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PubMed1985

Evidence that the mechanisms of fungitoxicity of 8-quinolinol and its bischelate with copper(II) are different.

The copper(II) contents of the growth media, Sabouraud dextrose and Czapek-Dox broths, and of the spore inocula of Aspergillus niger (ATCC 1004), Aspergillus oryzae (ATCC 1011), Trichoderma viride (ATCC 8678), and Myrothecium verrucaria (ATCC 9095) were determined by atomic absorption spectrophotometry in a graphite furnace. The test systems composed of Sabouraud dextrose broth and spore inocula of the four fungi contained only a little over 3% of the copper(II) required to form a minimal inhibitory concentration of bis(8-quinolinolato)copper(II). The test system of Czapek-Dox broth and A. oryzae contained slightly less than 65% of the copper(II) required to form a minimal inhibitory concentration of the bischelate of 8-quinolinol with copper(II). When the minimal inhibitory concentrations of 8-quinolinol and bis(8-quinolinolato)copper(II) were added simultaneously to the test system of Czapek-Dox broth and A. oryzae, 10% of the combined mixture of toxicants caused complete inhibition of growth indicating synergism between the toxicants. These results together with the observation that alpha-lipoic acid as well as small aliphatic thiol-containing compounds (cysteine, glutathione, dithioerythritol, and dithiothreitol) reversed the toxicity of 8-quinolinol but not the toxicity of bis(8-quinolinolato)copper(II) led to the conclusion that the mechanisms of fungitoxicity of both toxicants are different.

Aspergillus↗

PubMed2000

Inactivation of phytotoxin produced by the rice sheath blight pathogen Rhizoctonia solani.

The rice sheath blight pathogen, Rhizoctonia solani, produces a toxin designated as RS-toxin, a carbohydrate compound containing mainly alpha-glucose and mannose. Different microflora were tested for RS-toxin inactivation. Isolates of Trichoderma viride inactivated this toxin when it was provided as the sole food source, and these isolates reduced the severity of toxin-induced symptoms and electrolyte leakage from rice cells. The best-performing isolate, TvMNT7, produced two extracellular proteins of 110 and 17 kDa. The high molecular mass protein was shown to have alpha-glucosidase activity. The purified 110 kDa protein was able to reduce RS-toxin activity.

Blotting, Western↗

PubMed2004

Development of selective media for the isolation and enumeration of Alternaria species from soil and plant debris.

A new semi-selective medium, acidified weak potato-dextrose agar (AWPDA) with Mertect (active ingredient: thiabendazole), was developed for the isolation and enumeration of Alternaria species from samples of soil and plant debris. The medium was selected based on growth inhibition tests against Alternaria and several other commonly encountered saprobic fungi utilizing three antifungal agents, Botran (active ingredient: dichloran), Bayleton (active ingredient: triadimefon), and Mertect, and two basal media, acidified potato-dextrose agar (APDA) and AWPDA. Botran inhibited growth of Rhizopus stolonifer moderately, but had little effect on Cladosporium cladosporoides, Fusarium oxysporum, Penicillium chrysogenum, or Trichoderma harzianum. Bayleton inhibited growth of R. stolonifer and C. cladosporoides severely, and inhibited growth of F. oxysporum, P. chrysogenum, and T. harzianum moderately. Mertect inhibited growth of C. cladosporoides, F. oxysporum, P. chrysogenum, and T. harzianum completely, but had little or moderate effect on R. stolonifer. All three antifungal agents inhibited growth of Alternaria species slightly or moderately. The combination of Bayleton and Mertect inhibited growth of all fungi severely. A comparison of recovery rates of Alternaria from soil and plant debris samples on AWPDA with Mertect and weak potato-dextrose agar (WPDA) revealed that Alternaria spp. accounted for 63.6%-81.0% of recovered fungal isolates on AWPDA with Mertect as compared to 0.6%-2.7% of recovered isolates on WPDA. The AWPDA medium with Mertect exhibited superior selective growth of Alternaria species from samples of soil and plant debris, and will be useful in studies where the recovery and enumeration of Alternaria species is necessary.

