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C Bucke

Publications and source records attributed to C Bucke.

At least 19 recordsLinked to original sources
PubMed2006

Polyhydroxyalkanoate (PHA) biosynthesis from structurally unrelated carbon sources by a newly characterized Bacillus spp.

A newly acquired polyhydroxyalkanoate (PHA) producing Bacillus spp. was identified to be a strain of Bacillus cereus using a range of microbiological and molecular techniques. This strain, named B. cereus SPV, was found to be capable of using a wide range of carbon sources including glucose, fructose, sucrose, various fatty acids and gluconate for the production of PHAs, an advantage for the commercial production of the polymers. The media used for the polymer production was novel in the context of the genus Bacillus. The PHA, once produced, was found to remain at a constant maximal concentration, without any degradation, a great advantage for the commercial production of the PHAs. This particular strain of Bacillus spp. was able to synthesize various PHAs with 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV) and 4-hydroxybutyrate (4HB)-like monomer units from structurally unrelated carbon sources such as fructose, sucrose and gluconate. This is the first report of the incorporation of a 4HB related monomer containing PHA by the genus Bacillus and from structurally unrelated carbon sources. The PHAs isolated had molecular weights ranging between (0.4 and 0.8) x 10(6) and low polydispersity index values (M(W)/M(N)) ranging from 2.6 to 3.4.

Bacillus cereus↗
PubMed2004

Elicitor effects on reactive oxygen species in liquid cultures of Penicillium chrysogenum.

Activity of reactive oxygen species (ROS) was investigated in liquid cultures of Penicillium chrysogenum P2 supplemented with carbohydrates. Oligosaccharides lowered the ROS activity in all samples. The greatest effect occurred when oligosaccharides were added to samples 48 h after inoculation. The ROS decrease in the presence of oligoguluronate, oligomannuronate and mannan oligosaccharides was 18%, 36% and 54%, respectively (ROS levels varied notably with culture age and type of elicitor). The polysaccharides from which the oligosaccharides were derived showed little (5-10%) overall decrease of ROS.

Bioreactors↗
PubMed2001

Transformation of 2,4,6-trichlorophenol by free and immobilized fungal laccase.

Laccase from the white rot fungus Coriolus versicolor was immobilized on Celite R-637 by covalent binding with glutaraldehyde. After a sharp primary decline in activity (up to 50%), the retained enzyme activity was stable over a storage period of 33 days at 4 degrees C. A comparative study of soluble and immobilized laccases revealed the increased resistance of immobilized enzyme to the unfavourable effects of alkaline pH, high temperature and the action of inhibitors. A combination of these properties of immobilized laccase resulted in the ability to oxidize 2,4,6-trichlorophenol (2,4,6-TCP) at 50 degrees C at pH 7.0. The reactions of soluble and immobilized laccase with 2,4,6-TCP were examined in the presence and absence of redox mediators. 3,5-Dichlorocatechol, 2,6-dichloro-1,4-benzoquinone and 2,6-dichloro-1,4-hydroquinone were found to be the primary products of 2,4,6-TCP oxidation by laccase; oligo- and polymeric compounds were also found.

Basidiomycota↗
PubMed2001

Using 2', 7'-dichlorodihydrofluorescein-diacetate to assess polysaccharides as immunomodulating agents.

Neutrophils play a key role in the defense against microbial infections. One of their primary weapons to destroy microbes is the production of reactive oxygen species (ROS). This paper shows how 2', 7'-dichlorodihydrofluorescein-diacetate (DCFH-DA) was used to measure the effects of polysaccharides on the production of ROS by polymorphonuclear leukocytes (PMNs). The DCFH-DA method has been designed to provide a highly sensitive, quantifiable, real-time assessment of ROS production by PMNs.

Adjuvants, Immunologic↗
PubMed2000

Addition of polar organic solvents can improve the product selectivity of cyclodextrin glycosyltransferase. Solvent effects on cgtase.

