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Showing papers on "Trichoderma harzianum published in 2002"


Journal ArticleDOI
TL;DR: These forms cause the green mold epidemic in commercially grown Agaricus bisporus in North America and Europe, respectively and are effectively indistinguishable morphologically although they have subtly different growth rates at 25 C on SNA and statistically significant micromorphological differences.
Abstract: Trichoderma aggressivum sp. nov. and T. aggressivum f. europaeum f. nov. are described. These forms cause the green mold epidemic in commercially grown Agaricus bisporus in North America and Europe, respectively. In the literature they have been reported as T. harzianum biotypes Th 4 and Th 2, respectively. They are strongly separated from their closest relative, T. harzianum, in sequences of the ITS-1 region of nuclear rDNA and an approximately 689 bp fragment of the protein coding translation elongation factor gene (EF-1α). They are distinguished from the morphologically similar T. harzianum and T. atroviride (the latter also known as biotype Th 3) most readily by rate of growth. Of these, only T. harzianum grows well and sporulates at 35 C, while T. atroviride is the slowest growing. Trichoderma aggressivum f. aggressivum and f. europaeum are effectively indistinguishable morphologically although they have subtly different growth rates at 25 C on SNA and statistically significant micromorphological differences. Based on findings of this study, descriptions of T. harzianum and T. atroviride are expanded. A key to Trichoderma species commonly found associated with commercially grown A. bisporus is provided.

369 citations


Journal ArticleDOI
TL;DR: An overview is presented of the data currently available on lytic enzymes from the mycoparasitic fungus Trichoderma and effort is being aimed at improving biocontrol agents and plants by introducing Trichodma genes via genetic manipulations.
Abstract: The use of specific mycolytic soil microorganisms to control plant pathogens is an ecological approach to overcome the problems caused by standard chemical methods of plant protection The ability to produce lytic enzymes is a widely distributed property of rhizosphere-competent fungi and bacteria Due to the higher activity of Trichoderma spp lytic enzymes as compared to the same class of enzymes from other microorganisms and plants, effort is being aimed at improving biocontrol agents and plants by introducing Trichoderma genes via genetic manipulations An overview is presented of the data currently available on lytic enzymes from the mycoparasitic fungus Trichoderma

223 citations


Journal ArticleDOI
TL;DR: Application of B. subtilis with Rhizobium is a promising approach for the improvement of bean root rot control.

120 citations


Journal ArticleDOI
TL;DR: The ability of these isolates to affect the infection of wheat seedlings by F. graminearum may be of potential value in field trials.
Abstract: Fusarium graminearum is associated with the cereal damping-off complex which reduces germination, seedling stand and yield. Fifty-two bacterial strains and six Trichoderma spp. isolated from the wheat rhizosphere were evaluated for biocontrol of seedling blight of wheat caused by F. graminearum. Their potential as biocontrol agents was tested in vitro and in the greenhouse. Isolates varied in their ability to inhibit the mycelial growth of F. graminearum in agar plate bioassays by 0–79%. This parameter was not related with biocontrol efficacy of in vivo assays. In greenhouse trials, all isolates were initially evaluated for reducing disease on wheat cultivars Klein Centauro (moderately resistant to F. graminearum) and Pro INTA Oasis (susceptible) planted in sterilized soil artificially infested with the pathogen. Among the 25 bacteria and six fungal isolates that exhibited a pronounced suppressive effect, the most efficient 10 for both cultivars were further assayed on eight cultivars (Buck Candil, Buck Catriel, Buck Chambergo, Buck Poncho, Buck Topacio, Klein Cacique, Klein Centauro and Pro INTA Oasis) potted in cultivated–inoculated soil. Three weeks after sowing, plant stand, percentage of diseased emerging seedlings, plant height and dry weight were evaluated. Among the antagonists only Stenotrophomonas maltophilia was significantly better than the control for the average of the eight cultivars for plant stand, height and dry weight. Stenotrophomonas maltophilia also caused a non-significant decrease in the percentage of diseased plants. Three strains of Bacillus cereus and one isolate of Trichoderma harzianum gave also a good control in some cultivars. The ability of these isolates to affect the infection of wheat seedlings by F. graminearum may be of potential value in field trials.

