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Haran, S., Schickler, H., Chet, I. (1996) Molecular mechanisms of lytic enzymes involved in the biocontrol activity of Trichoderma harzianum. Microbiology 142 , 2321-2331. Molecular
Potential virulence factors of 9 saprophytic and 12 clinical Trichoderma longibrachiatum strains were examined in the present study, in order to compare their capacity to cause infection in humans. All of the strains were able to grow at temperatures up to 40 °C and at pH values ranging from 2.0 to 9.0. Carbon and nitrogen source utilization experiments revealed that all of the strains were able to utilize a series of basic amino acids both as sole carbon and nitrogen sources. The MIC values of the tested antifungal drugs were found to be 0.016-8 µg/ml for amphotericin B, 64-256 µg/ml for fluconazole, 0.5-32 µg/ml for itraconazole and 0.008-1 µg/ml for ketoconazole in the case of the examinedis olates. Metabolites of the strains inhibited the growth of different bacteria, furthermore, compounds produced by three clinical isolates reduced the motility of boar spermatozoa, indicating their toxicity to mammalian cells as well. On the whole, there were no significant differences in the examined features between strains derived from clinical or soil samples. The question, however, whether all environmental Trichoderma longibrachiatum strains have the capacity to cause infections or not, remains still unanswered.
Cadmium, nickel or zinc contaminated soils originating from a long-term heavy metal field experiment were used to assess the influence of those particular treatments on the coexistence of various Trichoderma species. The abundance of six indigenous Trichoderma spp. - T . atroviride , T . harzianum , T . pubescens , T . tomentosum , T . virens and T . viride - were studied 12 years after the application of Cd, Zn and Ni salts on four levels (0, 30, 90 and 270 mg·kg -1 ) in a calcareous chernozem soil. Trichoderma fungal colonies from the soil particles were estimated on selective media. The isolated strains were taxonomically characterized by microscopic visualization. A reduced Trichoderma fungal colonization was found at the lower ratio of the studied metals. No colonization could be recorded in the case of Cd, and a slightly increased abundance at Ni and Zn metal salts at the highest 270 mg·kg -1 doses. The species composition of the fungi varied considerably in the contaminated samples as a function of the metals and the applied doses. Correlation analysis revealed that the population density of T . atroviride , T . harzianum , T . pubescens , T . viride was negatively affected by the available Cd concentration. The nickel content of the soil, however, correlated positively with the abundance of T . harzianum (r = 0.955) and T . virens (r = 0.964). In addition to this finding, the frequency of T . viride and T . tomentosum showed significant positive and negative correlation with the Zn treatment (r = 0.955; r = -0.965, respectively). Great differences between the correlation and partial correlation coefficients suggested that the heavy metals may alter not only the abundance of the fungi, but the interspecific relationships among the indigenous Trichoderma population, as well. This fact is considered to have further influence on some other biotic parameters and the soil functioning in heavy-metal-affected soils.
. 8 52 60 Benítez, T., Villa, T. G., García-Acha, I. (1975) Chemical and structural differences in mycelia and regeneration walls of Trichoderma
Effect of Trichoderma viride T1433 on the pectolytic enzyme activity of Rhizopus stolonifer (= R. artocarpi) during the development of soft rot of jackfruit was studied. Activity of different fractions of pectolytic enzymes like PG, PME and PL was investigated during pathogenesis and correspondingly the associated resistance of the host was assayed. It was noticed that the biocontrol agent, Trichoderma significantly interacts with the pectolytic enzyme activity of the pathogen. It caused an appreciable reduction in enzymatic action. The reduction in the activity of polygalacturonase enzyme (PG) was recorded to be the highest among all the fractions of pectolytic enzymes. Such a trend appeared to be more pronounced in 'Kujja' than in 'Ghula' cultivar of jackfruit. The reduction in pectolytic enzyme activity was found to be coupled with a significant increase in the activity of polyphenol oxidase enzyme of the host tissues and a concomitant increase in host phenol content. Such inter-relationship between these two enzyme systems plays a key role to stimulate the defense mechanism of the host plant against infection. Significant increase in total phenol content of the host tissue during Trichoderma plant pathogen interaction that was recorded may correspond with the host defense response.
