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Lebenslauf.

Elicitors of induced disease resistance in postharvest horticultural crops: a brief review

Increasing loss of conventional fungicides due to pathogen resistance and general unacceptability in terms of public and environmental risk have favoured the introduction of integrated pest management (IPM) programmes. Induction of natural disease resistance (NDR) in harvested horticultural crops using physical, biological and/or chemical elicitors has received increasing attention over recent years, it being considered a preferred strategy for disease management. This article reviews the enhancement of constitutive and inducible antifungal compounds and suppression of postharvest diseases through using elicitors. The effect of timing of pre- and/or postharvest elicitor treatment and environment on the degree of elicitation and the potential for inducing local acquired resistance, systemic acquired resistance and/or induced systemic resistance to reduce postharvest disease is discussed. The review highlights that more applied and basic research is required to understand the role that induced NDR can play in achieving practical suppression of postharvest diseases as part of an IPM approach. (C) 2003 Elsevier B.V. All rights reserved.

Aspergillazines A-E: novel heterocyclic dipeptides from an Australian strain of Aspergillus unilateralis

Biological and chemical pro ling of an Australian strain of the fungus Aspergillus unilateralis (MST-F8675), isolated from a soil sample collected near Mount Isa, Queensland, revealed a complex array of metabolites displaying broad chemotherapeutic properties. Noteworthy among these metabolites were a unique series of highly modified dipeptides aspergillazines A-E, incorporating a selection of unprecedented and yet biosynthetically related heterocyclic systems. Co-occurring with the aspergillazines was the recently described marine-derived fungal metabolite trichodermamide A (cf. penicillazine), whereas re-fermentation of A. unilateralis in NaCl (1%) enriched media resulted in co-production of the only other known example of this structure class, the marine-derived fungal metabolite trichodermamide B. Further investigation of A. unilateralis returned the known terrestrial fungal metabolite viridicatumtoxin as the cytotoxic and antibacterial principle, together with E-2-decenedioic acid, ferulic acid, (7E,7'E)-5,5'-diferulic acid and (7E,7'E)-8,5'-diferulic acid. The aromatic diacids have previously been reported from the chemical and enzymatic (esterase) treatment of plant cell wall material, with their isolation from A. unilateralis being their first apparent reported occurrence as natural products. Structures for all metabolites were determined by detailed spectroscopic analysis and, where appropriate, comparison to literature data and/or authentic samples.

Roquefortine E, a diketopiperazine from an Australian isolate of Gymnoascus reessii

The new isoprenylated diketopiperazine roquefortine E (6) has been isolated from an Australian soil isolate of the ascomycete Gymnoascus reessii. The known fungal metabolite roquefortine C (1) was also recovered as the major antibacterial principle, and all structures were assigned by detailed spectroscopic analysis.

Citrinin revisited: from monomers to dimers and beyond

Detailed chemical analysis of the solid phase fermentation of an Australian Penicillium citrinum isolate has returned the known compounds citrinin (1), phenol A acid (6), dihydrocitrinone (7) and dihydrocitrinin (8), together with a novel cytotoxic dimer, dicitrinin A (5). Dicitrinin A (5) was determined to be a dimerised artefact of the major co-metabolite citrinin, and its structure solved by spectroscopic analysis and chemical modi. cation. Analysis of the products encountered during the controlled decomposition of citrinin led to the discovery of additional citrinin dimers and delineated a plausible mechanistic pathway linking all monomeric and dimeric citrinin degradation products.

Quinolactacins revisited: from lactams to imide and beyond

Chemical analysis of a solid phase fermentation of an Australian Penicillium citrinum strain has returned all known examples of a rare class of N-methyl quinolone lactams, quinolactacins A2 (1), B2 (2), C2 (3) and Al (4), together with the new quinolactacins B1 (5), C1 (6), D1 (7) and D2 (8), and the novel derivatives quinolonimide (9) and quinolonic acid (10). Complete stereostructures were assigned to all these compounds by detailed spectroscopic analysis and chemical interconversion. Carefully controlled and monitored decomposition studies have confirmed that quinolactacins readily undergo C-3 epimerization and oxidation, and under appropriate conditions convert to quinolonimide and quinolonic acid. Mechanisms for key transformations are proposed. The decomposition studies suggested that only quinolactacins A2 (1) and B2 (2) are genuine natural products, with all other isolated compounds being decomposition artefacts. Quinolactacins C1 (6), C2 (3), and the racemic mixture of quinolactacins D1/D2 (8/7) all displayed notable cytotoxic activity.

