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PubMedDate not supplied

[Effect of cyclic adenosine-3',5'-monophosphate, chloramphenicol and actinomycin D on Gluconobacter oxydans biosynthesis of extracellular levansaccharase].

The biosynthesis of levansucrase by Gluconobacter oxydans was shown to be induced in media containing sorbitol or fructose. An addition of glucose at a concentration of 0.1% to the culture growing in a medium with sorbitol stimulated the biosynthesis of levansucrase, whereas glucose at a concentration of 0.5-0.6% inhibited the enzyme synthesis by 20-30%. Gluconic acid, a product of glucose metabolism, also repressed the synthesis of levansucrase, but to a lesser degree than glucose. Cyclic adenosine-3',5-'monophosphate eliminated the repression by glucose added to a medium with sorbitol. An addition of chloramphenicol to the culture growing in a medium with sorbitol showed that the induction of levansucrase required de novo protein synthesis. The inhibiting action of chloramphenicol increased with its concentration. An increase in the concentration of actinomycin D from 5 to 200 micrograms/ml inhibited the bacterial growth by 50%, but stimulated the biosynthesis of levansucrase by 40%.

Chloramphenicol↗
PubMedDate not supplied

[Study of the pathways regulating the biosynthesis of Gluconobacter oxydans levansucrase].

The synthesis of levansucrase is derepressed during the growth of Gluconobacter oxydans L-1 in media with mannitol, sorbitol or fructose. The level of levansucrase activity under these conditions is 20-30 times higher than in cultures growing in the presence of xylite, galactose or glucose. Addition of mannitol or sucrose to the culture grown in a medium with xylite increases the differential rate of levansucrase synthesis. Addition of glucose at a concentration of 1% to the culture growing in a medium with mannitol at constant pH represses the synthesis of levansucrase only for a short period of time (15-20 min). The mechanism regulating the activity of levansucrase in the bacterial culture is susceptible to changes in the pH of the medium: the differential rate of levansucrase synthesis is three-fold higher when the culture is grown at pH 5.7 cf. pH 4.7.

Carbohydrates↗
PubMedDate not supplied

[Role of the nutrient medium components in regulating levansaccharase synthesis in Gluconobacter oxydans].

The effect of phosphate and acetate buffer systems on the growth of Gluconobacter oxydans and its synthesis of levansucrase was studied in nutrient media containing sorbitol. The intensification of constructive processes in media with an increased content of phosphate did not accelerate the enzyme biosynthesis by G. oxydans. As was shown in experiments with the intact cells of G. oxydans, the respiratory activity of the bacterium was stimulated in phosphate buffer supplemented with fructose. In contrast, acetate inhibited fructose oxidation and hindered the growth. At the same time, the synthesis of levansucrase increased. Such an increase was also found when the growth of G. oxydans was suppressed by sodium fluoride, an inhibitor of cellular metabolism. The extra synthesis of levansucrase useless during the growth on sorbitol should be attributed apparently to non-balanced growth of the bacterial culture caused by the suppression of respiration processes.

Acetates↗
PubMedDate not supplied

[Raffinose metabolism in Gluconobacter oxydans].

Metabolism of raffinose has been examined in experiments with the growing culture and washed cells of Gluconobacter oxydans L-1. Degradtion of the trisaccharide was found to be catalyzed by levansucrase, levan being synthesized, and melibiose and small quantitites of fructose being liberated in the reaction. Melibiose is not hydrolyzed and is not used by the bacterium as a source of carbon, but is oxidized to melibionic acid. Fructose is assimilated by the bacterium in constructive metabolism, being oxidized to gluconic, 2-ketogluconic acids and 5-ketofructose.

Acetobacter↗
PubMed1998

Molecular characterization of Gluconobacter oxydans recA gene and its inhibitory effect on the function of the host wild-type recA gene.

A DNA fragment containing the recA gene of Gluconobacter oxydans was isolated and further characterized for its nucleotide sequence and ability to functionally complement various recA mutations. When expressed in an Escherichia coli recA host, the G. oxydans recA protein could efficiently function in homologous recombination and DNA damage repair. The recA gene's nucleotide sequence analysis revealed a protein of 344 amino acids with a molecular mass of 38 kDa. We observed an E. coli-like LexA repressor-binding site in the G. oxydans recA gene promoter region, suggesting that a LexA-like mediated response system may exist in G. oxydans. The expression of G. oxydans recA in E. coli RR1, a recA+ strain, surprisingly caused a remarkable reduction of the host wild-type recA gene function, whereas the expression of both Serratia marcescens recA and Pseudomonas aeruginosa recA gene caused only a slight inhibitory effect on function of the host wild-type recA gene product. Compared with the E. coli RecA protein, the identity of the amino acid sequence of G. oxydans RecA protein is much lower than those RecA proteins of both S. marcescens and Pseudomonas aeruginosa. This result suggests that the expression of another wild-type RecA could interfere with host wild-type recA gene's function, and the extent of such an interference is possibly correlated to the identity of the amino acid sequence between the two classes of RecA protein.

