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PubMed2002

Synergism between fungal enzymes and bacterial antibiotics may enhance biocontrol.

The interactions between biocontrol fungi and bacteria may play a key role in the natural process of biocontrol, although the molecular mechanisms involved are still largely unknown. Synergism can occur when different agents are applied together, and cell wall degrading enzymes (CWDEs) produced by fungi can increase the efficacy of bacteria. Pseudomonas spp. produce membrane-disrupting lipodepsipeptides (LDPs) syringotoxins (SP) and syringomycins (SR). SR are considered responsible for the antimicrobial activity, and SP for the phytotoxicity. CWDEs of Trichoderma spp. synergistically increased the toxicity of SP25-A or SRE purified from P. syringae against fungal pathogens. For instance, the fungal enzymes made Botrytis cinerea and other phytopathogenic fungi, normally resistant to SP25-A alone, more susceptible to this antibiotic. Pseudomonas produced CWDEs in culture conditions that allow the synthesis of the LDPs. Purified bacterial enzymes and metabolites were also synergistic against fungal pathogens, although this mixture was less powerful than the combination with the Trichoderma CWDEs. The positive interaction between LDPs and CWDEs may be part of the biocontrol mechanism in some Pseudomonas strains, and co-induction of different antifungal compounds in both biocontrol bacteria and fungi may occur.

Cell Wall↗

PubMed2002

Pseudomonas lipodepsipeptides and fungal cell wall-degrading enzymes act synergistically in biological control.

Pseudomonas syringae pv. syringae strain B359 secreted two main lipodepsipeptides (LDPs), syringomycin E (SRE) and syringopeptin 25A (SP25A), together with at least four types of cell wall-degrading enzymes (CWDEs). In antifungal bioassays, the purified toxins SRE and SP25A interacted synergistically with chitinolytic and glucanolytic enzymes purified from the same bacterial strain or from the biocontrol fungus Trichoderma atroviride strain P1. The synergism between LDPs and CWDEs occurred against all seven different fungal species tested and P. syringae itself, with a level dependent on the enzyme used to permeabilize the microbial cell wall. The antifungal activity of SP25A was much more increased by the CWDE action than was that of the smaller SRE, suggesting a stronger antifungal role for SP25A. In vivo biocontrol assays were performed by using P. syringae alone or in combination with T. atroviride, including a Trichoderma endochitinase knock-out mutant in place of the wild type and a chitinase-specific enzyme inhibitor. These experiments clearly indicate that the synergistic interaction LDPs-CWDEs is involved in the antagonistic mechanism of P. syringae, and they support the concept that a more effective disease control is given by the combined action of the two agents.

Cell Wall↗

PubMed2001

Weeding and grooming of pathogens in agriculture by ants.

The ancient mutualism between fungus-growing ants and the fungi they cultivate for food is a textbook example of symbiosis. Fungus-growing ants' ability to cultivate fungi depends on protection of the garden from the aggressive microbes associated with the substrate added to the garden as well as from the specialized virulent garden parasite Escovopsis. We examined ants' ability to remove alien microbes physically by infecting Atta colombica gardens with the generalist pathogen Trichoderma viride and the specialist pathogen Escovopsis. The ants sanitized the garden using two main behaviours: grooming of alien spores from the garden (fungus grooming) and removal of infected garden substrate (weeding). Unlike previously described hygienic behaviours (e.g. licking and self-grooming), fungus-grooming and garden-removal behaviours are specific responses to the presence of fungal pathogens. In the presence of pathogens, they are the primary activities performed by workers, but they are uncommon in uninfected gardens. In fact, workers rapidly eliminate Trichoderma from their gardens by fungus grooming and weeding, suggesting that these behaviours are the primary method of garden defence against generalist pathogens. The same sanitary behaviours were performed in response to the presence of the specialist pathogen Escovopsis. However, the intensity and duration of these behaviours were much greater in this treatment. Despite the increased effort, the ants were unable to eliminate Escovopsis from their gardens, suggesting that this specialized pathogen has evolved counter-adaptations in order to overcome the sanitary defences of the ants.

Animals↗

PubMed1994

A newly isolated lectin from the plant pathogenic fungus Sclerotium rolfsii: purification, characterization and role in mycoparasitism.