Mycotoxins and abnormal embryonic development

This chapter reviews studies on the effects of mycotoxins on embryonic and fetal development, especially those toxins that are global food and feed contaminants. The toxins discussed include aflatoxin produced by Aspergillus flavus and A. parasiticus, ochratoxin which is produced by Aspergillus species particularly A. ochraceus as well as Penicillium verrucosum, ergot alkaloids produced by Claviceps spp., and the Fusarium toxins (fumonisins, deoxynivalenol [vomitoxin], and zearalenone). These toxins have been shown to be teratogenic and/or embryotoxic in different animal bioassays. The implications of toxicity on embryogenesis, and the progress of research on these mycotoxins, are also examined.

Inhibition of microbial colonization of shipboard fuel systems

The aim of the investigation was to study the problem of colonization of shipboard fuel systems and to examine the effect of a number of environmental factors on microbial growth and survival in order to find potential preservative treatments. A variety of microbial species were isolated from samples taken from fuel storage tanks. Bacteria were more numerous than yeasts or fungi and most microorganisms were found at the fuel/water interface. 1he salinity, pH and phosphate concentration of some water bottoms were characteristic of sea water. Others were brackish, acidic and varied in phosphate content. Microorganisms were cultured under a number of environmental conditions. After prolonged incubation, the inoculum size had no effect on the final biomass of Cladosporium resinae but the time required to achieve the final mass decreased with increasing spore number. Undecane supported better growth of the fungus than diesel fuel and of four types of diesel fuel, two allowed more profuse growth. With sea water as the aqueous phase, a number of isolates were inhibited but the addition of nutrients allowed the development of many of the organisms. Agitation increased the growth of C. resinae on glucose but inhibited it on hydrocarbons. The optimum temperature fgr growth of C. resinae on surface culture lay between 25º C and 30º C and growth was evident at 5º C but not at 45º C. In aqueous suspension, 90% of spores were inactivated in around 60 hours at 45ºC and the same proportion of spores of C. resinae and Penicillium corylophilum were destroyed after about 30 seconds at 65ºC. The majority of bacteria and all yeasts in a water bottom sample were killed within 10 seconds at this temperature. An increase in the concentration of an organo-boron compound caused more rapid inactivation of C. resinae spores and raising the temperature from 25ºC to 45°C significantly enhanced the potency of the biocide.

The effects of substrate water availability on the isolation and growth of fungi

The work reported in this thesis was carried out to contribute to the knowledge of the effects of substrate water availability or water activity (a ) on fungal growth parameters and its implications in the preparationw of materials susceptible to biodeterioration. Fungi were isolated from soils of different ecological sites at a range of substrate aw levels controlled by sodium chloride (NaCl). Three groups of fungi were isolated : firstly, those isolated only at high a (aw about 0.997).secondly, those isolated at high and decreasing aw (aw 0.997 to 0.85) and finally, those isolated at only decreased aw (aw O.95 to 0.80). From these isolations, test fungi were selected to study the effects of pH, temperature, exo-enzyme production and biocide efficacy at decreased aw levels, with glycerol and NaCl as a controlling solutes. The linear extension rates of the fungi increased at all test pH values near optimum a of growth. Test fungi of the Aspergillus glaucus group were found to be most resistant to low aw. Growth and survival of vegetative and fruiting bodies at elevated temperatures were enhanced with the addition of a controlling solutes. A. flavus, A. fumigatus displayed high heat resistance and A. amstelodami, A. versicolor and Penicillium citrinum displayed low heat resistance at high aw levels and vice versa at low aw levels. Amylase, lipase and protease activities were studied at lowered aw , using modifications of the test tube method of Raute11a and Cowling. Amylase and protease production in most xerophilic fungi ceased around 0.80 aw , but lipase production in some xerophilic fungi, including A. glatlcus fungi, was up to and including 0.70 aw with g1ycero1.