Alternaria↗

PubMed2005

A novel vitamin C analog, 2-O-(beta-D-Glucopyranosyl)ascorbic acid: examination of enzymatic synthesis and biological activity.

2-O-(beta-D-Glucopyranosyl)ascorbic acid (AA 2 beta G) isolated from a popular traditional Chinese food (Lycium fruit) was synthesized using cellulase derived from Trichoderma sp. with cellobiose as a glucose donor. 6-O-(beta-D-Glucopyranosyl)ascorbic acid as well as AA 2 beta G was also synthesized in this reaction. The vitamin C activity of AA 2 beta G was also evaluated using inherently scorbutic (osteogenic disorder Shionogi [ODS]) rats. The rats were fed vitamin C-deficient food and water containing AA 2 beta G for 21. AA 2 beta G supported their growth and the level of vitamin C in tissues was moderately maintained. The vitamin C level in some tissues depended on the hydrolytic activity of AA 2 beta G (beta-glucosidase activity) although the correlation was not statistically significant (P=0.08). The results indicate that AA 2 beta G has pro-vitamin C activity.

Administration, Oral↗

PubMed2006

Enzymatic synthesis of L-pipecolic acid by Delta1-piperideine-2-carboxylate reductase from Pseudomonas putida.

L-Pipecolic acid is a chiral pharmaceutical intermediate. An enzymatic system for the synthesis of L-pipecolic acid from L-lysine by commercial L-lysine alpha-oxidase from Trichoderma viride and an extract of recombinant Escherichia coli cells coexpressing Delta1-piperideine-2-carboxylate reductase from Pseudomonas putida and glucose dehydrogenase from Bacillus subtilis is described. A laboratory-scale process provided 27 g/l of L-pipecolic acid in 99.7% e.e.

Bacillus subtilis↗

PubMed2000

A simple and rapid method for the preparation of a cell-free extract with CCAAT-binding activity from filamentous fungi.

A simple and rapid method for the preparation of a cell-free extract with the CCAAT-binding activity was established with Aspergillus nidulans as a model fungus. Proteins were extracted with 6 M guanidine hydrochloride directly from mycelia and renatured by dialysis. This method was found applicable to other filamentous fungi such as Aspergillus oryzae and Trichoderma viride.

Aspergillus↗

PubMed2001

Enzymatic synthesis of two ginsenoside Re-beta-xylosides.

Two new beta-xylosyl derivatives of ginsenoside Re, 20(S)-protopanaxatriol 6-O-alpha-L-rhamnopyranosyl-(1 --> 2)-[beta-D-xylopyranosyl-(1 --> 4)]-beta-D-glucopyranosyl-20-O-beta-D-glucopyranoside and 20(S)-protopanaxatriol 6-O-alpha-L-rhamnopyranosyl-(1 --> 2)-[beta-D-xylopyranosyl-(1 --> 6)]-beta-D-glucopyranosyl-20-O-beta-D-glucopyranoside, were respectively synthesized from p-nitrophenyl beta-D-xylopyranoside and phenyl beta-D-xylopyranoside as donors and ginsenoside Re as the acceptor in 25% acetone and acetonitrile by a cellulase preparation from Trichoderma viride and a beta-galactosidase preparation from Aspergillus oryzae. The latter enzyme preparation also catalyzed the hydrolysis of ginsenoside Re to the minor saponin, ginsenoside Rg2.

Aspergillus oryzae↗

PubMed2001

Molecular cloning and characterization of cel2 from the fungus Cochlibolus carbonum.

