Centre for the Research and Technology of Agro-Environmental and Biological Sciences

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Publications

Aflatoxin Contamination of Various Staple Foods from Angola and Mozambique

Publication . Matusse, Cláudio; Lucamba, Zelda; Bila, João; Macuamule, Custódia; Sampaio, Ana; Afonso, Sandra; Venâncio, Armando; Rodrigues, Paula

Aflatoxins constitute a significant risk in staple foods produced in African countries. This research aimed to analyze the total aflatoxin (AFT) contamination of various staple foods in Angola and Mozambique. A total of 233 samples of corn, peanuts, beans, rice, and cassava flour collected from farmers or local markets from the province of Cuanza Sul, Angola, and the provinces of Gaza and Inhambane, South Mozambique, were analyzed for the presence of AFT using the lateral flow strip method via AgraStrip® ProWATEX® (Romer). The results showed that, from all matrices, the highest incidence and level of AFT were found in corn produced in Mozambique, with medians ranging from 6.5 to 66.5 μg/kg, with the samples showing values as high as 9200 μg/kg. Levels higher than the maximum admissible levels recommended by the Codex Alimentarius Commission for cereals and pulses (15 μg/kg) were observed in up to 90% of the corn samples, depending on the province. Corn produced in Angola showed lower amounts of AFT, with medians ranging from 1.2 to 7.7 μg/kg. Considering the maximum admissible levels for AFT recommended by the European Commission and the Codex Alimentarius Commission for cereals and pulses, the level of AFT contamination in staple food produced and consumed in the studied provinces is high and constitutes a public health risk for the population. Therefore, risk mitigation strategies are urgently needed.

2024Journal article

Open access

Multiresistant bacteria: invisible enemies of freshwater mussels

Publication . Saavedra, Maria José; Fernandes, Conceição; Teixeira, Amílcar; Álvarez, Xana; Varandas, Simone

Freshwater mussels are among the most endangered groups of fauna anywhere in world. The indiscriminate use of antibiotics has led to the emergence of resistant strains. These antibiotic-resistant bacteria play a key role in increasing the risk allied with the use of surface water and in spread of resistance genes. Two endangered freshwater mussel species, Margaritifera margaritifera and Potomida littoralis, were sampled at 4 sampling sites along a 50 km stretch of River Tua. Water samples were taken at same sites. Of the total of 135 isolates, 64.44% (39.26% from water and 25.19% from mussels) were coliform bacteria. Site T1, with the lowest concentration of coliform bacteria, and site T2 were the only ones where M. margaritifera was found. No E. coli isolates were found in this species and the pattern between water and mussels was similar. P. littoralis, which was present at T3/T4 sites, is the one that faces the highest concentration of bacterial toxins, which are found in treated wastewater effluents and around population centers. Sites T3/T4 have the isolates (water and mussels) with the highest resistance pattern, mainly to β-lactams. Water and P. littoralis isolates (T3/T4) showed resistance to penicillins and their combination with clavulanic acid, and to cephalosporins, precisely to a fourth generation of cephalosporin antibiotics. The analysis provides important information on the risk to water systems, as well as the need to investigate possible management measures. It is suggested that future studies on the health status of freshwater bivalves should incorporate measures to indicate bacteriological water quality.

2022Journal article

Open access

Desafios no ensino da ciência e tecnologia dos biofilmes

Publication . Simões, Manuel; Simões, Lúcia Chaves; Fernandes, Conceição

Os biofilmes são o resultado da tendência natural dos microrganismos se fixarem a superfícies (bióticas ou abióticas), multiplicarem e incorporarem numa matriz viscosa de substâncias poliméricas extracelulares (EPS). À medida que o biofilme se desenvolve, o descolamento e os processos de crescimento entram em equilíbrio, levando a uma quantidade constante de biomassa na superfície e à libertação de células do biofilme que permitem a colonização de superfícies vizinhas e a formação de novas comunidades sésseis. EPS dos biofilmes são responsáveis pela ligação entre as células e com outros materiais particulados. A adaptação bem sucedida das bactérias às mudanças das condições naturais requer também que o microrganismo possa sentir e responder ao seu ambiente externo e, em consequência, modular a expressão dos seus genes. Mesmo que os biofilmes sejam provavelmente a primeira forma de vida comunitária na Terra, a incorporação de aspetos científicos da ciência e tecnologia dos biofilmes nos conteúdos de ensino pré ou pós graduado é uma tarefa desafiante, uma vez que esta área de investigação está em constante evolução.

2021Book part

Open access

Effect of Foliar Application of Nitrogen-Fixing Microorganisms and Algae Extracts on Nutritional Status and Yield of Hazelnut and Walnut Trees

Publication . Arrobas, Margarida; Roque, João; Martins, Sandra; Brito, Cátia; Correia, Carlos M.; Rodrigues, Manuel Ângelo

This study presents the results of two on-farm trials evaluating the efficacy of a nitrogen (N)-fixing inoculant (Methylobacterium symbioticum) applied as a foliar spray to provide N to hazelnut (Corylus avellana L.) and walnut (Juglans regia L.) trees. In the hazelnut trial, a factorial design was employed with soil N application at three levels [0 (N0), 40 (N40), and 80 (N80) kg ha−1] and foliar application of the inoculant (Yes and No). The walnut trial was arranged as a completely randomized design with three treatments: the N-fixing microorganism, a seaweed extract, and a control. Soil N application significantly increased hazelnut yield in 2021 (1.99, 2.49, and 2.65 t ha−1 for N0, N40, and N80, respectively) but not in 2022 (average values ranging from 0.28 to 0.33 t ha−1). The inoculant application did not significantly affect hazelnut yield. In the walnut trial, no significant differences were observed among the treatments in either year. The average yields ranged from 1.72 to 2.38 t ha−1 in 2021 and 0.66 to 0.84 t ha−1 in 2022. Soil N application in hazelnuts tended to increase leaf N concentration and significantly increased kernel N concentration. The inoculant increased leaf N concentration in one of the three sampling dates but did not affect kernel N concentration. In walnuts, the inoculant did not increase leaf N concentration but significantly increased kernel N concentration in one of the two years. The seaweed extract did not influence walnut yield or leaf N concentration. None of the treatments in either trial consistently affected the concentration of other macronutrients and micronutrients in the leaves. Therefore, while the inoculant showed some potential to improve the N nutritional status of the trees, it did not affect the yield. Overall, the results of the inoculant application were not sufficiently compelling, indicating the need for further studies on these species before the commercial product can be confidently recommended to farmers.

2025Journal article

Open access