A novel lectin was isolated and purified from the culture filtrate of the soilborne plant pathogenic fungus Sclerotium rolfsii by anion-exchange chromatography using a DEAE-Sepharose column. The lectin came through the column with the flow-through, whereas all the non-agglutinating proteins present in the crude preparation remained bound to the column until elution in a NaCl gradient. SDS-PAGE analysis of the agglutinating fraction revealed a single band corresponding to a protein with a molecular mass of approximately 45 kDa. Agglutination of Escherichia coli cells by the purified lectin was not inhibited by any of the mono- or disaccharides tested, whereas the glycoproteins mucin and asialomucin did inhibit agglutination. Proteases, as well as 1,3-beta-glucanase, were found to be totally destructive to agglutination activity, indicating that both protein and 1,3-beta-glucan are necessary for agglutination. Using a biomimetic system based on binding of the lectin to the surface of inert nylon fibres revealed that the presence of the purified agglutinin on the surface of the fibres specifically induced mycoparasitic behaviour in Trichoderma harzianum. Trichoderma formed tightly adhering coils, which were significantly more frequent with the purified agglutinin-treated fibres than with untreated ones or with those treated with non-agglutinating extracellular proteins from S. rolfsil. Other mycoparasite-related structures, such as appressorium-like bodies and hyphal loops, were only observed in the interaction between T. harzianum and the purified agglutinin-treated fibres.

Escherichia coli↗

PubMed1999

The enzymatic activity of fungal xylanase is not necessary for its elicitor activity.

Fungal xylanases from Trichoderma spp. are potent elicitors of defense responses in various plants. To determine whether enzymatic activity is necessary for elicitor activity, we used site-directed mutagenesis to reduce the catalytic activity of xylanase II from Trichoderma reesei. For this, the glutamic acid residue at position 210, which is part of the active center in this family of enzymes, was changed to either aspartic acid (E210D) or serine (E210S). Wild-type and mutated forms of xylanase II were expressed in yeast cells and purified to homogeneity. Compared with the wild-type form of xylanase II, E210D had >100-fold and E210S 1,000-fold lower enzymatic activity. In contrast, these mutated forms showed no comparable drop in elicitor activity. They fully stimulated medium alkalinization and ethylene biosynthesis in suspension-cultured tomato (Lycopersicon esculentum) cells, as well as hypersensitive necrosis in leaves of tomato and tobacco (Nicotiana tabacum) plants. These results provide direct evidence that enzyme activity is not necessary for elicitor activity of fungal xylanase.

Amino Acid Sequence↗

PubMed2006

Enhanced elution of sperm from cotton swabs via enzymatic digestion for rape kit analysis.

This report describes development of a method for enhanced cell elution from cotton swabs. The method exploits an enzyme mixture for digestion of the cotton to remove intact cells, and can be utilized in conjunction with or to circumvent conventional differential extraction (DE). Samples digested with Aspergillus niger cellulase yielded sperm cell recoveries (18+/-3.5%) similar to conventional DE buffer (23+/-7.8%) while providing intact epithelial cells. Storage time affected the concentration of enzyme required for optimal sperm cell recovery, with longer times requiring increased cellulase concentrations. Cellulase from A. niger yielded a twofold enhancement in sperm cell elution over buffer alone, and preliminary testing of higher activity cellulases from Trichoderma reesei and Trichoderma viride showed even greater enhancement. These results indicate that cellulose-digesting enzymes enhance the release of sperm and epithelial cells from a cotton swab over buffer alone, providing for efficient DNA analysis.

Aspergillus niger↗

PubMed2006

Cross talk between a fungal blue-light perception system and the cyclic AMP signaling pathway.

Blue light regulates many physiological and developmental processes in fungi. In Trichoderma atroviride the complex formed by the BLR-1 and BLR-2 proteins appears to play an essential role as a sensor and transcriptional regulator in photoconidiation. Here we demonstrate that the BLR proteins are necessary for carbon deprivation induced conidiation, even in the absence of light, pointing to the existence of an unprecedented cross talk between light and carbon sensing. Further, in contrast to what has been found in all other fungal systems, clear BLR-independent blue-light responses, including the activation of protein kinase A (PKA) and the regulation of gene expression, were found. Expression of an antisense version of the pkr-1 gene, encoding the regulatory subunit of PKA, resulted in a nonsporulating phenotype, whereas overexpression of the gene produced colonies that conidiate even in the dark. In addition, overexpression of pkr-1 blocked the induction of early light response genes. Thus, our data demonstrate that PKA plays an important role in the regulation of light responses in Trichoderma. Together, these observations suggest that the BLR complex plays a general role in sensing environmental cues that trigger conidiation and that such a role can be separated from its function as a transcription factor.

Cyclic AMP↗

PubMed1977

beta-Glucosidase: microbial production and effect on enzymatic hydrolysis of cellulose.