Cyclodextrin glycosyltransferase (EC 2.4.1.19, CGTase) is an enzyme that produces cyclodextrins from starch via an intramolecular transglycosylation reaction. Addition of small amounts (10% v/v) of polar organic solvents can affect both the overall production yield and the type of cyclodextrin produced from a maltodextrin substrate under simulated industrial process conditions. Using CGTase from Thermoanaerobacter sp. all solvents produced an increase in cyclodextrin yield when compared with a control, the greatest increase being obtained with addition of ethanol (26%). In addition product selectivity was affected by the nature of the organic solvent used: beta-cyclodextrin was favoured in the absence of any solvent and on the addition of dimethylsulphoxide, t-butanol and dimethylformanide while alpha-cyclodextrin was favoured by addition of acetonitrile, ethanol and tetrahydrofuran. With CGTase from Bacillus circulans strain 251 relatively smaller increases in overall cyclodextrin production were achieved (between 5-10%). Addition of t-butanol to a B. circulans catalysed reaction however did produce the largest selectivity for beta-cyclodextrin of any solvent-enzyme combination (82%). The effect of solvent addition was shown not to be related to the product inhibition of CGTase, but may be related to reduced competition from the intermolecular transglycosylation reaction that causes degradation of cyclodextrin products. This rate of this reaction was shown to be dependent on the nature of the organic solvent used.

Journal Article↗
PubMed2000

The immobilization of microbial cells, subcellular organelles, and enzymes in calcium alginate gels. Reprinted from Biotechnology and Bioengineering, Vol. XIX, No. 3, Pages 387-397 (1977).

Saccharomyces cerevisiae cells, Kluyveromyces marxianus cells, inulase, glucose oxidase, chloroplasts, and mitochondria were immobilized in calcium alginate gels. Ethanol production from glucose solutions by an immobilized preparation of S. cerevisiae was demonstrated over a total of twenty-three days, and the half-life of such a preparation was shown to be about ten days. Immobilized K. marxianus, inulase, and glucose oxidase preparations were used to demonstrate the porosity and retraining properties of calcium alginate gels. Calcium alginate-immobilized chloroplasts were shown to perform the Hill reaction. Some experiments with immobilized mitochondria are reported.

Alginates↗
PubMed1998

Enhanced penicillin production by oligosaccharides from batch cultures of Penicillium chrysogenum in stirred-tank reactors.

Alginate and galactomannan-derived oligosaccharides enhanced the production of penicillin G when added to stirred tank reactor cultures of Penicillium chrysogenum. The addition of oligomannuronate and oligoguluronate blocks increased penicillin G yield by 47% and 49%, respectively. The effect of mannan oligosaccharides was found to be more pronounced with 69% higher yield than the control cultures. The maximum increase in the average specific productivity of the oligosaccharide augmented cultures was 55% after addition of mannan oligosaccharides. In addition, a difference was observed in all cases in the accumulation pattern of the intermediate of penicillin biosynthesis, delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine.

Alginates↗
PubMed1998

Separation, characterization, and specificity of alpha-mannosidases from Vigna umbellata.

Information about the specificity of glycosidase enzymes is important since it affects their use for characterization and synthesis of oligosaccharides. Two alpha-mannosidases (EC 3.2.1.24), I and II, were isolated from rice beans (Vigna umbellata). The native molecular weight of both isozymes was estimated to be 329,000, but pIs of form I were 5.03-5.34 and pIs of form II were 5.46-6.20. The two isozymes were characterized in terms of optimal pH and temperature, effects of metal ions, inhibition by swainsonine and 1-deoxymannojirimycin, and kinetic parameters for p-nitrophenyl-alpha-D-mannopyranoside and Man alpha (1-2)Man. Both enzymes were more specific towards Man alpha (1-2)Man in both hydrolysis and synthesis, but their hydrolytic specificities towards Man alpha (1-3)[Man alpha (1-6)]Man were different.

Chromatography, High Pressure Liquid↗
PubMed1994

Use of INT to determine the respiratory activity of immobilised and free Penicillium chrysogenum.