119 citations


Journal ArticleDOI
TL;DR: CHIT36 recombinant protein from the yeast Pichia pastoris was active against different phytopathogens, confirming the importance of this endochitinase in the mycoparasitic activity of Trichoderma antagonistic strains.
Abstract: The presence of the endochitinase CHIT36 from Trichoderma harzianum TM was assessed in several antagonistic Trichoderma strains belonging to different molecular taxonomic groups. CHIT37 from T. harzianum CECT 2413 was sequenced and found to display 89% homology with CHIT36 at the amino acid level. Northern analysis showed that chit36Y from T. asperellum is regulated both by glucose and nitrogen levels. Stress conditions, colloidal chitin and N-acetyl-glucosamine are effective inducers of this gene. The promoter of chit36Y was cloned and was used to direct expression of a gfp reporter gene in Trichoderma transformants. Confrontation experiments with the plant pathogen Rhizoctonia solani revealed that direct contact between the fungi is not necessary for gfp expression. The R. solani-inducing factor appears to be a soluble molecule capable of diffusing through a dialysis membrane (<12 kDa). CHIT36 recombinant protein from the yeast Pichia pastoris was active against different phytopathogens, confirming the importance of this endochitinase in the mycoparasitic activity of Trichoderma antagonistic strains.

118 citations


Journal ArticleDOI
TL;DR: The dual culture of Trichoderma harzianum and Catharanthus roseus callus produced an antimicrobial compound with a remarkable activity against the Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis and a homolog of the fungal metabolite equisetin.
Abstract: The dual culture of Trichoderma harzianum and Catharanthus roseus callus produced an antimicrobial compound with a remarkable activity against the Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis. Structural elucidation revealed that this compound, which we have named trichosetin, is a novel tetramic acid (2,4-pyrrolidinedione) antibiotic and a homolog of the fungal metabolite equisetin. This compound however, was not produced in the individual culture of T. harzianum or C. roseus callus.

102 citations


Journal ArticleDOI
TL;DR: Indigenous fungi isolated from soil of a former gasworks site were investigated in submerged cultures with pyrene as the sole carbon source for the first time, and may be ideal candidates for effective bioremediation of polycyclic aromatic hydrocarbons.
Abstract: Indigenous fungi isolated from soil of a former gasworks site were investigated in submerged cultures with pyrene as the sole carbon source. Five fungal strains capable of degrading pyrene included one strain of Trichoderma harzianum and four strains with characteristics of the genus Penicillium. These are identified as Penicillium simplicissimum, Penicillium janthinellum, Penicillium funiculosum and Penicillium terrestre. A maximum of 75% of 50 mg l−1 and 67% of 100 mg l−1 of pyrene was removed by the fast degrading strain P. terrestre at 22°C during 28 days of incubation. The slower degrader P. janthinellum was able to remove 57% of 50 mg l−1 and about 31.5% of 100 mg l−1 pyrene. Degradation of pyrene is directly correlated with biomass development. To the best of our knowledge, this is the first time that fungi have been reported to use pyrene as the sole carbon and energy source. They may be ideal candidates for effective bioremediation of polycyclic aromatic hydrocarbons.