The enzymatic conversion of cellulose is catalyzed by a multiple enzyme system. The Trichoderma enzyme system has been studied extensively and has insufficient beta-glucosidase (EC 3.2.1.21) activity for the practical saccharification of celluose. The black aspergilli (A. niger and A. phoenicis) were superior producers of beta-glucosidase and a method for production of this enzyme in liquid culture is presented. When Trichoderma cellulase preparations are supplemented with beta-glucosidase from Aspergillus during practical saccharifications, glucose is the predominant product and the rate of saccharification is significantly increased. The stimulatory effect of beta-glucosidase appears to be due to the removal of inhibitory levels of cellobiose.

Aspergillus↗

PubMed2026

Endophytic fungi isolated from coffee plants promote Arabidopsis thaliana growth and suppress soil-borne fungal pathogens.

Endophytic beneficial microorganisms are widely used in agriculture for promoting plant growth and enhancing plant defense mechanisms. This study aimed to characterize endophytic fungi isolated from the roots of coffee plants cultivated in organic agroforestry systems and evaluate their potential as biocontrol agents against fungal pathogens, as well as their ability to promote plant growth. Biocontrol activity was assessed using in vitro dual-culture assays on potato dextrose agar, measuring the inhibition of pathogen growth. Plant growth promotion was evaluated by co-cultivating Arabidopsis thaliana seedlings with fungal isolates on Murashige and Skoog medium. Isolates were further subjected to both qualitative and quantitative biochemical characterization. A total of 18 endophytic fungal strains were identified and classified in five genera: Colletotrichum, Fusarium, Simplicillium, Lasiodiplodia and Trichoderma. Among these, ten Trichoderma isolates demonstrated strong antagonistic activity against selected fungal pathogens and significantly enhanced the growth of Arabidopsis seedlings in vitro. These beneficial effects were associated with the production of siderophores and indole-3-acetic acid, as well as the apparent nitrogen availability -- likely mediated through interactions with nitrogen-fixing bacteria.

Arabidopsis↗

PubMed1994

Application of the random amplified polymorphic DNA using the polymerase chain reaction for efficient elimination of duplicate strains in microbial screening. I. Fungi.

For efficient fungal strain selection in microbial screening, we applied the random amplified polymorphic DNA (RAPD) method using the polymerase chain reaction (PCR). In order to evaluate this system, the genus Trichoderma was employed, because its species are difficult to distinguish from each other. We selected an appropriate oligonucleotide decamer, R28 (5'-ATGGATCCGC), determined the optimal cycles of PCR as 30 cycles, simplified the template preparation method, and determined optimal concentrations of the template and Taq DNA polymerase. We then examined 74 closely related strains of Trichoderma. The electrophoretic band patterns of the PCR products were compared. According to the statistical analysis with the phylogenetic analysis using parsimony (PAUP), the results were consistent with the morphological, physiological and ecological data on these strains. Therefore, we conclude that RAPD is a simple, efficient and reliable method for the selection of fungal strains employed in screening.

Base Sequence↗

PubMed1975

Non-ribosomal biosynthesis of the cyclic octadecapeptide alamethicin.

The biosynthesis of the cyclic octadecapeptide, alamethicin, in a cell-free system of Trichoderma viride has been investigated. It was shown that nucleic acid- and ribo-some-free extracts of Trichoderma viride could catalyze alamethicin biosynthesis. Puromycin, erythromycin and RNAse did not inhibit this synthesis. The Sephadex G 200 filtrate contains a fraction (Kav=0.1) that catalyzes the biosynthesis of alamethicin and shows an ATP-32PPi exchange with 6 of the 8 constituent amino acids of alamethicin. The activated amino acids are bound to the enzyme as aminoacyl adenylates and as thiolesters in a proportion of 1 : 1. About 50% of each bound amino acid could be split off with 7% TCA. The TCA-stable bound amino acid could be split by mercury acetate, hydroxylamine and performic acid. N-ethylmaleimide blocked the binding of 50% of the amino acids to the enzyme, proving that some of the amino acids first bound as aminoacyl adenylates are then transferred into a thiolester bond.

Adenosine Monophosphate↗

PubMed2002

[Purification and characterization of antifungal proteins in triticale seed].

Using Trichoderma as an indicative fungus, three antifungal proteins in Triticale Zhongsi 237 seed were purified and characterized. These protein components were considered to be a new Class II chitinase and two kinds of beta-1, 3-glucanases. Chitinase molecular mass was 30.5 kD and enzyme activity was maximal at pH 6.0 and 37 degrees C. Two beta-glucanases molecular masses were 51 kD and 23 kD. N-terminal amino acid sequences of Triticale chitinase share high homology with barley chitinase. In some conditions, the chitinase and beta-glucanases all had strong antifungal activity and were able to inhibit Trichoderma growth synergistically. Moreover, the chitinase and beta-1, 3-glucanases were able to inhibit powdery mildew growth on detached susceptible wheat leaves.