A new cellulase gene, cel2, from the filamentous fungus Cochliobolus carbonum was cloned by using egl-1 of Trichoderma reesei as a heterologous probe. DNA blot analysis of cel2 showed that this gene is present as a single copy. The gene contains one 49-bp- intron. cel2 encodes a predicted protein (Cel2p) of 423 amino acids with a molecular mass of 45.8 kDa. The predicted pI is 4.96. It shows similarity to other endoglucanases from various fungi. From the comparison with other cellulase genes, cel2 belongs to family 7 of glucohydrolases. cel2 is located on a 2.5-Mb chromosome in C. carbonum and its expression is repressed by sucrose. A cel2 mutant of C. carbonum was created by transformation-mediated gene disruption. The pathogenicity of the mutant was indistinguishable from the wild type, indicating that cel2 by itself is not important for pathogenicity.

Amino Acid Sequence↗

PubMed2002

Determination of the stereochemistry of (-)-koninginin A by an X-ray analysis of its synthetic sample.

The absolute configuration of (-)-koninginin A [10-hexyl-11, 12-dioxatricyclo[7.2. 1.0<1 ,6>]dodecane-2,5-diol (1)], the antibiotic metabolite of Trichoderma koningii and T. harzianum, was determined as 1S, 2R, 5S, 6S, 9S, 10S by an X-ray crystallographic analysis of its synthetic sample coupled with the established stereochemical outcome of Sharpless asymmetric dihydroxylation used as the key reaction to prepare intermediate 4.

Benzoxepins↗

PubMed2002

Antifungal activity of rye (Secale cereale) seed chitinases: the different binding manner of class I and class II chitinases to the fungal cell walls.

The antifungal activities of rye seed chitinase-a (RSC-a, class I) and -c (RSC-c, class II) were studied in detail using two different bioassays with Trichoderma sp. as well as binding and degradation experiments with the cell walls prepared from its mycelia. RSC-a inhibited more strongly the re-extension of the hyphae, containing mainly mature cells, than RSC-c did. Upon incubation of the fungus with fluorescent chitinases, FITC-labeled RSC-a was found to be located in the hyphal tips, lateral walls, and septa, while FITC-labeled RSC-c was only in the hyphal tip. RSC-a had a greater affinity for the cell walls than RSC-c. RSC-a liberated a larger amount of reducing sugar from the cell walls than RSC-c did. These results inferred that RSC-a first binds to the lateral walls and septa, consisting of the mature cell walls, and degrades mature chitin fiber, while RSC-c binds only to the hyphal tip followed by degradation of only nascent chitin. As a result, RSC-a inhibited fungal growth more effectively than RSC-c. Furthermore, it was suggested that the chitin-binding domain in RSC-a assists the antifungal action of RSC-a by binding to the fungal hypha.

Antifungal Agents↗

PubMed2003

Synthesis of glyceroyl beta-N-acetyllactosaminide and its derivatives through a condensation reaction by cellulase.

A condensation reaction between N-acetyllactosamine and glycerol was directly catalyzed by using a commercially available cellulase preparation from Trichoderma reesei. 1-O-beta-N-Acetyllactosaminyl-(R, S)-glycerols (1) were readily synthesized in a 5% yield based on the N-acetyllactosamine added and conveniently isolated by two-step column chromatographies. The use of a partially purified enzyme increased 2.3-fold the yield of 1, compared to that of the crude enzyme containing beta-D-galactosidase activity. When various alkanols (n:2-4) were used in the condensation reaction, the corresponding alkyl beta-N-acetyllactosaminides were obtained in yields of 0.3-1.1% of the desired compounds.

Cellulase↗

PubMed2003

Family 19 chitinase of Streptomyces griseus HUT6037 increases plant resistance to the fungal disease.

Chitinase C (ChiC) is the first bacterial family 19 chitinase discovered in Streptomyces griseus HUT6037. In vitro, ChiC clearly inhibited hyphal extension of Trichoderma reesei but a rice family 19 chitinase did not. In order to investigate the effects of ChiC as an increaser of plant resistance to fungal diseases, the chiC gene was introduced into rice plants under the control of the increased CaMV 35S promoter and a signal sequence from the rice chitinase gene. Transgenic plants were morphologically normal. Resistance to leaf blast disease caused by Magnaporthe grisea was evaluated in R1 and R2 generations using a spray method. Ninety percent of transgenic rice plants expressing ChiC had higher resistance than non-transgenic plants. Disease resistance of sibling plants within the same line was correlated with the ChiC expression levels. ChiC produced in rice plants accumulated intercellularly and had the hydrolyzing activity against glycol chitin.