100 citations


DOI
29 Jan 2002
TL;DR: The current market for biological agents is estimated to be about 1% of the world’s total output for crop protection, but the largest share of this market involves biopesticides marketed for insect control (mainly products based on Bacillus thuringiensis).
Abstract: Despite many achievements in modern agriculture, food crop production continues to be plagued by disease-causing pathogens and pests. In many cases, chemical pesticides effectively protect plants from these pathogens. However, public concerns about harmful effects of chemical pesticides on the environment and human health have prompted a search for safer, environmentally friendly control alternatives (1–3). One promising approach is biological control that uses microorganisms capable of attacking or suppressing pathogens and pests in order to reduce disease injury. Biological control of plant pathogens offers a potential means of overcoming ecological problems induced by pesticides. It is an ecological approach based on the natural interactions of organisms with the use of one or more biological organisms to control the pathogen. Generally, biological control uses specific microorganisms that attack or interfere with specific pathogens and pests. Because of their specificity, different microbial biocontrol agents typically are needed to control different pathogens and pests, or the same ones in different environments. Agriculture benefits, and is dependent on, the resident communities of microorganisms for naturally occurring biological control, but additional benefits can be achieved by introducing specific ones when and where they are needed (4–9). Many agrochemical and biotechnological companies throughout the world are increasing their interest and investment in the biological control of plant diseases and pests. For plant pathogens alone, the current list of microbial antagonists available for use in commercial disease biocontrol includes around 40 preparations (9–11). These are all based on the practical application of seven species of bacteria (Agrobacterium radiobacter, Bacillus subtilis, Burkholderia cepacia, Pseudomonas fluorescens, Pseudomonas syringae, Streptomyces griseoviridis, Streptomyces lydicus) and more than 10 species of fungi (Ampelomyces quisqualis, Candida oleophila,Coniothyrium minitans, Fusarium oxysporum,Gliocladium virens, Phlebia gigantea, Pythium oligandrum, Trichoderma harzianum, and other Trichoderma species). The current market for biological agents is estimated at only $500 million, which is about 1% of the world’s total output for crop protection. The largest share of this market involves biopesticides marketed for insect control (mainly products based on Bacillus thuringiensis

99 citations


Journal ArticleDOI
TL;DR: Sequence analysis indicates the β-1,6-glucanase is homologous to enzymes secreted by the mycoparasitic fungi Trichoderma harzianum and Trichodma virens, and may have a nutritional role for the fungus.
Abstract: Mutualistic fungal endophytes infect many grass species and often confer benefits to the hosts such as reduced herbivory by insects and animals. The physiological interactions between the endophytes and their hosts have not been well characterized. Fungal-secreted proteins are likely to be important components of the interaction. In the interaction between Poa ampla and the endophyte Neotyphodium sp., a fungal β-1,6-glucanase is secreted into the apoplast, and activity of the enzyme is detectable in endophyte-infected plants. Sequence analysis indicates the β-1,6-glucanase is homologous to enzymes secreted by the mycoparasitic fungi Trichoderma harzianum and Trichoderma virens. DNA gel-blot analysis indicated the β-1,6-glucanase was encoded by a single gene. As a secreted protein, the β-1,6-glucanase may have a nutritional role for the fungus. In culture, β-1,6-glucanase activity was induced in the presence of β-1,6-glucans. From RNA gel blots, similar β-1,6-glucanases were expressed in tall fescue (Festuca arundinacea Schreb.) and Chewings fescue (Festuca rubra L. subsp. fallax [Thuill] Nyman) infected with the endophyte species Neotyphodium coenophialum and Epichloe festucae, respectively.

78 citations


Journal ArticleDOI
TL;DR: The capacity of the Trichoderma harzianum protease to hydrolyze the cell wall of C. perniciosa indicates that this enzyme may be actually involved in the antagonistic process between the two fungi, and strongly suggest that hydrolytic enzyme over-producing transgenic fungi may show superior biocontrol capacity.
Abstract: Several Trichoderma strains have been reported to be effective in controlling plant diseases, and the action of fungal hydrolytic enzymes has been considered as the main mechanism involved in the antagonistic process. However, although Trichoderma strains were found to impair development of Crinipellis perniciosa, the causal agent of cocoa plant witches' broom disease, no fungal strain is available for effective control of this disease. We have then undertaken a program of construction of hydrolytic enzyme-overproducing Trichoderma strains aiming improvement of the fungal antagonistic capacity. The protease of an indian Trichoderma isolate showing antagonistic activity against C. perniciosa was purified to homogeneity and characterized for its kinetic properties and action on the phytopathogen cell wall. A protease produced by the Trichoderma harzianum isolate 1051 was purified to homogeneity by precipitation with ammonium sulfate followed by hydrophobic chromatography. The molecular mass of this protease as determined by SDS-polyacrylamide gel electrophoresis was about 18.8 kDa. Its N-terminal amino acid sequence shares no homology with any other protease. The purified enzyme substantially affected the cell wall of the phytopathogen C. perniciosa. Western-blotting analysis showed that the enzyme was present in the culture supernatant 24 h after the Trichoderma started to grow in casein-containing liquid medium. The capacity of the Trichoderma harzianum protease to hydrolyze the cell wall of C. perniciosa indicates that this enzyme may be actually involved in the antagonistic process between the two fungi. This fact strongly suggest that hydrolytic enzyme over-producing transgenic fungi may show superior biocontrol capacity.

