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At least 271 records · Page 15Linked to original sources
PubMed2006

Paenibacillus campinasensis BL11: a wood material-utilizing bacterial strain isolated from black liquor.

In order to search for new thermophilic microorganisms and their enzymes, bacterial strains from black liquor of brownstock at washing stage of kraft pulping process were screened. Therein a multiple glycosyl hydrolase-producing strain, BL11, was isolated as a dominant species in the xylan-degrading bacterial population and identified as Paenibacillus campinasensis. The bacterial strain used all kinds of saccharides and polysaccharides, except lignin as carbon source and produced multiple extracellular polysaccharide-degrading enzymes, including one xylanase (41 kDa), three cellulases (42, 57 and 86 kDa), one pectinase (28 kDa) and one cyclodextrin glucanotransferase (38 kDa). P. campinasensis BL11 lacked lipase and protease activities and was able to grow over a wide range of pH, but it particularly grew well around neutral pH at 55 degrees C. Based on its physiological characteristics, it has strong potential for industrial application and bioresource utilization.

Bacillaceae↗
PubMed2004

Depolymerization of beta-chitin to mono- and disaccharides by the serum fraction from the para rubber tree, Hevea brasiliensis.

The serum fraction of latex from Hevea brasiliensis, the para rubber tree, is known to contain an endo-chitinolytic enzyme, hevamine. Herein the activity of the rubber serum towards beta-chitin is investigated. The serum contained 6 mg/mL of protein and a chitinolytic activity of 18 mU permg of protein. The optimum ratio of enzyme to chitin was 0.22 mU/mg, and the optimum substrate concentration was 60 mg/mL. The optimum pH range was pH2-4, and the optimum temperature was 45 degrees C. At these conditions both (GlcNAc)2 and GlcNAc were produced in a molar ratio of approximately 2:1. The hydrolysis of 300 mg of chitin with 64 mU of the rubber serum for 8 days under the optimum conditions gave 39 mg of GlcNAc and 108 mg of (GlcNAc)2 as determined by HPLC. Mixing the rubber serum preparation with an Aspergillus niger pectinase preparation containing beta-N-acetylhexosaminidase can be used to produce almost exclusively the GlcNAc monomer in about 50% yield.

Aspergillus niger↗
PubMed2006

Pectin-like acidic polysaccharide from Panax ginseng with selective antiadhesive activity against pathogenic bacteria.

Previous studies have revealed the inhibitory effects of an acidic polysaccharide purified from the root of Panax ginseng against the adhesion of Helicobacter pylori to gastric epithelial cells and the ability of Porphyromonas gingivalis to agglutinate erythrocytes. In this study, this acidic polysaccharide from P. ginseng, PG-F2, was investigated further, in order to characterize its antiadhesive effects against Actinobacillus actinomycetemcomitans, Propionibacterium acnes, and Staphylococcus aureus. The minimum inhibitory concentrations (MIC) were found to be in a range of 0.25-0.5mg/mL. However, results showed no inhibitory effects of PG-F2 against Lactobacillus acidophilus, Escherichia coli, or Staphylococcus epidermidis. PG-F2 is a pectin-type polysaccharide with a mean MW of 1.2 x 10(4) Da, and consists primarily of galacturonic and glucuronic acids along with rhamnose, arabinose, and galactose as minor components. The complete hydrolysis of PG-F2 via chemical or carbohydrolase enzyme treatment resulted in the abrogation of its antiadhesive activity, but limited hydrolysis via treatment with pectinase (EC. 3.2.1.15) yielded an oligosaccharide fraction, with activity comparable to the precursor PG-F2 (the MIC of ca. 0.01 mg/mL against H. pylori and P. gingivalis). Our results suggest that PG-F2 may exert a selective antiadhesive effect against pathogenic bacteria, while having no effects on beneficial and commensal bacteria.

Bacteria↗
PubMed2006

Safety evaluation of pigment containing Aspergillus carbonarius biomass in albino rats.