Amino Acid Sequence↗
PubMedDate not supplied

[Physiologo-biochemical characteristics if Gluconobacter oxydans and prospects for its use in biotechnology and biosensor systems (review)].

Gluconobacter oxydans possesses a unique organization of metabolic systems, which are characterized by reduction of major dissimilation pathways, surface localization of main oxidative enzymes responsible for partial oxidation of carbon substrates, high performance of electron-transport chains, and accumulation of partially oxidized metabolites in the medium. These features allow us to use the cells of these microorganisms in biotechnology for production of several food products and medicines. The use of G. oxydans in biosensors for estimation of concentrations of sugars, aldoses and polyalcohols is promising. Physiological and biochemical features of these microorganisms enabling their use in biotechnology and receptor elements of biosensors are reviewed.

Acetobacteraceae↗
PubMed1976

An ornithine-containing lipid isolated from Gluconobacter cerinus.

The three ornithine-containing lipids of Gluconobacter cerinus were isolated from each other. One of the three lipids was postulated as Nalpha-3-hydroxypalmitoylornithine, to the fatty acid moiety of which 2-hydroxy fatty acid is linked by an ester linkage. The 2-hydroxy acid was possibly cis-11, 12-methylene-2-hydroxyoctadecanoate. Such an ornithine-containing lipid was found to be distributed in other acetic acid bacteria.

Hydroxy Acids↗
PubMed1999

A study of dextran production from maltodextrin by cell suspensions of Gluconobacter oxydans NCIB 4943.

This study investigated dextran synthesis from a commercial maltodextrin substrate using cell suspensions of G. oxydans NCIB 4943 as catalysts. Experiments were arranged according to a central composite statistical design. The effects of substrate concentration (10-100 g l-1), cell concentration (0.32-32.0 g wet weight l-1), time of reaction (8-48 h) and pH (3.5-5.5), each at three levels, on dextran yield and dextran molecular weight (MW), were investigated. Response surface methodology was used to assess factor interactions, and empirical models describing the two responses were fitted. Most of the variance in dextran yield could be explained by the fitted model (R2 = 0.96). Dextran yield ranged from 1.21 to 41.69%. The presence of significant negative quadratic effects of cell concentration and time indicated that dextran yield reached a plateau and thus, optimum levels of cell concentration and time could be identified to maximize dextran yield. Dextran MW ranged from 6.6 to 38 kDa and was characterized by the significant interactions of reaction time with substrate concentration and cell concentration. The model, however, could account for only 60% of the variance in dextran MW. Possible reasons for this are discussed.

Culture Media↗
PubMed1999

Crystallization and preliminary diffraction studies of two quinoprotein alcohol dehydrogenases (ADHs): a soluble monomeric ADH from Pseudomonas putida HK5 (ADH-IIB) and a heterotrimeric membrane-bound ADH from Gluconobacter suboxydans (ADH-GS).

Crystals of a soluble monomeric quinocytochrome alcohol dehydrogenase (ADH-IIB) and of a trimeric membrane-associated quinocytochrome alcohol dehydrogenase (ADH-GS) have been obtained. The ADH-IIB crystals are triclinic, with one monomer in the unit cell, and were obtained in the presence of PEG 8000, sodium citrate, HEPES buffer and 2-propanol. X-ray data were collected at 110 K to 1. 9 A resolution (R(merge) = 6.4%) and the orientation of a methanol dehydrogenase search molecule (from Methylophilus methylotrophus W3A1) was obtained by molecular replacement. Preliminary refinement of this model (10.0-3.0 A resolution, R = 0.37, R(free) = 0.40) led to tentative identification of the two highest peaks in a native anomalous difference Fourier map as the Fe atom of the heme and a calcium ion interacting with the PQQ prosthetic group. The ADH-GS crystals are tetragonal, displaying six similar lattices, both primitive and centered, and were grown by the sitting-drop method after replacement of Triton X-100 by dodecylmaltoside or octaethylene glycol monododecyl ether in the presence of ammonium sulfate and sodium acetate buffer, with and without PEG 3500 and calcium ion. The best diffraction is obtained at 110 K where the resolution extends to about 4 A in the a and b directions and about 3 A in the c direction.

Alcohol Oxidoreductases↗