Alterações fisiológicas causadas por fungicidas em soja infectada naturalmente por oídio

Soybean crop is substantially important for both Brazilian and international markets. A relevant disease that affects soybeans is powdery mildew, caused by fungus Erysiphe diffusa. The objective of this master’s thesis was to analyze physiological changes produced by fungicides in two greenhouse-grown soybean genotypes (i.e., Anta 8500 RR and BRS Santa Cruz RR) naturally infected with powdery mildew. A complete randomized block design was used with six replications in a 2x5 factorial arrangement. Treatments consisted of applications of Azoxystrobin, Biofac (fermented solution of Penicillium sp.), Carbendazim or Picoxystrobin fungicides, and a Control (no fungicide application). Three applications were performed in the experimental period, and each eventually represented a period of data collection. Gas exchanges, chlorophyll content, fluorescence of chlorophyll a and disease severity were measured twice a week. Dry grain mass production was measured at the end of the experiment. Areas under progression curve of variables were submitted to both ANOVA and Tukey’s test at 5% significance. Treatments Azoxystrobin, Biofac and Picoxystrobin had higher photosynthetic rates than Control in the second period, with genotype Anta having higher rate than Santa Cruz. Biofac had higher transpiration rate than Control in the second period, while Biofac and Picoxystrobin had higher figures in Santa Cruz in the third period. Carbendazim had greater stomatal conductance in Anta, whilst Azoxystrobin, Biofac and Picoxystrobin had greater values than Carbendazim in Santa Cruz. Biofac and Picoxystrobin had greater intercellular CO2 concentration in Santa Cruz. Azoxystrobin and Picoxystrobin had greater instantaneous water use efficiency than Control, with Anta being more efficient than Santa Cruz. Biofac and Picoxystrobin had greater intrinsic water use efficiency in Anta, while Carbendazim increased efficiency in Santa Cruz. Azoxystrobin, Biofac and Picoxystrobin had greater carboxylation efficiency than Control in the second period, with Anta being more efficient than Santa Cruz. Azoxystrobin and Biofac had greater contents of chlorophylls a, b and a+b than Control in the second period. Azoxystrobin had greater effective quantum yield than Control and Picoxystrobin. All treatments faced increasing disease severity over time, with Anta being less resistant than Santa Cruz. As for production, data showed that: (1) Santa Cruz was more productive than Anta, having the greatest dry grain mass with Carbendazim, and (2) Anta’s lower disease severity did not translate into higher productions. In conclusion, strobilurins (Azoxystrobin and Picoxystrobin) and Biofac performed similarly as to their physiological effects on soybeans; however, these effects did not lead to increased dry grain mass by the end of the experiment.

Effet de la réduction et de la substitution du NaCl dans le Camembert sur la croissance de la microflore fongique d'affinage

Santé Canada encourage les transformateurs à réduire le contenu en NaCl dans plusieurs aliments, dont les fromages, puisque sa surconsommation est associée à plusieurs problèmes de santé. L’effet causé par la réduction du NaCl dans le Camembert, ou de sa substitution partielle par du KCl, sur la qualité globale de ce fromage n’est pas connu. Le but du projet visait à étudier la cinétique d’incorporation du sodium et du potassium lors du saumurage d’un Camembert commercial afin de produire des fromages réduits en NaCl et substitués par du KCl. Ces nouvelles conditions ont ensuite permis d’étudier le comportement des ferments fongiques d’affinage Penicillium camemberti et Geotrichum candidum. Les résultats ont démontré une modification du profil de croissance des deux espèces, plus accentuée chez G. candidum, en fonction des modifications salines apportées. L’impact causé par ces changements de comportement doit maintenant être évalué au niveau de l’activité spécifique des deux espèces.

Fungal contamination of sandpits from recreational parks and schools: a potential risk for human health

Sandpits used by children are frequently visited by wild life which constitutes a source of fungal pathogens and allergenic fungi. This study aimed to take an unannounced snapshot of the urban levels of fungal contaminants in sands, using for this purpose two public recreational parks, three elementary schools and two kindergartens. All samples were from Lisbon and neighboring municipalities and were tested for fungi of clinical interest. Potentially pathogenic fungi were isolated from all samples besides one. Fusarium dimerum (32.4%) was found to be the dominant species in one park and Chrysonilia spp. in the other (46.6%). Fourteen different species and genera were detected and no dermatophytes were found. Of a total of 14 species and genera, the fungi most isolated from the samples of the elementary schools were Penicillium spp. (74%), Cladophialophora spp. (38%) and Cladosporium spp. (90%). Five dominant species and genera were isolated from the kindergartens. Penicillium spp. was the only genus isolated in one, though with remarkably high counts (32500 colony forming units per gram). In the other kindergarten Penicillium spp. were also the most abundant species, occupying 69% of all the fungi found. All of the samples exceeded the Maximum Recommended Value (MRV) for beach sand defined by Brandão et al. 2011, which are currently the only quantitative guidelines available for the same matrix. The fungi found confirm the potential risk of exposure of children to keratinophilic fungi and demonstrates that regular cleaning or replacing of sand needs to be implemented in order to minimize contamination.

