Josefina Aleu

THE PUTATIVE ROLE OF BOTRYDIAL AND RELATED METABOLITES IN THE INFECTION MECHANISM OF Botrytis cinerea

Phytotoxic assays, performed both in vitro and in vivo on leaves of Phaseolus vulgaris, with metabolites excreted by the fungus B. cinerea are evaluated. Exogenous application of the phytotoxin botrydial has been found to produce severe chlorosis and cell collapse and facilitated fungal penetration and colonization of plant tissue. The results also show a light-dependent action mechanism for the phytotoxin and seem to indicate that botrydial is a non-host-specific toxin involved in fungal infection of B. cinerea.

Pollutants Biodegradation by Fungi

One of the major problems facing the industrialized world today is the contamination of soils, ground water, sediments, surfacewater and air with hazardous and toxic chemicals. The application of microorganisms which degrade or transform hazardous organic contaminants to less toxic compounds has become increasingly popular in recent years. This review, with approximately 300 references covering the period 2005-2008, describes the use of fungi as a method of bioremediation to clean up environmental pollutants.

Non-peptide metabolites from the genus Bacillus.

Bacillus species produce a number of non-peptide metabolites that display a broad spectrum of activity and structurally diverse bioactive chemical structures. Biosynthetic, biological, and structural studies of these metabolites isolated from Bacillus species are reviewed. This contribution also includes a detailed study of the activity of the metabolites described, especially their role in biological control mechanisms.

Overexpression of the trichodiene synthase gene tri5 increases trichodermin production and antimicrobial activity in Trichoderma brevicompactum

Trichoderma brevicompactum produces trichodermin, a simple trichothecene-type toxin that shares the first steps of the sesquiterpene biosynthetic pathway with other phytotoxic trichothecenes from Fusarium spp. Trichodiene synthase catalyses the conversion of farnesyl pyrophosphate to trichodiene and it is encoded by the tri5 gene that was cloned and analysed functionally by homologous overexpression in T. brevicompactum. tri5 expression was up-regulated in media with glucose, H(2)O(2) or glycerol. tri5 repression was observed in cultures supplemented with the antioxidants ferulic acid and tyrosol. Acetone extracts of tri5-overexpressing transformants displayed higher antifungal activity than those from the wild-type. Chromatographic and spectroscopic analyses revealed that tri5 overexpression led to an increased production of trichodermin and tyrosol. Agar diffusion assays with these two purified metabolites from the tri5-overexpressing transformant T. brevicompactum Tb41tri5 showed that only trichodermin had antifungal activity against Saccharomyces cerevisiae, Kluyveromyces marxianus, Candida albicans, Candida glabrata, Candida tropicalis and Aspergillus fumigatus, in most cases such activity being higher than that observed for amphotericin B and hygromycin. Our results point to the significant role of tri5 in the production of trichodermin and in the antifungal activity of T. brevicompactum.

Biotransformations by Botrytis species

Abstract Biotransformations by Botrytis sp. are reviewed. Various substrates and the Botrytis species used for the transformations are included in this review of the literature for the period 1961–1999.

Biotransformation of the fungistatic sesquiterpenoids patchoulol, ginsenol, cedrol and globulol by Botrytis cinerea

Abstract The antifungal activity of natural sesquiterpenoids patchoulol, ginsenol, cedrol and globulol against the fungus Botrytis cinerea has been determined. The diminishing of the effect after 3–6 days suggests that a mechanism of detoxification is present. Biotransformation of these fungistatic compounds has been investigated as a method of studying this mechanism.

Overexpression of the Trichoderma brevicompactum tri5 Gene: Effect on the Expression of the Trichodermin Biosynthetic Genes and on Tomato Seedlings

Trichoderma brevicompactum IBT 40841 produces trichodermin, a trichothecene-type toxin that shares most of the steps of its biosynthesis with harzianum A, another trichothecene produced by several Trichoderma species. The first specific step in the trichothecene biosynthesis is carried out by a terpene cylcase, trichodiene synthase, that catalyzes the conversion of farnesyl pyrophosphate to trichodiene and that is encoded by the tri5 gene. Overexpression of tri5 resulted in increased levels of trichodermin production, but also in an increase in tyrosol and hydroxytyrosol production, two antioxidant compounds that may play a regulatory role in trichothecene biosynthesis, and also in a higher expression of three trichothecene genes, tri4, tri6 and tri10, and of the erg1 gene, which participates in the synthesis of triterpenes. The effect of tri5 overexpression on tomato seedling disease response was also studied.

Some metabolites of Botrytis cinerea related to botcinolide

Four new botcinolide derivatives 4-O-methylbotcinolide, 3-O-acetyl-5-O-methylbotcinolide, 3-O-acetyl-2-epibotcinolide and 2-epibotcinolide have been isolated from the plant pathogen, Botrytis cinerea. Their structures have been established by extensive spectroscopic methods.

SYNTHESIS AND ANTIFUNGAL ACTIVITY OF ANALOGUES OF NATURALLY OCCURRING BOTRYDIAL PRECURSORS

Analog compounds of the proposed intermediates of the biogenetic pathway to botrydial have been synthesized. These compounds were tested for their potential antifungal activity against the phytopathogenBotrytis cinerea. Our results showed a fungistatic effect of some compounds on mycelium growth. The most significant effect was exerted by 2-α-hydroxy-2,3-dihydro-1-epiprobotrydial, which inhibited growth ofB. cinerea. Some aspects of structure-activity relationships are discussed.

Terpenoid biotransformations by Mucor species

Terpenoids are natural products of great interest due to their widespread use in agrochemicals, drugs, fragrances, flavouring and pigments. Biocatalysts are increasingly being used in the search for new derivatives with improved properties especially to obtain structurally novel leads for new drugs which are difficult to obtain using conventional organic chemical methods. This review, covering up to the end of 2012, reports on the application of Mucor species as catalysts in terpenoid biotransformation to obtain new drug targets, enhance pharmacological activity or decrease the unwanted effects of starting material.