Trichoderma Enzymes for Degradation of Aflatoxin B1 and Ochratoxin A.

The contamination of agricultural products with mycotoxins causes risks to animal and human health and severe economic losses. Mycotoxicoses can be reduced by preventing fungal infection using chemical and biological approaches. The chemical strategies can release toxic molecules; therefore, strategies for biological control are being evaluated, such as using nontoxic fungi and their metabolites. This work evaluated the effect of exoenzymes produced by the beneficial fungus Trichoderma afroharzianum strain T22 in degrading Aflatoxin B1 (AFB1) and Ochratoxin A (OTA). The ability of Trichoderma to produce hydrolases was stimulated by using different inducing substrates. The highest AFB1 and OTA degradation activity was obtained using a medium containing lyophilized mushrooms and crude fiber. The T. afroharzianum T22's ability to reduce mycotoxins may be attributed to peroxidase enzymes. This study showed that T. afroharzianum strain T22 or its peroxidase supplementation could represent a sustainable strategy for the degradation of AFB1 and OTA in feed and food products

Antifungal saponins from bulbs of white onion, Allium cepa L.

Three saponins, named ceposide A, ceposide B, and ceposide C were isolated from the bulbs of white onion, Allium cepa L. Elucidation of their structure was carried out by comprehensive spectroscopic analyses, including 2D NMR spectroscopy and mass spectrometry, and chemical evidences. The structures of the compounds were identified as (25R)-furost-5(6)-en-1b,3b,22a,26-tetraol 1-O-b-D-xylopyranosyl 26-O-a-D-rhamnoyranosyl-(1 ?2)-O-b-D-galactopyranoside (ceposide A), (25R)-furost-5(6)-en-1b,3b,22a,26-tetraol 1-O-b-D-xylopyranosyl 26-O-a-D-rhamnoyranosyl-(1 ?2)-O-b-D-glucopyranoside (ceposide B), and (25R)-furost-5(6)-en-1b,3b,22a,26-tetraol 1-O-b-D-galactopyranosyl 26-O-a-D-rhamnoyranosyl-( 1?2)-O-b-D-galactopyranoside (ceposide C). The isolated compounds, alone and in combinations, were evaluated for their antimicrobial activity on ten fungal species. Antifungal activity of all three saponins increased with their concentration and varied with the following rank: ceposide B > ceposide A–ceposide C. We found a significant synergism in the antifungal activity of the three ceposides against Botrytis cinerea and Trichoderma atroviride, because growth of these fungi was strongly inhibited when the three saponins were applied in combination. In contrast, Fusarium oxysporum f. sp. lycopersici, Sclerotium cepivorum and Rhizoctonia solani were very little affected by saponins

Effect of peeling and heating on carotenoid content and antioxidant activity of tomato and tomato-virgin olive oil systems

The effects of peeling and laboratory- or industrial-scale heating on carotenoid content and radical scavenging activity of tomato and tomato-virgin olive oil mixtures were investigated. A decrease in carotenoid content was detected only after long heating times. Such a decrease was lower for the unpeeled than for the peeled tomatoes. No change, either in lycopene concentration or in the chain-breaking activity of the lipophilic fractions, was observed when both laboratory- and industrial-scale heating treatments were performed on peeled-tomato puree containing 5% virgin olive oil. The aqueous fractions, including high-molecular-weight brown polymers formed as a consequence of heating, were also characterized for color, elementary composition and antioxidant activity

Enzymes produced by antagonist fungi can be effectively applied as new biopesticides

Antagonistic fungi of the genera Trichoderma and Gliocladiumsecrete complex enzyme mixtures (chitinases, glucanases, cellulasesand proteases) capable of lysing the cell wall of plant pathogenicfungi and showing a strong antifungal activity. In vitro experimentshad previously shown that these synergistic mixturescan also increase the toxic effect on phytopathogens of chemicalfungicides, thus eventually reducing their application dose. In thiswork, performed within the framework of the EU project ‘Substitutionof methyl bromide fumigation and disease management instrawberry crops by IPM strategies’, different Trichoderma strainsand culture conditions have been tested, and an efficient systemto produce potent combinations of fungicidal enzymes has beendeveloped. The dialyzed culture filtrates, characterized by thepresence of the lytic enzymes, have been applied directly in vivoto control Botrytis cinerea and Colletotrichum acutatum on strawberry,both on fruit in post harvest and on plants growing ingreenhouse. In addition, in vivo synergistic interactions with severalchemical fungicides have been identified, and protocols forjoint application and formulation of enzymes and fungicides have been developed

GENETIC IMPROVEMENT OF ANTAGONISTIC FUNGI AND THEIR ABILITY TO INDUCE SYSTEMIC DISEASE RESISTANCE IN THE PLANT

The interaction between Trichoderma spp., other soil or leafmicrobes (including phytopathogens) and the plant is much morecomplex than it was thought. These beneficial fungi seem to havethe remarkable ability to function at the same time both as microbialantagonists and plant symbionts, by using a variety of molecularfactors and specialized structures. For example, seed treatmentswith various Trichoderma strains provide increased resistanceto infection on the leaves by Botrytis cinerea. Recent understandingof the mechanisms of fungal antagonism at the molecularlevel is providing new tools to genetically improve the performanceof biocontrol agents. A number of antifungal compoundshave been identified and their specific role assessed by gene disruption.Further, a few promoters induced during mycoparasitismand biocontrol have been cloned and characterized, andthey can be used to express in an inducible manner foreign genesthat may augment biocontrol ability. For instance, we have expressedin T. atroviride a gene of Aspergillus nidulans encodingfor a glucose oxidase under a biocontrol-related promoter, andhave obtained mutants more powerful than the wild type both inpathogen biocontrol and induction of systemic disease resistancein the plant

PLANT GROWTH AND ISR PROMOTION BY TRICHODERMA HARZIANUM T22

Trichoderma harzianum T22, a fungal antagonist, is one of themost widely used active ingredients in commercial bio-fungicidesand bio-fertilizers. It has not only mycoparasitic activity, but canalso activate extensive metabolic changes in treated plants, resultingin a systemic resistance to a pathogen attack, thus indirectlyaltering plant-pathogen interactions. By analyzing the T.harzianum T22 “secretome” a few key “effectors” involved in Trichoderma-plant cross-talk were identified. One of these effectorssecreted was a class II hydrophobin HYTRA1. This protein wastested for its antimicrobial activity and its ability to induce a defenceresponse in tomato plants. In in vitro and in vivo assays,HYTRA1 directly inhibited pathogen development. In tomatoplants, depending upon the concentration, it induced a multiplicityof effects. HYTRA1 activated oxidative burst, the antioxidantsystem, and ISR with the accumulation of defence-related compoundsimportant in plant defence. Further physiological effectsincluded the induction of de novo rhizogenesis, and an epinasticphenotype in HYTRA1-transformed tomato. The involvement ofHYTRA1 in the T. harzianum molecular crosstalk with the plantwas confirmed when HYTRA1 disruptants proved unable to induceroot growth promotion and ISR in tomato