The purpose of this study was to survey the growth inhibition with volatile antibiosis and killing of Pythium irregulare by Trichoderma species of various origin under heavy metal stress. Fourteen strains of T. harzianum, 10 strains of T. virens, and 14 strains of T. viride were tested in dual culture with the pathogen on heavy metal poisoned media. Minimum inhibitory concentrations (MIC) for mycelial growth, antibiosis and Pythium-killing were determined. Although the decreasing order of toxicity (Cd≯Ni≯Zn) was the same for the growth of Pythium and the antagonists, the pathogen tolerated 2-4 times higher doses of toxic metals than Trichoderma strains did. The antagonistic activities proved to be more sensitive, they were blocked by 0.16-0.67 mM Cd, 0.16-1.25 Ni or Zn. Pythium-killing was observed at higher doses of Ni than that of Cd or Zn, which were similar toxic to the both investigated activities. The history of long-term heavy metal exposure of some investigated Trichoderma strains did not increase the tolerance of mycelial growth, but the antagonistic activities were more sensitive in those strains that had originated from not polluted arable soils.
Study and comparison of efficiency of the antagonist species Trichoderma atroviride, T. harzianum and T. longibrachiatum against Fusarium wilt were carried out using in vitro and in vivo based bioassay. Significant decrease of both growth and conidia production of the pathogen are obtained compared to the control. Thus, the highest percentages of diameter colony reduction and conidial production were obtained with the T. atroviride isolate (Ta.13), causing 65.64% reduction in colony diameter (direct confrontation), 48.71% reduction in colony diameter (indirect confrontation), and a complete inhibition of conidial production. Once more in direct confrontation, T. atroviride overgrowth the pathogen colony and sporulate above. The seed treatment by Trichoderma spp. isolates before sowing in a soil already infested by the pathogen led to a significant decrease of disease severity compared to the untreated control. The weakest index of disease severity is obtained with the T. atroviride isolates (Ta.13), which cause 83.92% reduction compared to the control. The most effective isolates in protection chickpea seedlings against the disease were the three strains of T. atroviride species (Ta.3, Ta.7 and Ta.13) as well as the isolate T. harzianum (Th.16). Reduction of disease severity obtained was associated with an increase of the vegetal growth including the stem height as well as the plant fresh and dry weight.
Aquatic weed water hyacinth was evaluated for its potential to be used as feedstock for fermentable sugar production via enzymatic hydrolysis. Critical factors (pretreatment of substrate, concentration of substrate, incubation period, pH, incubation temperature) affecting enzymatic hydrolysis of water hyacinth were optimised for maximum production of fermentable sugars. Enzyme (mainly cellulase) produced by Trichoderma reesei ATCC 26921 in a simple medium containing the plant biomass as the sole carbon source was directly used at a particular concentration for hydrolysis. It was observed that acid-alkali pretreated water hyacinth was far more accessible to cellulolytic enzymes than untreated one and hence was hydrolyzed to a greater extent. Maximum hydrolysis (41.7%) was obtained with 4% (w/v) pretreated water hyacinth after 72 h of incubation at pH 5.2 and at a temperature of 45 °C. With a view to enhance the percentage of enzymatic hydrolysis, culture metabolite (enzyme source) of T. reesei was supplemented with enzyme from a β-glucosidase mutant, Aspergillus phoenicis . This β-glucosidase enriched cellulase preparation facilitated further enhancement (49.7%) of hydrolysis at FPase to β-glucosidase ratio of 1:1.2. Gas-liquid-chromatographic analysis of the hydrolyzed broth, thus obtained under optimal conditions, revealed the presence of glucose (12.5 g l −1 ) as the most predominant fermentable sugar besides having the presence of xylose, arabinose, mannose and galactose. This widens up the feasibility of utilising such hydrolysate as a cheap carbon source (glucose and to some extent xylose) for yeast fermentation to produce fuel ethanol.
Udayasoorian, C., Govindasamy, K. N., Subbian, P. (1977): Effect of Trichoderma viride , additional nitrogen and farmyard manure on the productivity and sustainability of rice (Oryza sativa) -rice
The damage caused by root-knot nematodes (Meloidogynidae) (irregular galls of different sizes on the plant roots) is a general problem in greenhouses in Hungary.The effect of Trifender microbiological preparation has been investigated on the degree of damage caused by root-knot nematodes in green-house pepper. We set up our experiment in Pusztamonostor (Jászság region, Hungary) in a family farm in 2008 and 2009. We carried out preliminary evaluation (Zeck-scale; 0–10) in the precrop with symptomatic assessment. According to the preliminary evaluation, the infection showed rates of 2–3 on the average.The results of 2008 show that Trifender had no effect on the number of females, but the plant height has been increased by 12 and 15%, and yield has grown by 25–35%. But on the contrary, in 2009 the number of females was decreased by 33%, and plant height was increased by 11%.