Aspergillus carbonarius, an ascomycetes fungus, is known to produce pectinase in solid-state fermentation. A mutant strain of A. carbonarius UV-10046 selected for temperature tolerance over produced polygalacturonase and during growth accumulated an yellow pigment in its biomass. Since the colored fungus suggested its application for food use, the freeze-dried biomass was evaluated to assess its safety in experimental animals. Acute and sub-acute toxicity studies were conducted on both sexes of albino rats. Feeding acute doses of A. carbonarius freeze-dried biomass at 0.5-5.0g/kg body weight to adult rats did not show any symptoms of toxicity or mortality of the rats. Similarly, dietary feeding of A. carbonarius at 0.25-2.0% level (w/w) for 14 weeks did not produce any significant changes in food intake or gain in body weight of the experimental rats compared to control rats. There were no significant differences in the relative weight of vital organs, hematological parameters, macroscopic and microscopic changes in vital organs and serum enzyme levels between the experimental and control groups. The results clearly showed that acute and sub-acute oral feeding of freeze-dried whole cells of A. carbonarius mutant for 14 weeks did not produce any toxic effects in male and female rats.

Administration, Oral↗
PubMed2004

Transcriptional regulation of plant cell wall degradation by filamentous fungi.

Plant cell wall consists mainly of the large biopolymers cellulose, hemicellulose, lignin and pectin. These biopolymers are degraded by many microorganisms, in particular filamentous fungi, with the aid of extracellular enzymes. Filamentous fungi have a key role in degradation of the most abundant biopolymers found in nature, cellulose and hemicelluloses, and therefore are essential for the maintenance of the global carbon cycle. The production of plant cell wall degrading enzymes, cellulases, hemicellulases, ligninases and pectinases, is regulated mainly at the transcriptional level in filamentous fungi. The genes are induced in the presence of the polymers or molecules derived from the polymers and repressed under growth conditions where the production of these enzymes is not necessary, such as on glucose. The expression of the genes encoding the enzymes is regulated by various environmental and cellular factors, some of which are common while others are more unique to either a certain fungus or a class of enzymes. This review summarises our current knowledge on the transcriptional regulation, focusing on the recently characterized transcription factors that regulate genes coding for enzymes involved in the breakdown of plant cell wall biopolymers.

Biodegradation, Environmental↗
PubMed2005

Pectinolytic enzymes secreted by yeasts from tropical fruits.

Three hundred yeasts isolated from tropical fruits were screened in relation to secretion of pectinases. Twenty-one isolates were able to produce polygalacturonase and among them seven isolates could secrete pectin lyase. None of the isolates was able to secrete pectin methylesterase. The pectinolytic yeasts identified belonged to six different genera. Kluyveromyces wickerhamii isolated from the fruit mangaba (Hancornia speciosa) secreted the highest amount of polygalacturonase, followed by K. marxianus and Stephanoascus smithiae. The yeast Debaryomyces hansenii produced the greatest decrease in viscosity while only 3% of the glycosidic linkages were hydrolysed, indicating that the enzyme secreted was an endo-polygalacturonase. The hydrolysis of pectin by polygalacturonase secreted by S. smithiae suggested an exo-splitting mechanism. The other yeast species studied showed low polygalacturonase activity.

Carboxylic Ester Hydrolases↗
PubMed2006

Cloning, genomic organisation and mRNA expression of a pectin lyase gene from a mutant strain of Penicillium occitanis.

The regulatory cis elements of fungal pectinases are well studied in Aspergillus genera but little is known in other fungal species. A genomic bank from Penicillium occitanis fungus is constructed and screened by previously isolated cDNA probe of a pectin lyase. From several isolated clones, the nucleotide sequence of the pectin lyase gene was completed and led to the identification of introns and promoter-terminator regions. A streaking future was found in pnl gene of P. occitanis: it exhibits the highest nucleotide homology with the pnlA of Aspergillus niger but the positions of its 4 introns is completely identical to that of A. niger pnlB gene. In addition to the determination of transcription start site, the promoter sequence from the pnl gene was analysed. It showed the conservation of known consensus sequences -CreA, Hap2-3-4, PacC ...-, and the existence of a particular sequence -CCTGA- which is similar to that already found to be specific of pectinolytic gene in Aspergillus, CCCTGA. This result suggests that the corresponding regulatory trans-acting factor should be the same as in Aspergillus.

3' Flanking Region↗
PubMed2006

An ultracentrifugation-based approach to the detection of hepatitis A virus in soft fruits.

