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R Marchant

Publications and source records attributed to R Marchant.

At least 19 recordsLinked to original sources
PubMed2006

Characterization of a fungal strain isolated from a polyphenol polluted site.

A group of fungal strains were isolated from a polyphenol polluted soil, taken from an olive oil processing plant in Attica, Greece. The fungi were tested for their ability to decolorize a polyaromatic dye Poly R-478, which was used as a model compound to test their ligninolytic activities. The strain K1.1 decolorized efficiently the dye on agar plates and was further studied. PCR amplification of the internal transcribed spacer (ITS) region of the ribosomal RNA genes from the genomic DNA isolated from mycelium grown in liquid culture resulted in amplified fragments. Via BLASTN search, the length of a 773 base pairs was identified as the basidiomycetes Coprinellus xanthothrix. The growth rates and the tolerance of the fungus were compared on solid media, containing four different concentrations of pentachlorophenol. Extracellular enzyme activities (lignin peroxidase, manganese peroxidase and laccase) were determined in defined liquid medium. The isolate expressed laccase and manganese peroxidase but not lignin peroxidase. The removal of the dye was also estimated in liquid medium. The fungus showed biosorption and biotransformation as removal mechanisms.

Adsorption↗
PubMed2006

Use of Saccharomyces cerevisiae cells immobilized on orange peel as biocatalyst for alcoholic fermentation.

A biocatalyst was prepared by immobilizing a commercial Saccharomyces cerevisiae strain (baker's yeast) on orange peel pieces for use in alcoholic fermentation and for fermented food applications. Cell immobilization was shown by electron microscopy and by the efficiency of the immobilized biocatalyst for alcoholic fermentation of various carbohydrate substrates (glucose, molasses, raisin extracts) and at various temperatures (30-15 degrees C). Fermentation times in all cases were low (5-15 h) and ethanol productivities were high (av. 150.6 g/ld) showing good operational stability of the biocatalyst and suitability for commercial applications. Reasonable amounts of volatile by-products were produced at all the temperatures studied, revealing potential application of the proposed biocatalyst in fermented food applications, to improve productivities and quality.

Alcohols↗
PubMed2005

Biodegradation of lindane by Pleurotus ostreatus via central composite design.

The degradation of lindane was studied in liquid-agitated cultures using a commercial strain of the fungus Pleurotus ostreatus as the biodegrading organism. The biodegradation was accomplished with the action of extracellular oxidative enzymes, produced by the fungus to decompose woody substrates. Enzyme activities of manganese peroxidase and laccase were measured in a liquid mineral medium. An orthogonal Central Composite Design of experiments was used to construct second-order response surfaces with the fungus growth, final pH and the lindane biodegradation as optimization parameters. The initial lindane concentration, the nitrogen content, the incubation time and the temperature were used as design factors. Optimal conditions found for all these parameters will be used for the continuation of this project aiming at the bioremediation of contaminated sites with persistent organic pollutants such as lindane.

Biodegradation, Environmental↗
PubMed2004

Distribution and molecular investigation of highly thermophilic bacteria associated with cool soil environments.

In this study, both molecular and culture-based methods were used to characterize thermophilic bacteria associated with the subsurface soil environment in Northern Ireland. A total of 53 thermophilic, aerobic, sporulating and non-sporulating bacteria were isolated from subsurface soil samples obtained from two sites. They were screened by amplified ribosomal DNA restriction analysis prior to 16 S rRNA gene sequencing. The majority of the sequences were associated with Geobacillus thermoleovorans (50%) and Geobacillus caldoxylosilyticus (34.6%). Isolates F10, F20 and Tf exhibited only 93% similarity with Geobacillus toebii strain F70. Hence they may represent a new species of the genus Geobacillus.

Bacillus↗
PubMed2004

Habitat, applications and genomics of the aerobic, thermophilic genus Geobacillus.

Thermophilic bacteria belonging to Bacillus genetic group 5 have been reclassified as being members of Geobacillus gen. nov., with G. stearothermophilus as the type strain. Geobacillus species, literally meaning earth or soil Bacillus, are widely distributed and readily isolated from natural and man-made thermophilic biotopes. Work within our group has however shown that an abundance of genetically distinct Geobacillus isolates can be obtained from temperate Irish soils. As with many thermophiles there is considerable interest in potential industrial application of these bacteria and their gene products. This review describes two novel applications for Geobacillus isolates, firstly in the metabolism of the herbicide glyphosate and secondly in the metabolism of quorum-sensing signal molecules from Gram-negative bacteria. Finally the current state of the art is described for Bacillus genomics, with details given of three independent genome-sequencing projects of Geobacillus isolates.

Bacillus↗
PubMed2004

High-temperature wine making using the thermotolerant yeast strain Kluyveromyces marxianus IMB3.

