. Development of further knowledge about it would be greatly facilitated by the availability of culture liquors rich in dextransucrase. The rapid formation of dextransucrase in high yields has been reported in a preliminary note (Koepsell and Tsuchiya, 1952). The present report deals in greater detail with our observations on factors affecting production of dextransucrase from Leuconostoc mesenteroides, strain NRRL B-512.2 However, culture liquors high in activity have been obtained from a large number of the organisms tested. The dextran produced by strain NRRL B-512 in the conventional whole culture procedure contains about 95 per cent a-1,6-glucopyranosidic linkage. Although the non-1,6 linkages have been assumed to be of the a-1,4 type, definite proof on this point is lacking (Jeanes and Wilham, 1950). L. mesenteroides, strain NRRL B-512, or its substrains, is the organism principally used in investigations of clinical dextran in the United States. Although the term \"dextransucrase\" is used in the singular for convenience, the possibility that more than one enzyme may be involved in the synthesis of dextran is recognized.
Citations
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Book ChapterDOI
TL;DR: In this paper, a review summarises recent results on structure characterisation of dextran including some comments on biosynthesis of this important class of biopolymers, and highlights recent progress in esterification of both inorganic and organic polysaccharide esters, etherification reactions towards ionic and non-ionic ethers, and the huge variety of different conversions mainly developed for the binding of drugs.
Abstract: Dextran, comprising a family of neutral polysaccharides consisting of an α-(1 → 6) linked d-glucose main chain with varying proportions of linkages and branches, depending on the bacteria used, is an interesting starting material for chemical modification reactions for the design of new functional polymers with promising properties. The review summarises recent results on structure characterisation of dextran including some comments on biosynthesis of this important class of biopolymers. Applications of dextran are discussed as well. Chemical modification reactions of dextran are increasingly studied for the structure and hence property design. The review highlights recent progress in esterification of dextran, both inorganic and organic polysaccharide esters, etherification reactions towards ionic and non-ionic ethers, and the huge variety of different conversions mainly developed for the binding of drugs. It summarises recent developments in the application of dextran derivatives with a focus on the chemical structures behind these materials such as prodrugs, bioactivity of inorganic dextran esters, heparin sulfate mimics, hydrogels, nanoparticles and self assembly structures for surface modification.

278 citations

Journal ArticleDOI
TL;DR: A new fermentation process has been developed to produce an innovative functional ingredient for bakery industry using a specific LAB strain able to produce a sufficient amount of HMW dextran assuring a significant impact on bread volume.

143 citations


Cites background from "The effect of certain cultural fact..."

  • ...Temperature, sucrose concentration and enzyme concentration have also been reported as affecting the molecular weight of dextran (Tsuchiya et al., 1952)....

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  • ...During fermentation, the pH drops naturally through the organic acid production of the strain, passing all pH levels of enzyme induction, bioconversion and fermentation of residual fructose (Lazic et al., 1993; Tsuchiya et al., 1952)....

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Journal ArticleDOI
TL;DR: Experiments strongly suggest that the binding sites for free GTase are the surface glucans, and cell-associated and extracellular GTases are most likely alternate states of the same enzyme protein.
Abstract: Streptococcus mutans strain B13 (serotype D) almost exclusively produced free glucosyltransferase (GTase) in the culture supernatant when grown in sucrose-free TTY broth medium, which was composed of Trypticase (Baltimore Biological Laboratory [BBL] Cockeysville, Md.), tryptose (Difco Laboratories, Detroit, Mich.), yeast extract (BBL), salts, and 1% glucose. Organisms grown in sucrose-free TTY broth retained very weak cell-associated GTase activity and did not adhere significantly to glass surfaces in the presence of exogenous sucrose. If sucrose was added to TTY broth, however, GTase was found on the cell surface where cell-bound, water-insoluble glucans were synthesized. Most commercially available products of Todd-Hewitt broth were found to contain trace amounts of sucrose, as did Trypticase soy broth (BBL), whereas brain heart infusion broth (Difco and BBL) was found to be essentially free of sucrose. Almost all detectable GTase activity was cell associated when S. mutans B13 was grown in Todd-Hewitt or trypticase soy broth. Heat-treated B13 cells grown in Todd-Hewitt broth and cell-free, water-insoluble glucans bound free GTase and produced marked adherence in the presence of sucrose. Experiments strongly suggest that the binding sites for free GTase are the surface glucans, and cell-associated and extracellular GTases are most likely alternate states of the same enzyme protein.

140 citations

Journal ArticleDOI
TL;DR: The production of dextransucrase from Leuconostoc mesenteroides NRRL B-512F was stimulated 2-fold by the addition of 0.005% of calcium chloride to the medium; levansucrase levels were unaffected; and the mannoglycoprotein character of the enzyme was confirmed.

121 citations

References
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Journal ArticleDOI
Michael Somogyi1

2,447 citations

Journal ArticleDOI
TL;DR: A study of acceptor specificity in dextran synthesis was undertaken with the object of elucidating the polymerization mechanism and it was hoped that clues leading to the direct enzymatic synthesis of “clinical” dextransucrase with an average molecular weight in the range of 50,000 to 100,000 would be found.
Abstract: CurTent events have intensified interest in blood plasma substitutes. Partially hydrolyzed dextran is under study in many laboratories for this purpose. The parent substance, \"native\" dextran, is a glucose polymer in which a-1 ,6-glucopyranosidic linkages predominate, and is produced by growing Leuconostoc mesenteroides or other suitable bacteria on media containing sucrose. Hehre (Science: 93, 237, 1941), Stacey (Nature: 149, 639, 1942), and others have obtained it by use of cell-free preparations of dextransucrase, the dextran-synthesizing enzyme, elaborated by these organisms. Partial hydrolysis of native dextran is necessary to reduce the molecular size from several millions to approximately 75,000 as desired for its use as a plasma substitute. Preliminary experiments with cell-free dextransucrase preparations have suggested that the molecular size of the dextran produced can be varied by modifying reaction conditions, and dextran of proper size for clinical use might be obtainable by direct synthesis. Large scale use of an enzymatic process for the production of dextran requires simple and economical production of highly potent enzyme preparations. This note will describe certain cultural factors which have recently been found to lead to rapid formation of dextransucrase in high yield in a medium suitable for industrial production of the enzyme. Although this report deals only with enzyme preparations from L. mesenteroides, strain NRRL B-512, active enzyme preparations have been obtained from many strains of L. mesenteroides and other organisms. The high sucrose levels commonly used in the production of dextran lead to viscous cultures from which separation of bacterial cells is difficult. We have found that low sugar concentrations obviate this difficulty without seriously curtailing high yields of dextransucrase. A cell-free enzyme preparation is obtained simply by centrifuging or filtering the cultures. The nitrogen and other nutrient requirements of the organism can be satisfied by corn steep liquor and mineral salts. Dextransucrase potency of the enzyme preparations is assayed by measuring the amount of fructose produced, as determined by the copper-reduction method of Somogyi (J. Biol. Chem., 160, 61, 1945), in a given time under ideal reaction conditions. The assay reaction mixture contains 10 per cent sucrose, M/20 acetate as buffer at pH 5.0, and the enzyme, and is held at 30 C. Enzyme potency is proportional to fructose production, providing that less than one-half of the sucrose has been utilized. One dextransucrase unit is defined as the amount of enzyme which will convert one mg of sucrose in one hour under these conditions. A cultural factor critically affecting enzyme yields is close control of pH of

110 citations