A method was developed for detection of hepatitis A virus (HAV) in soft fruits (raspberries and strawberries). After washing the sample in 1 M sodium bicarbonate with added soya protein, fruits were removed by slow speed centrifugation, then particulate material and residual pectin were removed from the supernatant by flocculation and pectinase treatment during another slow speed centrifugation. Virus particles were then sedimented by ultracentrifugation. RNA was extracted from the virus particles, and nested RTPCR was performed on the nucleic acid extract. Nested RTPCR comprised an RTPCR, followed by PCR to amplify sequences within the amplicon. Internal amplification controls (IACs) were constructed for both the RTPCR and the PCR. The sensitivity of the nested RTPCR was approximately 10 RTPCRU. The overall method was shown to be able to detect 10(4) RTPCRU HAV in 90 g fresh strawberries, and 10(3) RTPCRU HAV in 60 g fresh raspberries. It is estimated that the lowest possible limit of detection of the method should be between 40 and 400 RTPCRU HAV per fruit sample. The method can be performed within one day, in suitably equipped microbiological laboratories, and is suitable for routine screening of food samples, and for analysis of suspected samples, e.g. during outbreak investigations.

Centrifugation↗
PubMed2005

Role of extracytoplasmic leucine rich repeat proteins in plant defence mechanisms.

Plant-pathogen interactions involve highly complex series of reactions in disease development. Plants are endowed with both, resistance and defence genes. The activation of defence genes after contact with avirulence gene products of pathogens depends on signals transduced by leucine-rich repeats (LRRs) contained in resistance genes. Additionally, LRRs play roles for various actions following ligand recognition. Polygalacturonase inhibiting proteins (PGIPs), the only plant LRR protein with known ligands, are pectinase inhibitors, bound by ionic interactions to the extracellular matrix (ECM) of plant cells. They have a high affinity for fungal endopolygalacturonases (endoPGs). PGIP genes are organised in families encoding proteins with similar physical characteristics but different specificities. They are induced by infection and stress related signals. The molecular basis of PG-PGIP interaction serves as a model to understand the evolution of plant LRR proteins in recognising non-self-molecules. Extensins form a different class of structural proteins with repetitive sequences. They are also regulated by wounding and pathogen infection. Linkage of extensins with LRR motifs is highly significant in defending host tissues against pathogen invasion. Overexpression of PGIPs or expression of several PGIPs in a plant tissue, and perhaps manipulation of extensin expression could be possible strategies for disease management.

Extracellular Matrix↗
PubMed1980

The C-5 hydrogen isotope-effect in myo-inositol 1-phosphate synthase as evidence for the myo-inositol oxidation-pathway.

The hydrogen isotope-effect that occurs in vitro during myo-inositol1-phosphate synthase-catalyzed conversion of D-[5-3H]glucose 6-phosphate into myo[2-3H]inositol 1-phosphate has been used to compare the functional role of the nucleotide sugar oxidation-pathway with that of the myo-inositol oxidation-pathway in germinating lily pollen. Results reveal a significant difference between the 3H/14C ratios of glucosyl and galactosyluronic residues from pectinase-amyloglucosidase hydrolyzates of the 70% ethanol-insoluble fraction of D-[5-3H, 1-14C]glucose-labeled, germinating lily pollen. This isotope effect at C-5 of D-glucose that occurred during its conversion into D-galactosyluronic residues of pectic substance is not explained by loss of 3H when UDP-D-[5-3H, 1-14C]glucose is oxidized by UDP-D-glucose dehydrogenase from germinating lily pollen. The evidence obtained from this study favors a functional role for the myo-inositol oxidation-pathway during in vivo conversion of glucose into galactosyluronic residues of pectin in germinating lily pollen.

Carbohydrate Epimerases↗
PubMed2001

Structural elucidation of a new arabinogalactan from the leaves of Nerium indicum.

A polysaccharide fraction, NIB-2, was obtained from the 3% aqueous sodium carbonate extract of Nerium indicum leaves using anion-exchange chromatography and gel-permeation chromatography. It was found to be composed of rhamnose, arabinose, galactose, in the ratios of 1.0:10.4:4.4, along with 4% of galacturonic acid. The results of methylation analysis, periodate oxidation, partial acid hydrolysis, pectinase treatment, and 13C and 1H NMR spectroscopy indicate that it is mainly an arabinogalactan having a backbone of 1,6-linked beta-Galp, with branches at O-3, consisting of terminal, 1,5-, and 1,3,5-linked arabinofuranosyl residues, and a small proportion of galactosyl residues at the termini. Rhamnose and galacturonic acid arose from a contaminating rhamnogalacturonan.

Galactans↗
PubMed2002

Application of mass spectrometry to determine the activity and specificity of pectin lyase A.