Kluyveromyces marxianus IMB3 yeast cells were immobilized on delignified cellulosic material, apple, and quince separately. Both immobilized and free cells were used in high-temperature wine making, and their fermented grape must contained 3 to 4% alcohol. Semisweet wines were produced by the addition of potable alcohol to the fermented must. Preliminary sensory evaluation of the produced semisweet wines showed good flavor and aroma. The final product contained extremely low levels of higher and amyl alcohols while ethyl acetate was at levels usually present in wines. The ferment produced may be blended with other products to improve their quality.

Bioreactors↗
PubMed2003

Grape and apple wines volatile fermentation products and possible relation to spoilage.

The main volatile by-products of the alcoholic fermentation of grape wine, cider and apple pulp wine were investigated to determine if any correlated with spoilage resistance in the latter two. Spoilage was visually detected after seven days in low-alcohol grape wine in comparison to 11 and 16 days in cider and apple pulp wine, respectively. Acetaldehyde, ethyl acetate, methanol, propanol, isobutanol and amyl alcohols were the main fermentation by-products detected in all three wines. There were highest concentrations of acetaldehyde, ethyl acetate, methanol and propanol in grape wine and, therefore, these by-products could not be implicated in spoilage resistance in apple wines. Increased concentrations of isobutanol and amyl alcohols, however, in cider and apple pulp wine in comparison to grape wine might have been the reason for spoilage resistance in the apple wines.

1-Propanol↗
PubMed2003

Enhanced bioremediation of n-alkane in petroleum sludge using bacterial consortium amended with rhamnolipid and micronutrients.

The purpose of the present study was to investigate possible methods to enhance the rate of biodegradation of oil sludge from crude oil tank bottom, thus reducing the time usually required for bioremediation. Enhancement of biodegradation was achieved through bioaugmentation and biostimulation. About 10% and 20% sludge contaminated sterile and non-sterile soil samples were treated with bacterial consortium (BC), rhamnolipid biosurfactant (RL) and nitrogen, phosphorus and potassium (NPK) solution. Maximum n-alkane degradation occurred in the 10% sludge contaminated soil samples. The effects of treatment carried out with the non-sterile soil samples were more pronounced than in the sterile soils. Maximum degradation was achieved after the 56th day of treatment. n-Alkanes in the range of nC8-nC11 were degraded completely followed by nC12-nC21, nC22-nC31 and nC32-nC40 with percentage degradations of 100%, 83-98%, 80-85% and 57-73% respectively. Statistical analysis using analysis of variance and Duncan's multiple range test revealed that the level of amendments, incubation time and combination of amendments significantly influenced bacterial growth, protein concentration and surface tension at a 1% probability level. All tested additives BC, NPK and RL had significant positive effects on the bioremediation of n-alkane in petroleum sludge.

Alkanes↗
PubMed2002

Continuous whey fermentation using kefir yeast immobilized on delignified cellulosic material.

Delignified cellulosic-supported biocatalyst, prepared by immobilization of kefir yeast on delignified cellulosic material (DCM), was found to be suitable for continuous, modified whey fermentation. The modified whey contained 1% raisin extract and molasses. Ethanol productivities ranged from 3.6 to 8.3 g L(-1)day(-1), whereas parameters such as ethanol concentration, residual sugars, and daily fermented whey productivity were acceptable for the production of potable alcohol and alcoholic drinks in industrial fermentations. The continuous fermentation bioreactor was operated for 39 days, stored for 18 days at 4 degrees C, and operated again for another 15 days without any diminution of the ethanol productivity. The concentrations of higher alcohols (propanol-1, isobutyl alcohol, and amyl alcohols) were low. The main volatile byproducts formed in the continuous process were similar to those observed in alcoholic beverages, and the fermented whey had a good aroma. The concentrations of higher alcohols were very low when compared to that of ethyl acetate, therefore resulting in a quality product. The possibility of using such a process for the production of potable alcohol or a novel, low-alcohol content drink is proposed.

Animals↗
PubMed2002

High-temperature alcoholic fermentation of whey using Kluyveromyces marxianus IMB3 yeast immobilized on delignified cellulosic material.

A novel system for high-temperature alcoholic fermentation of whey is described. This system consists of Kluyveromyces marxianus yeast immobilized on delignified cellulosic material (DCM). The effect of pH, initial lactose concentration and temperature on the fermentation of a synthetic medium containing lactose was studied. Batch fermentations of whey were also carried out and the formation of volatile by-products was examined. The concentrations of higher alcohols were found to be in very low levels leading to a product of improved quality. The fermented whey had an improved characteristic aroma compared to unfermented whey. The possibility to use fermented whey as raw material for the production of a novel, low alcohol content drink was also investigated.

Alcohols↗
PubMed2002

Resolution of (RS)-proglumide using lipase from Candida cylindraceae.