75 citations


Journal ArticleDOI
TL;DR: The laccases of the two fungal species exhibit comparable kinetic parameters, pH optima and thermal sensitivity but differed in physiological properties, such as their catalytic activity during growth.
Abstract: Laccase activity in Trichoderma harzianum and in our own isolate Trichoderma atroviride was correlated with the production of the green pigment in conidial spores. The laccases of the two fungal species exhibit comparable kinetic parameters, pH optima and thermal sensitivity but differed in physiological properties, such as their catalytic activity during growth.

Journal ArticleDOI
TL;DR: The biocontrol field trial suggested that the B. piricola canker on apple shoots and stems and rotting fruit had been efficiently controlled by the application of spore suspensions of T. atroviride T95.
Abstract: Trichoderma harzianum T88 and T. atroviride T95 were tested for their efficacy in controlling apple ring rot (caused by Botryosphaeria berengeriana f. sp. piricola) in vitro and in the field. Isolates of T88 and T95 produced both volatile and non-volatile antibiotics that suppressed mycelial growth of the pathogen. Light and scanning electron microscopy showed that mycoparasitism by Trichoderma spp. of B. berengeriana f. sp. piricola resulted in penetration and disruption of hyphal cells, and thinning of cytoplasm of the pathogen. The culture filtrates of T88 and T95 in Czapek's liquid medium suppressed conidial germination of the pathogen, and the germination level was negatively correlated with the duration of culture of Trichoderma. In inoculation tests, 32 days after simultaneous inoculation or preinoculation with B. berengeriana f. sp. piricola and Trichoderma spp., the incidence of infected apple shoots was reduced, respectively, by 65.3-76.4% and 62.5-76.4%, and the index of infection reduced by 36.9-38.9 and 40.7-44.4, The effect of inoculating B. berengeriana f. sp. piricola 3 days after the antagonists were inoculated was greater (81.4-88.8%) than simultaneous inoculation (72.2-77.8%). Re-isolation from inoculated apple shoots demonstrated that the pathogen had been suppressed by Trichoderma. The ability to re-isolate the pathogen from apple after co-inoculation and pre-inoculation with Trichoderma spp. was reduced by 27.0-42.3% and 22.2-47.1%, respectively. The biocontrol field trial suggested that the B. berengeriana f. sp. piricola canker on apple shoots and stems and rotting fruit had been efficiently controlled by the application of spore suspensions of T. harzianum T88 and T. atroviride T95. The efficacy of control by Trichoderma is thus similar to that of routine chemical control.