Antifungal Agents↗

PubMed2004

Purification and antifungal activity of recombinant chitinase from Escherichia coli carrying the family 19 chitinase gene of Streptomyces sp. J-13-3.

A recombinant chitinase was purified from the cell extract of Escherichia coli JM109 transformed by plasmid pUC19 carrying the gene encoding family 19 chitinase of Streptomyces sp. J-13-3 by column chromatography on DEAE-Sepharose, CM-Sepharose, and Bio-Gel P-100. The final preparation was homogenous in polyacrylamide gel electrophoresis. The molecular weight of the purified enzyme was estimated to be 32,000. The recombinant chitinase hydrolyzed the trimer to hexamer of N-acetylglucosamine and had the identical N-terminal amino acid sequence of the mature protein, indicating removal of the signal sequence by E. coli signal peptidase. The fungal growth in well (200 microl of medium) of microplate by measurement of absorbance at 595 nm indicated that the chitinase (10 microg) completely and half inhibited growth of Trichoderma reesei and Aspergillus niger respectively.

Acetylglucosamine↗

PubMed2004

Molecular cloning, functional expression, and mutagenesis of cDNA encoding class I chitinase from rye (Secale cereale) seeds.

A cDNA encoding rye seed chitinase-a (RSC-a) was cloned by rapid amplification of cDNA ends and PCR procedures. It consists of 1,191 nucleotides and encodes an open reading frame of 321 amino acid residues. Recombinant RSC-a (rRSC-a) was produced in the oxidative cytoplasm of Escherichia coli Origami(DE3) in a soluble form by inducing bacteria at a low temperature (20 degrees C). Purified rRSC-a showed properties similar to the original enzyme from rye seeds in terms of chitinase activity toward a soluble substrate, glycolchitin, and an insoluble substrate, chitin beads, in chitin-binding ability to chitin, and in antifungal activity against Trichoderma sp. in vitro. rRSC-a mutants were subsequently produced and purified by the same procedures as those for rRSC-a. Mutation of Trp23 to Ala decreased the chitinase activity toward both substrates and impaired the chitin-binding ability. Furthermore, the antifungal activity of this mutant was weakened with increasing of the NaCl concentration in the culture medium. Complete abolishment of both activities was observed upon the mutation of Glu126 to Gln. The roles of these residues in both activities are discussed.

Amino Acid Sequence↗

PubMed2005

Purification, characterization, and antifungal activity of chitinases from pineapple (Ananas comosus) leaf.

Three chitinases, designated pineapple leaf chitinase (PL Chi)-A, -B, and -C were purified from the leaves of pineapple (Ananas comosus) using chitin affinity column chromatography followed by several column chromatographies. PL Chi-A is a class III chitinase having a molecular mass of 25 kDa and an isoelectric point of 4.4. PL Chi-B and -C are class I chitinases having molecular masses of 33 kDa and 39 kDa and isoelectric points of 7.9 and 4.6 respectively. PL Chi-C is a glycoprotein and the others are simple proteins. The optimum pHs of PL Chi-A, -B, and -C toward glycolchitin are pH 3, 4, and 9 respectively. The chitin-binding ability of PL Chi-C is higher than that of PL Chi-B, and PL Chi-A has lower chitin-binding ability than the others. At low ionic strength, PL Chi-B exhibits strong antifungal activity toward Trichoderma viride but the others do not. At high ionic strength, PL Chi-B and -C exhibit strong and weak antifungal activity respectively. PL Chi-A does not have antifungal activity.