Antifungal Agents↗

PubMed2003

Efficacy of different fungicides against Rhizoctonia brown patch and Pythium blight on turfgrass in Italy.

Brown patch, incited by Rhizoctonia solani Kuhn, and Pythium blight, caused by Pythium spp. are two of the diseases most frequently observed on turfgrass in high maintenance stands, as on golf courses. In such conditions the control strategies, based on chemicals, are particularly difficult due to the scarcity of fungicides registered for turf in Italy. The results obtained in experimental trials carried out to evaluate the efficacy of chemical and biological products against brown patch and Pythium blight are reported. On mature turfgrass, maintained under fairway conditions, azoxystrobin, and trifoxystrobin, not yet registered on turf, were very effective against brown patch. Tebuconazole, applied in three different formulations, was very effective against R. solani, while Trichoderma spp. and azadiractine did not control the pathogen. In greenhouse conditions on Agrostis stolonifera, in the presence of severe disease incidence, due to artificial inoculation, benalaxyl-M satisfactorily controlled Pythium blight; Trichoderma spp. as well as a commercial formulation of T. harzianum, applied one week before the inoculation, were not effective. Among the fungicides not yet registered for use on turfgrass in Italy, metalaxyl-M + mancozeb was effective against Pythium blight.

Fungicides, Industrial↗

PubMedDate not supplied

[New cellulases efficiently hydrolyzing lignocellulose pulp].

Commercial and pilot enzyme preparations from fungi of the genera Penicillium and Trichoderma have been compared with regard to their action on conifer wood pretreated with acidified aqueous ethanol (organosolve). In most experiments, enzymes from the genus Penicillium allowed higher yields of reducing sugars and glucose than those from Trichoderma. High beta-glucosidase activity is essential for deep pulp hydrolysis.

Cellulases↗

PubMed1991

Antifungal activity and mode of action of saponins from Madhuca butyracea Macb.

The antifungal activity of saponins isolated as a byproduct from the defatted cake of M. butyracea oil seed is reported. The inhibitory concentrations against plant pathogenic fungi ranged from 500 to 2000 ppm. Maximum sensitivity to saponins was shown by Penicillium expansum. Cephalosporium acrimonium, Helminthosporium oryzae and Trichoderma viride. The saponins caused leakage of cell components and underwent degradation by fungus, Trichoderma viride. The usefulness of saponins as antimycotic agents is discussed.

Antifungal Agents↗

PubMedDate not supplied

[Ortho-dianizidine micromethod of determining L-phenylalanine-alpha-oxidase activity].

A micromethod is developed for estimation of 1-phenylalanine-alpha-oxidase activity from Trichoderma sp. The method is based on interaction of H2O2 formed in the reaction with o-dianisidine.HCl. Optimal conditions were adopted for estimation of the new enzyme activity from Trichoderma sp. The enzyme had Km = 2.5.10(-3) M and Vmax = 0.42 U/mg at 20 mM concentration of phenylalanine in the incubation mixture; the highest enzymatic activity was estimated in citrate buffer, pH 5.0. The method is simple, precise and reproducible.

Amino Acid Oxidoreductases↗

PubMed1981

[Microflora in corn silage].

A total of 1050 samples of maize silage taken at various depths on premises for storing ensilaged feeds. The presence of eight species of microscopic fungi was demonstrated in the sampled silage: Mucor, Penicillium, Aspergillus, Alternaria, Trichoderma. It was established that highest was the number of species in the surface layer of the ensilaged mass. Considerably less were the species at a depth of 1.5 m, and then again the number of species rose toward the ground layer of silage. It is believed that lactic acid fermentation and the aerobic conditions exerted mycostatic effects. It was also demonstrated that with the aging of silage fungal species of the Fusarium and Trichoderma genera disappeared.

Alternaria↗

PubMed1993

Cellulase production on high levels of cellulose and corn steep liquor.

Several enhanced cellulase mutants of Trichoderma reesei have been used for cellulase production using corn steep liquor and microcrystalline cellulose as substrates. Under the optimum fermentation conditions on 6% cellulose and 3.6% corn steep liquor Trichoderma reesei Rut C 30 produced high levels of cellulase enzymes 6MC-ase 54 IU/ml, filter paper activity 3.2 IU/ml after 10 days incubation at 28-30 degrees C.

Ammonium Sulfate↗