Journal ArticleDOI
TL;DR: Results indicated that both PAPA and beta-1,6-glucanase undergo proteolysis in ammonium-supplemented medium but PAP a is not responsible for beta- 1,6,glucAnase degradation.
Abstract: A gene that encodes an extracellular aspartyl protease from Trichoderma harzianum CECT 2413, papA, has been isolated and characterized. Based on several conserved regions of other fungal acid proteases, primers were designed to amplify a probe that was used to isolate the papA gene from a genomic library of T. harzianum. papA was an intronless ORF which encoded a polypeptide of 404 aa, including a prepropeptide at the N-terminal region formed by one putative signal peptide, a second peptide which could be cleaved to activate the enzyme and the active protease of calculated 36·7 kDa and pI 4·35. Northern experiments indicated that papA gene was pH regulated, repressed by ammonium, glucose and glycerol, and induced by organic nitrogen sources. The promoter possessed potential AreA, PacC and MYC sites for nitrogen, pH and mycoparasitism regulation respectively, but lacked potential CreA sites for carbon regulation. IEF and zymograms indicated that PAPA was a pepstatin-sensitive aspartyl protease of pI 4·5. Transformants from T. harzianum CECT 2413 cultivated in yeast extract-supplemented medium overexpressed papA and had a fourfold increase in protease activity compared to the wild-type, while transformants that overexpressed the β-1,6-glucanase gene bgn16.2 and papA had an additional 30% increase in β-1,6-glucanase activity compared to bgn16.2 single transformants. Overexpression of both genes in ammonium-supplemented medium did not result in higher levels of PAPA and/or BGN16.2 proteins. These results indicated that both PAPA and β-1,6-glucanase undergo proteolysis in ammonium-supplemented medium but PAPA is not responsible for β-1,6-glucanase degradation.

Journal ArticleDOI
TL;DR: The need to augment soil applications of T. harzianum for obtaining effective control of pigeonpea wilt is suggested, as the efficacy of the biological control agent Trichoderma harZianum was found to be more effective than seed treatment for disease suppression.

Journal ArticleDOI
TL;DR: Sugarcane bagasse was used as substrate for xylanase production by means of a strain of Trichoderma harzianum Rifai isolated from decaying Aspidosperma sp.

Journal ArticleDOI
TL;DR: Cultures derived from ascospores of Hypocrea lixii produced the morphological species Trichoderma harzianum in pure culture, which was confirmed by DNA sequence analysis.
Abstract: Cultures derived from ascospores of Hypocrea lixii (= H. nigricans, H. lentiformis) produced the morphological species Trichoderma harzianum in pure culture. Trichoderma harzianum, the most commonly found species of the genus, is also one of the most species frequently used in biocontrol of plant pathogens. It has not been connected previously to a teleomorph. The connection was confirmed by DNA sequence analysis. Similar to the anamorph, the teleomorph collections have a wide geographic distribution. Described in the 19th century, Hypocrea lixii is epitypified by a collection from Thailand.

Journal ArticleDOI
TL;DR: The study establishes that G. virens can be exploited for the biological control of wilt disease at field level by amending their inocula in pots and in pathogen-infested soil in the fields.
Abstract: Biological control of Fusarium udum causing wilt disease of pigeonpea was studied in vitro, as well as, in vivo. Aspergilluspavus, Anergillus niger, Bacilius licheniformis (strain-2042), Gliocladium virens, Peniciliium citrimum, and Trichoderma harzianum, which were found to be the most potent ones in inhibiting the radial colony growth of the test pathogen, were used as biological control by amending their inocula at diffeyent concentrations in pots and in pathogen-infested soil in the fields. Maximum reduction of the wilt disease was observed with G. vireos both in pots and in the fields. The population of E. udum was found to be markedly reduced when the antagonists were applied in the soil. The study establishes that G. virens can be exploited for the biological control of wilt disease at field level.

Journal Article
TL;DR: Soil application of these bioagents, one week before sowing found to be more effective than seed treatment in reducing wilt and wet root rot of chickpea and the two bioagents had positive effect on plant growth.
Abstract: Two antagonistic fungi viz., Trichoderma harzianum (PDBCTH 10) and T. viride (PDBCTV) were evaluated against natural incidence of wilt and wet root rot of chickpea in a field plot. Soil application of these bioagents, one week before sowing found to be more effective than seed treatment in reducing wilt and wet root rot of chickpea. The two bioagents had positive effect on plant growth. T. harzianum soil treated plots recorded only 4.9 and 1.2% root rot at 30 and 60 days respectively and was found to be superior to all other treatments. In pathogen check, the root rot incidence was 16.4 and 17.0% at 30 and 60 days respectively. Wilt incidence recorded was also high (11.8 and 16%) in control plots, but in T. harzianum soil treated plots only 4 and 5.1% wilt incidence was noticed at 60 and 90 days respectively. The seed yield recorded was significantly high in all treatments when compared to pathogen check and the highest yield of 965.4 kg/ha was obtained with soil treatment of T. harzianum.

