Browsing by Author "Lima, Nelson"
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- Aflatoxigenic fungi and aflatoxins in Portuguese almondsPublication . Rodrigues, Paula; Venâncio, Armando; Lima, NelsonAflatoxin contamination of nuts is an increasing concern to the consumer’s health. Portugal is a big producer of almonds, but there is no scientific knowledge on the safety of those nuts, in terms of mycotoxins. The aim of this work was to study the incidence of aflatoxigenic fungi and aflatoxin contamination of 21 samples of Portuguese almonds, and its evolution throughout the various stages of production. All fungi belonging to Aspergillus section Flavi were identified and tested for their aflatoxigenic ability. Almond samples were tested for aflatoxin contamination by HPLC-fluorescence. In total, 352 fungi belonging to Aspergillus section Flavi were isolated from Portuguese almonds: 127 were identified as A. flavus (of which 28% produced aflatoxins B), 196 as typical or atypical A. parasiticus (all producing aflatoxins B and G), and 29 as A. tamarii (all non-aflatoxigenic). Aflatoxins were detected in only one sample at 4.97 µg/kg.
- Biodegradation of bioaccessible textile azo dyes By Phanerochaete chrysosporiumPublication . Martins, Maria Adosinda; Ferreira, Isabel C.F.R.; Santos, Isabel C.; Queiroz, Maria João R.P.; Lima, Nelson
- Biodegradation of textile Azo Dyes by Phanerochaete chrysosporiumPublication . Ferreira, Isabel C.F.R.; Santos, Isabel C.; Queiroz, Maria João R.P.; Lima, NelsonAzo dyes are used extensively in the textile and dyestuff industries and effluents from these industrial processes are usually resistant to biological treatment. Textile azo dyes with bioaccessible groups such as guaiacol and 2,6-dimethoxyphenol, for lignin-degrading fungus as P. chrysosporium were synthesised.
- Calmodulin gene as good voucher as MALDI-TOF ICMS to identify Portuguese isolates of Aspergillus section FlaviPublication . Rodrigues, Paula; Santos, Cledir; Venâncio, Armando; Lima, NelsonAspergillus is a large genus, with a complex and ever evolving taxonomy. Section Flavi is one of the most significant Sections in the Genus. Taxonomy and species identification is subject of great interest for scientists aiming to clarify the species concept and limits within the section. Furthermore, this Section comprises both toxigenic and non-toxigenic species/strains, with great interest to biotechnology and food industry. Various genes, namely the rRNA (internal transcribed spacer (ITS) and partial LSU-rRNA regions), calmodulin and ~-tubulin genes, have been widely reported as good markers for Aspergillus species identification, because they are rapid and cost-effective.
- Characterisation of mycoflora and aflatoxigenic fungi from portuguese almonds: from production to commercializationPublication . Rodrigues, Paula; Venâncio, Armando; Lima, NelsonAflatoxins are among the most carcinogenic natural compounds known, and have been frequently detected in numerous agricultural commodities, nut fruits being among the most contaminated ones. These toxins are a result of the secondary metabolism of fungi belonging to the genus Aspergillus Section Flavi, namelly Aspergillus flavus, A. parasiticus and A. nomius. The early detection of aflatoxigenic fungal contamination and the preventive control of aflatoxin production seems to be the only viable way to respond to the rigorous limits imposed by EU legislation. In Portugal, knowledge on mycoflora and mycotoxigenic profiles of almonds is scarce. Our objective was to characterise portuguese almonds in respect to mycoflora, with strong emphasis on aflatoxigenic fungi, from production to commercialization. Various samples of almonds were collected from the field, as well as during storage and processing. Environmental data have also been recorded. Samples were plated directly on MEA+10% NaCl and all fungi belonging to the genus Aspergillus isolated and identified to the group or species level. All Aspergillus belonging to Section Flavi were further characterised based on their mycotoxigenic profile, with the aim of identifying aflatoxigenic and non-aflatoxigenic strains. Fungal diversity and relative frequencies of Aspergillus spp. were determined for the various samples and correlated with environmental conditions. We have observed a progressive reduction on fungal diversity of almonds from the field to the end of processing, as well as an increase of the frequency of more xerophilic fungi, including Aspergillus Section Flavi. Concerning the latter, we report that Aspergillus parasiticus are predominantly aflatoxigenic and Aspergillus flavus are predominantly non-aflatoxigenic. Other less common species have also been identified.
- Characterisation of mycoflora and aflatoxigenic fungi from portuguese almonds: from production to commercializationPublication . Rodrigues, Paula; Venâncio, Armando; Lima, NelsonAflatoxins are among the most carcinogenic natural compounds known, and have been frequently detected in numerous agricultural commodities, nut fruits being among the most contaminated ones. These toxins are a result of the secondary metabolism of fungi belonging to the genus Aspergillus Section Flavi, namelly Aspergillus flavus, A. parasiticus and A. nomius. The early detection of aflatoxigenic fungal contamination and the preventive control of aflatoxin production seems to be the only viable way to respond to the rigorous limits imposed by EU legislation. In Portugal, knowledge on mycoflora and mycotoxigenic profiles of almonds is scarce. Our objective was to characterise portuguese almonds in respect to mycoflora, with strong emphasis on aflatoxigenic fungi, from production to commercialization. Various samples of almonds were collected from the field, as well as during storage and processing. Environmental data have also been recorded. Samples were plated directly on MEA+10% NaCl and all fungi belonging to the genus Aspergillus isolated and identified to the group or species level. All Aspergillus belonging to Section Flavi were further characterised based on their mycotoxigenic profile, with the aim of identifying aflatoxigenic and non-aflatoxigenic strains. Fungal diversity and relative frequencies of Aspergillus spp. were determined for the various samples and correlated with environmental conditions. We have observed a progressive reduction on fungal diversity of almonds from the field to the end of processing, as well as an increase of the frequency of more xerophilic fungi, including Aspergillus Section Flavi. Concerning the latter, we report that Aspergillus parasiticus are predominantly aflatoxigenic and Aspergillus flavus are predominantly non-aflatoxigenic. Other less common species have also been identified.