Electrospray ionization (ESI) with quadrupole ion-trap mass spectrometry was used to assess the activity and specificity of the enzyme pectin lyase A (PLA) (EC 4.2.2.10) on model pectins with varying degrees and patterns of methyl esterification. PLA is a pectinase which cleaves alpha-(1-->4)-glycosidic linkages in pectin by a trans-elimination process. Using pectins with different degrees and patterns of methyl esterification, there was a significant variation in the activity rate of PLA. The enzymatic products generated at various time intervals were structurally analyzed by mass spectrometry to determine the specificity of PLA. Although the preferred substrate for PLA is fully methyl esterified polygalacturonate, cleavage was also observed with a non-methyl esterified galacturonic acid residue on either the non-reducing end or the reducing end. The current study shows that although PLA prefers fully methyl esterified substrates it can also accept partially esterified ones. It also demonstrates the suitability of ESI ion-trap mass spectrometry in determining enzyme specificities.

Carbohydrate Sequence↗
PubMed2000

Salivary proteins of aphids, a pilot study on identification, separation and immunolocalisation.

Salivary proteins (SPs) of Schizaphis graminum, Acyrthosiphon pisum and Myzus persicae were studied after probing and feeding on different artificial diets. Salivary sheaths as well as apical lumps of saliva were found, presumably representing subsequently excreted saliva of different types. Phenoloxidase, pectinase and peroxidase activities were detected by staining the enzyme-converted products, thus confirming these enzyme activities found earlier by others. Proteinase and cellulase were not found. SPs in three major SDS-PAGE bands, at 154 and 66/69 kDa, were collected in fluid diets (soluble fraction) and as sheath material (solid fraction) attached to the membranes covering these diets. Proteins of both fractions presumably represented the enzymatic activities found, although this could not be proven. The lack of electrophoretic mobility of the undenaturated (isoelectrofocusing and PAGE) active proteins meant that they could not be separated, whereas the mobile denaturated (SDS-PAGE) proteins had lost their enzyme activity. Polyclonal antibodies, anti-SP154 and anti-SP66/69, both cross-reacted to most salivary proteins in Western blots. They also reacted to sheath material and to the principal salivary glands. For further studies of saliva some monoclonal antibodies were developed. The complexity of salivation and the relation of the results obtained to the behaviourally known secretion periods is discussed.

Journal Article↗
PubMed2003

Survival of Atta sexdens workers on different food sources.

Leaf-cutting ants belonging to the tribe Attini are major herbivores and important agriculture pests in the neotropics, these ants being thought to feed on the sap which exudes from the plant material which they cut and also on the mycelium of a symbiotic fungus that grows on plant material inside their nests in what is called "the fungus garden". However, we have found that the survival of Atta sexdens worker ants on leaves, on mycelium of the ants' symbiotic fungus, Leucoagaricus gongylophorus, or on plant polysaccharides was the same as that of starved A. sexdens, while, conversely, significantly longer survival was achieved by ants fed on the fungus garden material or on some of the products (especially glucose) of the hydrolysis of plant polysaccharides. We found that the fungus garden contained glucose at a higher concentration than that found in leaves or fungal mycelium, and that this glucose was consumed by the ant to the extent that it was probably responsible for up to 50% of the nutritional needs of the workers. The fungus garden contained polysaccharide degrading enzymes (pectinase, amylase, xylanase and cellulase) in proportions similar to that observed in laboratory cultures of L. gongylophorus. It thus appears that A. sexdens workers obtain a significant part of their nutrients from plant polysaccharide hydrolysis products produced by the action of extracellular enzymes released by L. gongylophorus. In this paper we discuss the symbiotic nutrition strategy of A. sexdens workers and brood and the role played by plant polysaccharides in the nutrition of attine ants.

Animals↗
PubMed1997

Effects of microgravity on the structure and function of plant cell walls.

The structural, biochemical, cytofluorimetric and electron cytochemical features of the cell walls of higher plants grown under weightlessness and simulated microgravity are described. Space flight and laboratory clinostatic experiments with plants show that the ultrastructure of the cell wall, its polysaccharide composition, and metabolic organization depend on the type of tissue and the duration of weightlessness. Horizontal clinostating that reproduced the biological effects of microgravity on cell walls showed that the structure of the external walls of the epidermis of aboveground organs is very sensitive to microgravity. Various responses occur in the primary and secondary walls under weightlessness and clinorotation: rearrangement of cell walls and organelles and changes in the content of cellulose, lignin, callose, and hemicelluloses. It is shown that plant cell wall changes under microgravity are connected with changes in cellulase, pectinase, and peroxidase activity and a change in the calcium balance in the cytoplasm and apoplast.