Journal ArticleDOI
TL;DR: The secretion of beta-1,3-endoglucanases and/or proteases appeared to have less significance than endochitinases in the biological control of P. lycopersici, but the higher secretion of chit inases correlated well with its higher ability to control this agent in laboratory and greenhouse experiments.
Abstract: Four isolates of Trichoderma harzianum (ThN3, Th11, Th12 and Th16) were selected for their ability to control the in vitro development of the tomato root pathogen Pyrenochaeta lycopersici. Analysis of the mechanisms involved in biocontrol showed that the formation of non-volatile metabolites appears to be one of those involved in biocontrol of P. lycopersici by all T. harzianum isolates tested. Nevertheless, the higher secretion of chitinases, both in number of isoenzymes and activity by the Th11 strain, correlated well with its higher ability to control this agent in laboratory and greenhouse experiments as compared to the other T. harzianum isolates tested. The secretion of beta-1,3-endoglucanases and/or proteases appeared to have less significance than endochitinases in the biological control of P. lycopersici.

Journal Article
TL;DR: Increase in the total population density of T. harzianum in the media suggests that competition by native fungi in non-sterile carrier media was not a limiting factor in colonization of the media by the antagonist.
Abstract: Addition of Trichoderma herzienum into organic media like neemcake, coirpith, farmyard manure and decomposed coffee pulp caused an immediate increase in the population upto 3 days. Population increase was observed at all the different proportions of initial inoculum levels tried. It also showed similar trends at different locations. Increase in the total population density of T. harzianum in the media suggests that competition by native fungi in non-sterile carrier media was not a limiting factor in colonization of the media by the antagonist. Soil amended with organic materials like neemcake, coircompost, farmyard manure and Gliricidia leaves showed better growth and survival of antagonist than in soil alone. The carrier materials like neemcake, coirpith, farmyard manure and decomposed coffee pulp serve as nutrient additives to the crop in addition to inoculum production they support.

Journal Article
TL;DR: The antibiotic activity of 70 isolates belonging to the genera Aspergillus, Penicillium, Fusarium, Alternaria and Trichoderma was tested as preliminary screening and it is implied that metabolite production is involved in this antagonistic effect.
Abstract: The antibiotic activity of 70 isolates belonging to the genera Aspergillus, Penicillium, Fusarium, Alternaria and Trichoderma was tested as preliminary screening. The highest activity was obtained with three Penicillium oxalicum isolates, one Penicillium decumbens isolate and the Trichoderma harzianum isolate. After that, we chose these five isolates in order to carry out other studies with bacteria, fungi and insects. Extracts from these isolates were obtained. The extracts were tested for antibiotic activity with positive results, which implies that metabolite production is involved in this antagonistic effect. The highest activity was shown by T. harzianum and P. oxalicum extracts, but there was high variability among P. oxalicum isolates.

Journal ArticleDOI
TL;DR: A field experiment was carried out to investigate the biological control of R. solani by different organisms including bacteria and fungi and indicated that all the antagonists tested inhibited infection by R.solani and that the efficacy of prevention depended on the application method used.
Abstract: A field experiment was carried out to investigate the biological control of R. solani by different organisms including bacteria and fungi. Three methods of application were used during the study. Control results differed with the method of application used. The present study indicated that all the antagonists tested inhibited infection by R. solani and that the efficacy of prevention depended on the application method used. Coating sugarbeet seeds with antagonists was produced results for applying the antagonist to control R. solani. A soil preinoculation that contained the antagonist was better than treating them with extracts of antagonists although antimicrobial compounds in the extracts have been found to control the disease to the same extent. The most effective biocontrol agent was Trichoderma harzianum. Hyphal interactions between T. harzianum and R. solani were observed by scanning electron microscopy. T. harzianum attached to the host by hyphal coils. In Egypt, sugarbeet is attacked by several root-rot pathogens; the most serious of which are those caused by Rhizoctonia solani Kuhn and Sclerotium rolfsii Sacc. These two pathogenic fungi are subjected to two major environmental stresses: salinity and application of the herbicide pyradur for the control of weeds in sugarbeet. The impact of salinity stress on the pathogenicity and growth activities of these fungi has been studied (El-Abyad et al., 1988a,b). The impact of salinity and herbicide pyradur on pathogenicity and production of cell wall degrading enzymes by these fungi have been also studied (Moussa, 1994; El-Abyad et al.,