- Characterization and differentiation of aflatoxigenic species of Aspergillus section Flavi by MALDI-TOF MSPublication . Rodrigues, Paula; Kallow, Wibke; Erhard, Marcel; Welker, Martin; Kozakiewicz, Zofia; Lima, Nelson; Venâncio, ArmandoAspergillus is a large genus, with a complex taxonomy. The genus is easily identifiedd by its characteristic conidiophore, but species identification and differentiation is complex, mainly because it is traditionally based on a range of morphological features. Aspergillus subgenus Circumdati section Flavi, also refered to as the A.dflavus group, has attracted worldwide attention for its industrial use and toxigenic potential. Sectiond Flavi is divided in two groups of species. One includes the aflatoxigenic species A. flavus, A. parasiticus and A. nomius, which cause serious problems in agricultural commodities, and the other one includes the non-aflatoxigenic species A. oryzae, A. sojae and A.dtamarii, traditionally used for production of fermented foods. Species from A. flavus group are morphologically and genetically very similar, and are therefore difficult to differentiate by both cultural and molecular methods. Matrix Assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF) Massd Spectrometry has already shown high potentialities in discriminating very closely related taxa. This work intended to discriminate 30 strains, which were previously classifieddas A. flavus group by morphological methods, using MALDI-TOF MS. These results are compared with those previously obtained by conventional methods.
- Characterization and identification of aspergillus section flavi isolates from portuguese almonds using a polyphasic approach including MALDI-TOF ICMSPublication . Rodrigues, Paula; Santos, Cledir; Venâncio, Armando; Lima, NelsonAspergillus is a large genus, with a complex and ever evolving taxonomy. Section Flavi is one of the most significant sections in the genus, and is one of the best studied among fungi, for the numerous industrial applications as well as for food safety issues. Section Flavi is composed of a large number of very closely related species. While these species are difficult to differentiate morphologically and even genetically, they differ in a characteristic that is of paramount importance for food safety, as some are responsible for the production of the highly toxigenic aflatoxins. Taxonomy and species identification are therefore subject of great interest for scientists aiming to clarify the species concept and limits within the section. In this sense, the establishment of schemes for species and for aflatoxigenic strains identification that are simultaneously accurate, sensitive, robust and expedite is mandatory. At present, reliable identification schemes typically imply the analysis of a wide variety of morphological, biochemical and molecular traits. Recently, Matrix-Assisted Laser Desorption/Ionisation Time-Of-Flight Intact Cell Mass Spectrometry (MALDI-TOF ICMS) has been used to generate spectra of protein masses in a range of 2,000 to 20,000 Da, which result in a taxa specific fingerprint. This technique has already shown high potentialities to discriminate very closely related taxa, but has rarely been used in fungal species identification, either on its one or as part of a polyphasic scheme of identification. This work aimed to: i) characterize the population of Aspergillus section Flavi collected from Portuguese almonds in relation to their aflatoxigenic potential; ii) identify the isolates by applying a set of morphological, biochemical, molecular and spectral analyses (polyphasic approach); iii) compare the data obtained from the various approaches in terms of sensitivity, reliability and user-friendliness; and iii) determine the validity of MALDI-TOF technique for the identification of closely related field isolates of section Flavi.
- Characterization of Aspergillus flavus isolated from winemaking grapesPublication . Soares, C.; Rodrigues, Paula; Kozakiewicz, Zofia; Lima, Nelson; Venâncio, ArmandoConcern about filamentous fungi in vineyards has been traditionally linked to the spoilage of grapes. However, the recent detection of ochratoxin A in wines has increased the interest in mycotoxins. Although not very common in grapes, Aspergillus flavus is occasionally isolated from grapes. A. flavus is the main producer of the well known carcinogenic mycotoxins, the aflatoxins, and the presence of this fungus and aflatoxins is of major food safety concern. The identification of A. flavus is not straightforward due mainly to similarities with its closely related species (A. parasiticus, A. nomius). Various morphological and biochemical parameters may be used for identification: Color of colonies on Czapek Medium (CZ), seriation of conidial heads, conidia ornamentation, production of aflatoxins B1, B2, G1 and G2, and production of cyclopiazonic acid.
- Children's conceptions about microorganisms and healthPublication . Carvalho, Graça S. de; Mafra, Paulo; Lima, NelsonChildren’s alternative conceptions on microorganisms and health are little studied in the literature. Several international studies have shown that these conceptions are incomplete, divergent from scientific knowledge and resistant to change, often even after formal education. This study aimed to identify children’s conceptions about microorganisms and health before the formal education of this content (5th grade) and two years after (7th grade). A questionnaire consisting of closed questions was applied to 439 pupils. Most pupils associate microorganisms with the disease and recognize the reason they should be vaccinated. Contrary to results in other studies, pupils associate vaccines with disease prevention rather than disease cure. Some children do not directly associate behaviours related to their hygiene and the need to disinfect wounds with the elimination of undesirable microorganisms. Also the beneficial aspects of the microorganisms are little recognized by the pupils. Statistical analysis showed significant differences (p <0.05) between the two groups in some answers. It is necessary to improve the approach to microorganisms right away in primary school. Textbooks and teachers should give more emphasis on the justification of personal hygiene and the beneficial aspects of microorganisms.