Calcium↗
PubMed2001

The architecture of parallel beta-helices and related folds.

Three-dimensional structures have been determined of a large number of proteins characterized by a repetitive fold where each of the repeats (coils) supplies a strand to one or more parallel beta-sheets. Some of these proteins form superfamilies of proteins, which have probably arisen by divergent evolution from a common ancestor. The classical example is the family including four families of pectinases without obviously related primary sequences, the phage P22 tailspike endorhamnosidase, chrondroitinase B and possibly pertactin from Bordetella pertusis. These show extensive stacking of similar residues to give aliphatic, aromatic and polar stacks such as the asparagine ladder. This suggests that coils can be added or removed by duplication or deletion of the DNA corresponding to one or more coils and explains how homologous proteins can have different numbers of coils. This process can also account for the evolution of other families of proteins such as the beta-rolls, the leucine-rich repeat proteins, the hexapeptide repeat family, two separate families of beta-helical antifreeze proteins and the spiral folds. These families need not be related to each other but will share features such as relative untwisted beta-sheets, stacking of similar residues and turns between beta-strands of approximately 90 degrees often stabilized by hydrogen bonding along the direction of the parallel beta-helix.Repetitive folds present special problems in the comparison of structures but offer attractive targets for structure prediction. The stacking of similar residues on a flat parallel beta-sheet may account for the formation of amyloid with beta-strands at right-angles to the fibril axis from many unrelated peptides.

Amino Acid Sequence↗
PubMed2001

Combined effect of operational variables and enzyme activity on aqueous enzymatic extraction of oil and protein from soybean.

The individual effect of two different enzymes-protease and cellulase-on oil and protein extraction yields combined with other process parameters-enzyme concentration, time of hydrolysis, particle size and solid-to-liquid ratio-was evaluated by Response Surface Methodology. The selection of the enzymes for the study was based on preliminary experiments that showed higher increments in the extraction yield with the use of the two enzymes when compared to hemicellulase and pectinase. The levels of the quantitative parameters studied were: i) enzyme concentration: 0.1, 0.45, 2 w/w %; ii) liquid-to-solid ratio: 0.05, 0.125, 0.2; iii) mean particle size: 212.5, 449.5, 855 µm; iv) time of hydrolysis: 30; 60; 120 min. Experimental data for both oil and protein extraction yields obtained with and without enzymes correlated very well with process parameters (P < 0.0001), resulting in models with high coefficient of determination for oil and protein extraction yields (r(2) = 0.9570 and r(2) = 0.9807, respectively). The use of protease resulted in significantly higher yields over the control (protein yield increased from 27.8 to 66.2%, oil yield increased from 41.8 to 58.7%) only when heat treated flour was used, or when non-heat treated flour with large particle sizes was used in the extraction. The yields of protein and oil from non-heat treated material in general decreased slightly with the use of enzymes.

Journal Article↗
PubMed2001

Enzymatic isolation and structural characterisation of polymeric suberin of cork from Quercus suber L.

An enzymatic method has been used to isolate, for the first time, polymeric suberin from the bark of Quercus suber L. or cork. This was achieved by solvent extraction (dichloromethane, ethanol and water), followed by a step-by-step enzymatic treatment with cellulase, hemicellulase and pectinase, and a final extraction with dioxane/water. The progress of suberin isolation was monitored by Fourier transform infrared spectroscopy using a photoacoustic cell (FTIR-PAS). The material obtained (polymeric suberin (PS)) was characterised by solid-state and liquid-state nuclear magnetic resonance, FTIR-PAS and vapour pressure osmometry, and compared with the suberin fraction obtained by alkaline depolymerisation (depolymerised suberin (DS)). The results showed that PS is an aliphatic polyester of saturated and unsaturated fatty acids, with an average molecular weight (M(w)) of 2050 g mol(-1). Although this fraction represents only 10% of the whole suberin of cork, its polymeric nature gives valuable information about the native form of the polymer. DS was found to have an average M(w) of 750 g mol(-1) and to comprise a significant amount of acidic and alcoholic short aliphatic chains.

Bacterial Proteins↗