Journal ArticleDOI
TL;DR: A sensitive metabolic marker approach was developed that allowed for the continuous presence and activity of this fungal strain in the corn rhizosphere soil in situ over time and developed a dependable approach to introduce laboratory selected, pesticide-degrading microorganisms into soil environments for the purpose of in situ bioremediation.
Abstract: To develop a dependable approach to introduce laboratory selected, pesticide-degrading microorganisms into soil environments for the purpose of in situ bioremediation, we tested the possibility of utilizing plant rhizospheres as the vehicle. We first established the rhizosphere competency of a strain of the soil fungus Trichoderma harzianum, a biocontrol species well studied by plant pathologists to colonize plant rhizosphere in many parts of the world. The strain we chose, T.h.2023 is resistant to many fungicides, and it has been shown to metabolize several pesticides. Second, we found that it readily metabolized pentachlorophenol (PCP), which is quickly and stochiometrically converted to pentachloroanisole (PCA) in liquid culture. Taking advantage of this specific feature, we have developed a sensitive metabolic marker approach that allowed us to monitor for the continuous presence and activity of this fungal strain in the corn rhizosphere soil in situ over time.

Journal ArticleDOI
TL;DR: Evaluating liquid-liquid extractive fermentation systems as an alternative to overcome the toxicity problems and to increase the production of 6PP by this fungus found that even in the presence of the solvent, 6PP content decreased after reaching its maximal concentration.
Abstract: The final concentration of 6-pentyl-α-pyrone (6PP) produced in cultures of Trichoderma spp. is limited by the fact that inhibition of biomass growth occurs at 6PP concentrations as low as 100 mg/l. The aim of this work was to evaluate liquid-liquid extractive fermentation systems as an alternative to overcome the toxicity problems and to increase the production of 6PP by this fungus. Two alkanes (n-decane and n-hexadecane) and two dicarboxylic esters (dibutyl phthalate and dioctyl phthalate) were evaluated in shake flask cultures. The highest 6PP production (173 ppm) was achieved when n-hexadecane was used, being 3.5-fold the maximum 6PP concentration of a culture without the solvent. Cultivation of Trichoderma harzianum in a 10-l bioreactor with n-hexadecane yielded 6PP production ninefold higher than that from control cultures. However, 6PP production in the bioreactor (83 ppm) was lower than in shake flasks. Differences in the power drawn to the fluid at each scale could account for such behavior. Even in the presence of the solvent, 6PP content decreased after reaching its maximal concentration.

Journal Article
TL;DR: A biocontrol agent, T.harzianum, isolated from Sikkim was found effective in control of Ginger diseases substantially and the specific chemicals, targeted to particular pathogens ensured the involvement of different pathogens as well as effectiveness of chemicals on control of ginger was diseases.
Abstract: Ginger ( Zingiber officina/e Rosc.), is the second most important cash crop of Sikkim. Diseases are important production constraints and often associated with Ralstonia ( Pseudomonas) solanacearum, Pythium spp., Fusarium oxysporum and Praty/enchus coffeae. Pathogenicity experiments conducted, showed the involvement of Pythium sp (soft rot), Fusarium oxysporum (dry rot) and R.solanacearum ( wilt) and also noticed that, Praty/enchus coffeae increased the severity of infection along with F.oxysporum. From the indirect pathogenicity experiments, the specific chemicals, targeted to particular pathogens ensured the involvement of different pathogens as well as effectiveness of chemicals on control of ginger was diseases. A biocontrol agent, T.harzianum, isolated from Sikkim was found effective in control of ginger diseases substantially.

