The improvement of competitive saprophytic capabilities of Trichoderma species through the use of chemical mutagens

Abstract The antagonistic potential of Trichoderma strains was assayed by studying the effect of their culture filtrate on the radial growth of Sclerotium rolfsii, the causal agent of chickpea collar rot. Trichoderma harzianum-1432 (42.2%) and Trichoderma atroviride (40.3%) were found to be strong antagonists. To enhance their antagonistic potential, mutagenesis of these two selected strains was performed. Two mutants, Th-m1 and T. atroviride m1, were found to be more effective than their parent strains. The enzymatic activities of the selected parent and mutant strains were assayed, and although both mutants were found to have enhanced enzymatic activities compared to their respective parent strains, Th-m1 possessed the maximum cellulase (5.69 U/mL) and β-1,3-glucanase activity (61.9 U/mL). Th-m1 also showed high competitive saprophytic ability (CSA) among all of the selected parent and mutant strains, and during field experiments, Th-m1 was found to successfully possess enhanced disease control (82.9%).

Morphological changes and growth of filamentous fungi in the presence of high concentrations of PAHs

In this study, we evaluated the effect of low and high molecular weight polycyclic aromatic hydrocarbons (PAHs), i.e., Phenanthrene, Pyrene and Benzo[a]pyrene, on the radial growth and morphology of the PAH-degrading fungal strains Aspergillus nomius H7 and Trichoderma asperellum H15. The presence of PAHs in solid medium produced significant detrimental effects on the radial growth of A. nomius H7 at 4,000 and 6,000 mg L⁻¹ and changes in mycelium pigmentation, abundance and sporulation ability at 1,000–6,000 mg L⁻¹. In contrast, the radial growth of T. asperellum H15 was not affected at any of the doses tested, although sporulation was observed only up to 4,000 mg L⁻¹ and as with the H7 strain, some visible changes in sporulation patterns and mycelium pigmentation were observed. Our results suggest that fungal strains exposed to high doses of PAHs significantly vary in their growth rates and sporulation characteristics in response to the physiological and defense mechanisms that affect both pigment production and conidiation processes. This finding is relevant for obtaining a better understanding of fungal adaptation in PAH-polluted environments and for developing and implementing adequate strategies for the remediation of contaminated soils.

Efficiency of treatments for controlling Trichoderma spp during spawning in cultivation of lignicolous mushrooms

Trichoderma spp is the cause of the green mold disease in mushroom cultivation production. Many disinfection treatments are commonly applied to lignocellulose substrates to prevent contamination. Mushroom growers are usually worried about the contaminations that may occur after these treatments during handling or spawning. The aim of this paper is to estimate the growth of the green mold Trichoderma sp on lignocellulose substrates after different disinfection treatments to know which of them is more effective to avoid contamination during spawning phase. Three different treatments were assayed: sterilization (121 ºC), immersion in hot water (60 and 80 ºC), and immersion in alkalinized water. Wheat straw, wheat seeds and Eucalyptus or Populus sawdust were used separately as substrates. After the disinfection treatments, bagged substrates were sprayed with 3 mL of suspension of conidia of Trichoderma sp (10(5) conidia/mL) and then separately spawned with Pleurotus ostreatus or Gymnopilus pampeanus. The growth of Trichoderma sp was evaluated based on a qualitative scale. Trichoderma sp could not grow on non-sterilized substrates. Immersions in hot water treatments and immersion in alkalinized water were also unfavorable treatments for its growth. Co- cultivation with mushrooms favored Trichoderma sp growth. Mushroom cultivation disinfection treatments of lignocellulose substrates influence on the growth of Trichoderma sp when contaminations occur during spawning phase. The immersion in hot water at 60 ºC for 30 min or in alkalinized water for 36 h, are treatments which better reduced the contaminations with Trichoderma sp during spawning phase for the cultivation of lignicolous species.

antifungal, cytotoxic, antitermite and insecticidal activities of zizyphus jujube

Plants are very useful, self-generating machines, producing a variety of useful bioactive products. Keeping in view this idea, the crude methanolic extract and various fractions of Zizyphus jujuba were screened for antifungal, cytotoxic, antitermite and insecticidal activities. Low activity was shown by the crude methanolic extract [12%], n-hexane [9%], chloroform [20%] and ethyl acetate [14%] fraction against Penicillium notatum. Low activity was shown by the ft-hexane fraction against Aspergillus niger [10%] and Trichoderma harzianum [13%] and inactive against Aspergillus flavus, Fusarium oxysporum and Rhizopus stolonifer. The CHC1[3] fraction exhibited low activity of 10% against F. oxysporum while showing no activity against the rest of the test fungi. All the test samples were inactive against Rhizopus stolonifer. The crude methanolic extract was highly cytotoxic [73.33%] at the concentration of 1000 [microg/ml] while the rest of the test samples were low in toxicity at the same concentration. The crude methanolic extract of Zizyphus jujuba showed significant antitermite activity against Heterotermes indicola, among the test samples. Against Tribolium castaneum, Rhizopertha dominica and Callosbruchus analis the insecticidal activity was determined. All the test samples except rc-hexane showed low activity [20%] against T. castaneum. The w-hexane fraction showed low activity [20%] against R. dominica while the rest of the fractions were inactive against it. Low activity of 40% and 20% was shown by the chloroform and "-hexane fraction respectively against C. analis. The results of the present study revealed that the plant could be as potent source of cytotoxic drugs

A study to evaluate the antimicrobial activity of feracrylum and its comparison with povidone-iodine.

Feracrylum, a water-soluble polymer of polyacrylic acid is known for its hemostatic property. Present work is an effort to evaluate its minimum inhibitory concentration (MIC) and compare it with the MIC of povidone-iodine. Ten different species of pathogenic microorganisms were selected, strains of which were obtained from Haffkine Institute. The organisms were maintained under appropriate culture media. The MIC of Freracrylum was determined by using tube culture method where its activity was compared against a standard antimicrobial agent providone-iodine. The study parameters showed that Feracrylum exhibits antimicrobial activity against a wide variety of microorganisms and its efficacy is comparable to that of povidone-iodine.

Induction of stable benomyl-tolerant phenotypic mutants of Trichoderma pseudokoningii MTCC 3011, and their evaluation for antagonistic and biocontrol potential.

Trichoderma pseudokoningii MTCC 3011 is a very useful strain for biological control of the plant pathogen Sclerotium rolfsii under post-harvest conditions. In the present investigation, several benomyl-tolerant phenotypic mutants of this strain have been generated using a two step mutagenesis-chemical followed by gamma irradiation. The mutants differed from the wild type strain in antibiotic and disease control potential. Some of the mutants are superior to the wild type in biocontrol potential on S. rolfsii.

Glygerol production under solute stress using the mixed culture of trichoderma viride and saccharomyces cerevisiae Y-1347

The effect of salt stress on the growth parameters of S.cerevisiae Y-1347 was studied by using Nacl. The increase in Nacl level was accompanied by a parallel increase in the efficiency of the cultures to convert glucose to glycerol. Maximum glycerol and glycerol phosphate dehydrogenase production [700 mg/l00ml and 198 U/ml respectively] were achieved with 5.8 g% Nacl 3% [W/V] NaHSO[3] and 1 g/l beef extract in presence of tween 80 with a[w] = 0.24k[-1]

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.