Amino Acid Sequence↗

PubMed2001

Biological control of Fusarium moniliforme in maize.

Fusarium moniliforme Sheldon, a biological species of the mating populations within the (italic)Gibberella fujikuroi species complex, i.e., population A [= G. moniliformis (Sheld.) Wineland], is an example of a facultative fungal endophyte. During the biotrophic endophytic association with maize, as well as during saprophytic growth, F. moniliforme produces the fumonisins. The fungus is transmitted vertically and horizontally to the next generation of plants via clonal infection of seeds and plant debris. Horizontal infection is the manner by which this fungus is spread contagiously and through which infection occurs from the outside that can be reduced by application of certain fungicides. The endophytic phase is vertically transmitted. This type infection is important because it is not controlled by seed applications of fungicides, and it remains the reservoir from which infection and toxin biosynthesis takes place in each generation of plants. Thus, vertical transmission of this fungus is just as important as horizontal transmission. A biological control system using an endophytic bacterium, Bacillus subtilis, has been developed that shows great promise for reducing mycotoxin accumulation during the endophytic (vertical transmission) growth phase. Because this bacterium occupies the identical ecological niche within the plant, it is considered an ecological homologue to F. moniliforme, and the inhibitory mechanism, regardless of the mode of action, operates on the competitive exclusion principle. In addition to this bacterium, an isolate of a species of the fungus Trichoderma shows promise in the postharvest control of the growth and toxin accumulation from F. moniliforme on corn in storage.

Antibiosis↗

PubMed2002

Possibilities for recycling cellulases after use in cotton processing: part II: Separation of cellulases from reaction products and released dyestuffs by ultrafiltration.

The adsorption and activity of a total cellulase (Trichoderma reesei) was measured and compared on undyed and dyed cotton fabrics. Recovery of enzymes from the reaction mixture and by desorption from the cotton substrate was evaluated. About 80% of the initial protein could be recovered. The removal of released products (soluble reducing sugars and dyes) from the treatment liquor and subsequent concentration of cellulase proteins was performed using an ultrafiltration membrane. Strong protein-dye interactions made it impossible to separate efficiently the dyes from the enzyme-containing treatment liquors. The use of surfactants did not enhance cellulase desorption from cotton fabric. Although anionic surfactants have a deactivating effect on cellulases, this effect seems to be reversible, since after ultrafiltration the cellulase activity was similar to that of enzymes desorbed with buffer only. Humicola insolens cellulases were shown to be much more sensitive to anionic surfactant than T. reesei cellulases. The use of cellulases that bind reversibly to cellulose is suggested for achieving more efficient cellulase recycling and for reducing backstaining by dye-cellulase complexes.

Adsorption↗

PubMed2004

Discrimination among eight modified michaelis-menten kinetics models of cellulose hydrolysis with a large range of substrate/enzyme ratios: inhibition by cellobiose.

The kinetics of exoglucanase (Cel7A) from Trichoderma reesei was investigated in the presence of cellobiose and 24 different enzyme/Avicel ratios for 47 h, in order to establish which of the eight available kinetic models best explained the factors involved. The heterogeneous catalysis was studied and the kinetic parameters were estimated employing integrated forms of Michaelis-Menten equations through the use of nonlinear least squares. It was found that cellulose hydrolysis follows a model that takes into account competitive inhibition by cellobiose (final product) with the following parameters: Km = 3.8 mM, Kic = 0.041 mM, kcat = 2 h-1 (5.6 x 10-4 s-1). Other models, such as mixed type inhibition and those incorporating improvements concerning inhibition by substrate and parabolic inhibition, increased the modulation performance very slightly. The results support the hypothesis that nonproductive enzyme substrate complexes, parabolic inhibition, and enzyme inactivation (Selwyn test) are not the principal constraints in enzymatic cellulose hydrolysis. Under our conditions, the increment in hydrolysis was not significant for substrate/enzyme ratios <6.5.

Algorithms↗