Journal ArticleDOI
TL;DR: Trichoderma harzianum Rifai application either to soil as wheat bran saw dust preparation or on the groundnut seeds as spore coat proved effective against selerotium wilt caused by Sclerotium rolfsii Sacc.
Abstract: Trichoderma harzianum Rifai application either to soil as wheat bran saw dust (WBSD) preparation or on the groundnut seeds as spore coat proved effective against selerotium wilt caused by Sclerotium rolfsii Sacc. Synergistic and positive effects on disease control were registered when T. harzianum -WBSD preparation was applied to soil in integration with Vitavax or Vitavax-200. Integration of Thiram (seed coating) and soil application of antagonist was found compatible and synergistic. However, seed treatment with both antagonist and Thiram was found incompatible and hence may not be practically feasible for disease reduction.

Journal ArticleDOI
TL;DR: The application of TrH 40 and potassium metabisulphite effectively controlled the incidence and severity of the three postharvest diseases and maintained the overall quality and color of the fruit under low temperature storage at 13.5°C and 95% r.h. for 18 days.
Abstract: Botryodiplodia theobromae, Colletotrichum gloeosporioides andGliocephalotrichum microchlamydosporum are the causal fungi of the rambutan postharvest diseases stem-end rot, anthracnose and brown spot, respectively. Two different treatments of rambutan fruits(Nephelium lappaceum) against the three pathogens were compared: potassium metabisulphite (250 ppm) or cinnamaldehyde (30 ppm), each combined withTrichoderma harzianum (TrH 40). The application of TrH 40 and potassium metabisulphite effectively controlled the incidence and severity of the three postharvest diseases and maintained the overall quality and color of the fruit under low temperature storage at 13.5°C and 95% r.h. for 18 days. The greatest effect of this treatment was shown onG. microchlamydosporum. Cinnamaldehyde affected the growth and germination of TrH 40, whereas potassium metabisulphite did not.

Journal ArticleDOI
TL;DR: Findings strongly suggest that the T. reesei ftt1 has a role in protein secretion, and FTTII is relatively distinct from FTTI, showing approximately 75% identity to other fungal 14-3-3 proteins.

Journal ArticleDOI
TL;DR: The use of FDA, with computer-aided quantitative image analysis, has made it possible to rapidly and reliably quantify the viability of T. harzianum.
Abstract: Fluorescence microscopy and image analysis were evaluated in order to assess the viability of Trichoderma harzianum, an economically important filamentous fungus. After the evaluation of the two most commonly used fluorochromes, acridine orange (AO) and fluorescein diacetate (FDA) as metabolic indicator stains, AO gave ambiguous results and therefore FDA was chosen. The lower stability at room temperature and fast fluorescence intensity decay (50% after only 30 s of illumination in UV light) could be overcome by the use of a digital image acquisition system including frame grabber and a video camera. Fresh (live) fungal hyphae emitted bright green fluorescence when stained with this dye (7.5 μg/L), whereas a total absence of fluorescence was observed when using sterilized (dead) fungal cells. Fresh cells were subjected to different lethal and sublethal treatments and the percentage of FDA stained fluorescent hyphae was then measured over the total hyphal area (% of FDA-stained area) by image analysis. At the same time, samples were cultivated in shake flasks in order to correlate this % of FDA-stained area with its growth rate, a functional indicator of viability. The linear correlation (r = 0.979) was: growth rate (g/L · h) = 2.25 × 10−3 (% of FDA-stained area). This method was used to evaluate the viability of the fungus under two different fermentation conditions in a 10-L bioreactor. Estimated viable biomass during fermentation was strongly influenced by the process conditions. The use of FDA, with computer-aided quantitative image analysis, has made it possible to rapidly and reliably quantify the viability of T. harzianum. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 677–684, 2002.