Percorrer por autor "Nogueira, Liliana"
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- Entomopathogenic fungi associated with the main insect pest in the Northeast of Portugal: preliminary resultsPublication . Baptista, Paula; Pereira, Eric Carvalho; Nogueira, Liliana; Bento, Albino; Santiago-Álvarez, C.; Quesada-Moraga, Enrique; Pereira, J.A.Due to the problems caused by the use of chemical insecticides for humans and environment alternative pest control methods are an important topic of research. The use of microbial insecticides especially fungal agents are an attractive and promising alternative for biological control of insect pests. The aim of this work was to identify naturally occurring entomophatogenic fungi on the olive moth, Prays oleae Bern., in the northeast of Portugal, as first step to select biological control agent again this olive pest. The experimental work was carried out during 2007 in the three generation of the insect (phyllophagous, anthophagous and carpophagous generation). In each generation P. oleae larvae and pupae were collected in different groves and were put in glass vials in a climatic chamber with a photoperiod of 12h light:12h dark, 22ºC (light): 16ºC (dark) and 60% relative humidity, until emergency of the adults. From dead larvae, fungi were isolated on PDA plates and incubated at room temperature. Pure cultures were morphological and molecularly identified based on the ITS region of the rDNA. From the identified species Beauveria bassiana Vuill. and Cordyceps sinensis (Berk.) Sacc. were the most promising being B. bassiana the most abundant one.
- Influence of the C:N ratio and pH on ectomycorrhizal fungal growthPublication . Baptista, Paula; Nogueira, LilianaWild edible mushrooms are a natural resource with a high nutritional and economic value. Several studies have demonstrated that the commercially mushroom harvesting could be an important additional source of income in both developing and developed countries. The species most appreciate in the entire world are ectomycorrhizal (EM) and are usually the most valued. This aspect derived essentially from the difficulty to obtaining these symbiotic fungal species by culture. The main objective of the present study is to assess the influence of the C:N ratio and pH on the growth of three EM fungal species, under in vitro conditions. The species studied were Lactarius deliciosus Fr., Suillus bovinus L.:Fr. and Boletus edulis Bull.:Fr, all with high economic importance. The fungal were cultivated on solid modified Melin-Norkrans (MMN) medium with different C:N ratio (37.7, 75.5, 113.2) at pH 4, 5, 6 and 7, and fungi growth was determined over 63 days of culture. Morphological characteristics of each fungal culture were also assessed. The results obtained showed that both C:N ratio and pH had influence in fungal growth. The growth of B. edulis and L. deliciosus were significantly higher in medium with 113.2 C:N ratio when compared to other C:N ratios. By contrast, S. bovinus have the highest growth on medium with a C:N equal 75.5. The best pH value for S. bovinus, B. edulis and L. deliciosus growth was, respectively, 5, 6 and 4. No macroscopic nor microscopic alterations in mycelial morphological characteristics between isolates growth at different C:N ratio and pH were detected.
- The use of the ITS region in marketable mushrooms authenticityPublication . Nogueira, Liliana; Oliveira, Ivo; Baptista, PaulaEdible mushrooms, due to their flavour and nutritional characteristics, are very popular in many dishes. Some species are high valuated and reaching high market values. There are frequent reports of adulteration of these kinds of products due to the presence of fungal species less expensive among others with high-value market. This adulteration occurs especially in products in which the flavour is not prominent and in which the mushrooms are difficult to examine. In this work we utilized the internal transcribed spacer (ITS) for the identification of marketable mushrooms species in order to detected fraudulent addition of cheaper species. The products analysed were labelled as Agaricus bisporus (known as white mushroom), Portobello, Shiitake, Maitake, Enoki, Eringi, Auricularia auricula-judae, Cantharellus cibarius, Craterellus cornucopioides, shimeji and Boletus edulis. Following DNA isolation, the corresponding ITS regions were amplified and sequenced, using the universal primers ITS1FO and ITS4RE. The obtained DNA sequences were analysed and fungal identification was performed by comparison with deposited sequences on NCBI database. The results obtained shown that the ITS region is a suitable method of identifying mushroom species. Furthermore it was verified that the great number of the mushrooms analysed were correctly identified. However, one of the products, the shimeji, is uncorrected labelled. The advantages and disadvantages of the use of the ITS region to detect frauds in marketed mushrooms will be present and discussed.
- Volatile composition of three species of wild mushrooms from Trás-os-Montes region using HS-SPME and GC/IT-MSPublication . Nogueira, Liliana; Malheiro, Ricardo; Pinho, P. Guedes de; Baptista, PaulaTrás-os-Montes region is considered one of the richest regions of Portugal concerning the existence of wild mushrooms. In the present work, was studied the volatile profile of three species of wild mushrooms, Hebeloma crustuliniforme, Clitocybe odora and Tricholoma fracticum. These species have different flavours, namely radish-, anise-like odor, and not distinctive or slightly mealy odor, respectively. The volatile fractions were determined in fresh mushrooms by headspace solid-phase microextraction (HS-SPME) combined with gas-chromatography/ion trap-mass spectrometry (GC/IT-MS). Several volatile compounds were identified, belonging to different chemical classes. The three studied mushroom species reported different volatile profiles as presented in Figure 1. Meanwhile these species are mainly composed by alcohols and aldehydes, and in minor content by sesquiterpenes, terpenic compounds, esters, ketones and other chemical classes. 3-Octanol and 1-octanol were identified in the species contributing to their flavour. ρ-Anisaldehyde was only identified in Clitocybe odora and was the main volatile compound identified in this specie. It contributes with the characteristic anise smell of this mushroom, and could be also used as a chemical authenticity marker. Linalool was present in the three species in considerable amounts contributing with floral scents. Overall the volatile profile of the three species contributes with characteristic fragrances, which allow recognizing each one of them.