Occupational exposure to fungi and particles in animal feed industry

Background: Very few studies regarding fungal and particulate matter (PM) exposure in feed industry have been reported, although such contaminants are likely to be a significant contributing factor to several symptoms reported among workers. The purpose of this study has been to characterize fungal and dust exposure in one Portuguese feed industry. Material and Methods: Air and surface samples were collected and subject to further macro- and microscopic observations. In addition we collected other air samples in order to perform real-time quantitative polymerase chain reaction (PCR) amplification of genes from Aspergillus fumigatus and Aspergillus flavus complexes as well as Stachybotrys chartarum. Additionally, two exposure metrics were considered – particle mass concentration (PMC), measured in 5 different sizes (PM0.5, PM1, PM2.5, PM5, PM10), and particle number concentration (PNC) based on results given in 6 different sizes in terms of diameter (0.3 μm, 0.5 μm, 1 μm, 2.5 μm, 5 μm and 10 μm). Results: Species from the Aspergillus fumigatus complex were the most abundant in air (46.6%) and in surfaces, Penicillium genus was the most frequently found (32%). The only DNA was detected from A. fumigatus complex. The most prevalent in dust samples were smaller particles which may reach deep into the respiratory system and trigger not only local effects but also the systemic ones. Conclusions: Future research work must be developed aiming at assessing the real health effects of these co-exposures.

Fungi distribution in poultry feed

Feed can easily be contaminated and colonized by fungi that use up the nutrients for their own metabolism and growth, producing secondary metabolites such as mycotoxins that are not eliminated throughout the feed processing. The major problems associated with mycotoxin contaminated animal feed are metabolic disturbances resulting in poor animal productivity. In addition, handling contaminated animal feed can also raise health issues regarding workers exposure to fungi and mycotoxins. The scope of this work was to characterize fungal distribution in 11 poultry feed samples. Twenty grams of feed were suspended in 180 mL of distilled water and homogenized during 20 minutes at 200 rpm. The washed supernatant was plated in malt extract agar (MEA) and dichloran glycerol agar base (DG18) media for morphological identification of the mycobiota present. Using macro- and microscopic analysis of the colonies, fungal contamination was evident in 72.7% of the analyzed poultry feed samples. Fungal load ranged from 0 to 13140 CFU/g, and the most prevalent species/genera were F. graminearum complex (71.1%), Penicillium sp. (11.6%), Cladosporium sp. (8.8%), and Fusarium poae (3.6%). In addition to these species, we also isolated Aspergillus sections Circumdati, Nigri and Aspergilli, and Mucor and Rhizopus genus albeit at a lower abundance. The data obtained showed that, besides high fungal contamination, mycotoxins contamination is probably a reality, particularly in the final product since mycotoxins resist to all the processing operations including thermal treatment. Additionally, data claimed attention for the probable co-exposure to fungi and mycotoxins of the workers in feed industries.

Microbiota assessment in optical shops: an ignored concern to public health

The presence of microorganisms in ophthalmic instruments and surfaces can lead to the exposure of patients to several infections. However, there is no information regarding fungal and bacteria contamination in optical shops. This study aims to characterize fungi and bacteria contamination in air and surfaces from 10 optical shops covering also ophthalmic instruments. Air samples were collected through an impaction method onto malt extract agar (MEA) supplemented with chloramphenicol (0.05%) used for fungi and Tryptic Soy Agar (TSA) supplemented with nystatin (0.2%) used for bacteria. Outdoor samples were also performed to be used as reference. Surface and equipment’s swab samples were also collected side-by-side. All the collected samples were incubated at 27ºC for 5 to 7 days (fungi) or at 30º for 7 days (bacteria). Regarding fungal distribution, thirteen different species/genera were found in the air, being the most common Alternaria sp. (62.0%). Eight different species/genera were identified in the surfaces, ranging from 2 to 5x104 CFU/m2, being the most common A. versicolor complex and Penicillium sp. (40.0%). The trial frames were the most contaminated equipment, since 50.0% of the collected samples were with countless colonies. The airborne bacterial population indicated higher concentrations in the contactology office (average: 133 CFU/m3) than in the client’s waiting rooms (average: 126 CFU/m3). The surface samples indicated bacterial concentrations ranging from 2x104 to 1x106 CFU/m2, pointing out the automatic refractometer as the surface with higher bacterial load.