Proglumide is used in the treatment of neuropathic pain. It acts by inhibiting peptide cholecystokinin (CCK). Neural injury produces an elevation in plasma CCK. Proglumide has been also shown to augment the analgesic effect of sustained release morphine in neuropathic pain. Currently proglumide is administered as a racemic mixture. In the present study, an attempt is made to separate the racemic mixture of the drug using lipase obtained from Candida cylindracea by stereoselective esterification. Enzymatic stereoselective esterification was carried out in organic solvents. The resolution was studied using a chromatographic column with a chiral support and mass spectrometry. The reaction conditions for stereoselective esterification including amount of substrate, amount of enzyme, alcohol, solvent and temperature were optimised during the present investigation. Butanol and hexanol were found to be suitable for formation of S and R esters, respectively. Hexane was the best solvent for esterification and the optimum temperature was found to be 30 degreesC.

Analgesics↗
PubMed2001

Chromatographic method for diaminopimelic acid detection in calcareous rocks. Presence of a bacterial biomarker in stromatolites.

The presence in the environment of diaminopimelic acid (DAP), a specific eubacterial marker, can be attributed to that of bacteria. We report a reliable and highly sensitive method for the quantification of DAP in calcareous rocks. It consists of acid hydrolysis of rock powder, purification of DAP by chromatography on Dowex 50W and Spherogel AA-NA+ columns, and quantitative analysis by high-performance liquid chromatography. Addition of tritiated DAP, the internal standard, allows one to follow the relevant fractions throughout the purification procedure and to determine their yield. The analytical step consists in pre-column derivatization with ortho-phthaldialdehyde of purified samples, and separation through a reversed-phase C18 column. Chemical controls, i.e., oxidation of samples to rule out the presence of co-eluting lanthionine and cystathionine, as well as mass spectrometry, confirm the presence of DAP in analyzed samples. Our method allows the separation of meso- from L- and/or D-stereoisomers of DAP, and reveals their presence in the examined rocks, two stromatolites of different age and geographic origin.

Biomarkers↗
PubMed2001

Microbial decolourisation and degradation of textile dyes.

Dyes and dyestuffs find use in a wide range of industries but are of primary importance to textile manufacturing. Wastewater from the textile industry can contain a variety of polluting substances including dyes. Increasingly, environmental legislation is being imposed to control the release of dyes, in particular azo-based compounds, into the environment. The ability of microorganisms to decolourise and metabolise dyes has long been known, and the use of bioremediation based technologies for treating textile wastewater has attracted interest. Within this review, we investigate the mechanisms by which diverse categories of microorganisms, such as the white-rot fungi and anaerobic bacterial consortia, bring about the degradation of dyestuffs.

Aerobiosis↗
PubMed2001

Remediation of dyes in textile effluent: a critical review on current treatment technologies with a proposed alternative.

The control of water pollution has become of increasing importance in recent years. The release of dyes into the environment constitutes only a small proportion of water pollution, but dyes are visible in small quantities due to their brilliance. Tightening government legislation is forcing textile industries to treat their waste effluent to an increasingly high standard. Currently, removal of dyes from effluents is by physio-chemical means. Such methods are often very costly and although the dyes are removed, accumulation of concentrated sludge creates a disposal problem. There is a need to find alternative treatments that are effective in removing dyes from large volumes of effluents and are low in cost, such as biological or combination systems. This article reviews the current available technologies and suggests an effective, cheaper alternative for dye removal and decolourisation applicable on large scale.

Adsorption↗
PubMed2001

Improving the quality of industrially important enzymes by directed evolution.

Directed evolution is a new process for developing industrially viable biocatalysts. This technique does not require a comprehensive knowledge of the relationships between sequence structure and function of proteins as required by protein engineering. It mimics the process of Darwinian evolution in a test tube combining random mutagenesis and recombination with screening or selection for enzyme variants that have the desired properties. Directed evolution helps in enhancing the enzyme performance both in natural and synthetic environments. This article reviews the process of directed evolution and its application to improve substrate specificity, activity, enantioselectivity and thermal stability.

Animals↗
PubMed2001

Racemic resolution of RS-baclofen using lipase from Candida cylindracea.

Baclofen is chemically (RS)-beta-(aminomethyl)-4-chlorobenzene propanoic acid. It is used in therapy of pain and as a muscle relaxant. Baclofen produces analgesia by increasing the concentration of gamma amino butyric acid (GABA), the major rapid inhibitory transmitter. Both the isomers of baclofen have different therapeutic activity with respect to their interaction to the receptors at the site of action. Lipase from Candida cylindracea has been used as a catalyst for resolving racemic mixtures of numerous drug molecules. The present investigation deals with the racemic resolution of RS-baclofen using lipase from Candida cylindracea and a study of the factors affecting resolution.

Baclofen↗
PubMed2000

Decolourisation of synthetic textile dyes by Phlebia tremellosa.

Phlebia tremellosa decolourised eight synthetic textile dyes (200 mg l(-1)) by greater than 96% within 14 days under stationary incubation conditions. High performance liquid chromatography analysis of culture supernatants indicated that Remazol Black B was degraded by the fungus, however, complete mineralisation did not occur as a colourless organic breakdown product accumulated. Laccase activity was detectable in culture supernatants after 5 days when the fungus was grown in the presence of an artificial textile effluent, with activity reaching a maximum of 15 U l(-1) on day 14.

Animals↗