The specific oxygen uptake rates (OUR) of kappa-carrageenan-immobilised and free cell cultures of Penicillium chrysogenum were determined using an oxygen electrode in a closed chamber. This was compared with the respiratory activity determined by the extent of staining with iodo-nitrophenyl tetrazolium chloride (INT). The degree of INT staining correlated with the OUR; an increase in INT deposition corresponding to an increase in the measured OUR. The INT staining technique could therefore be used to determine cell respiratory activity. In this way a profile of fungal cell activity throughout immobilised cell aggregates and free cell pellets was determined. In both types of cell culture, after the initial growth period only the peripheral biomass was observed to be active.

Fermentation↗
PubMed1993

Physiological studies related to the immobilization of Penicillium chrysogenum and penicillin production.

Using the production of penicillin by Penicillium chrysogenum as a model system, certain physiological aspects of immobilized and free cell cultures were compared. Reducing the immobilized viable spore loading (from 4 x 10(4) to 2 x 10(3) spores ml-1 gel) and initial bead diameter (from 3.5-4.0 to 1.5-2.0 mm) gave rise to an increase in the penicillin titer from 0.2 to 1.2 g l-1. Using these conditions in immobilized cell culture the growth phase was prolonged and the duration of expression of the isopenicillin N synthase gene (pcbC) was significantly extended when compared with free cell culture (150 h as opposed to 100 h). During the period of maximum penicillin production, different penicillin biosynthetic intermediates accumulated in the broth of free and immobilized cell cultures, reflecting a fundamental difference in cell physiology. Although the maximum specific productivity of penicillin production was reduced by immobilization, the average specific productivity increased when compared to free cell fermentation.

Biotechnology↗
PubMed1993

Primary sequence analysis and representation techniques in carbohydrates.

Sequence similarity calculations of carbohydrates present several problems which must be addressed if a computer implementation is to be achieved. These problems range from the computational representation of the complex carbohydrate structure to the method by which the comparison of residue and linkage is to be made. This paper therefore discusses the form of this representation and how two or more carbohydrates can be meaningful compared. An example set of results using this approach is presented and discussed to illustrate how similarity comparison can show relationships between carbohydrates, features that are otherwise hidden by the sheer volume of data which must be considered.

Algorithms↗
PubMed1992

The application of aqueous two-phase systems to oligosaccharide synthesis by alpha-mannosidase catalysed glycosyl transfer reactions.

Aqueous two-phase systems formed from PEG and dextran have been applied to the synthesis of oligosaccharide by Jack bean alpha-mannosidase in reverse. Whilst rates of synthesis and percentage yields were similar in two-phase systems and one-phase aqueous buffer systems, a ten-fold increase in yield of product per unit of enzyme was seen. In addition, the use of aqueous two-phase systems offers potential process advantages over one-phase systems for the synthesis of oligosaccharides.

Carbohydrate Sequence↗
PubMed1991

The effects of spore loading on the growth of Penicillium chrysogenum immobilised in kappa-carrageenan.

Penicillium chrysogenum spores were immobilised in kappa-carrageenan. The effect of the number of viable spores immobilised per bead on the rate of germination and degree of subsequent mycelial growth was investigated. The distribution of active mycelium throughout the bead was determined. At a high spore loading (10(3)-10(4) viable spores per bead) the biomass concentration was low and the majority of the actively respiring biomass was located at the bead periphery. Reducing the spore loading (to 50 viable spores per bead) resulted in a fourfold increase in immobilised biomass concentration. At very low spore loadings (5 and 10 viable spores per bead) the concentration of biomass decreased, but mass transfer throughout the bead improved and the uniformity of active immobilised biomass increased. The spore loading also affected the morphology of the growing hyphae and the extent of free cell growth.

Carrageenan↗
PubMed1989

A high-performance liquid chromatography method for the simultaneous assay of diaminopimelate epimerase and decarboxylase.

A sensitive and comparatively simple method for the assay of diaminopimelate (DAP) decarboxylase, which simultaneously monitors DAP epimerase activity, in the reverse of the biosynthetic direction, is described. The substrate, meso-DAP and products LL-DAP and L-lysine are derivatized with o-phthaldialdehyde and resolved by reversed-phase high-performance liquid chromatography. Separation is achieved on a Spherisorb C18 column using a gradient elution system. This technique offers a high degree of sensitivity as the detection method described can measure picomole quantities of substrate and products.

Amino Acid Isomerases↗