Strategic Project - LA 16 - 2013-2014

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Publications

Hydromonas duriensis gen. nov., sp. nov., isolated from freshwater

Publication . Vaz-Moreira, Ivone; Narciso-da-Rocha, Carlos; De Brandt, Evie; Vandamme, Peter; Ferreira, A. C. Silva; Lobo-da-Cunha, Alexandre; Nunes, Olga C.; Manaia, Célia M.

An aerobic, Gram-stain-negative rod, designated strain A2P5T , was isolated from the Douro river, in Porto, Portugal. Cells were catalase- and oxidase-positive. Growth occurred at15–30 8C, at pH 6–8 and in the presence of 1 % (w/v) NaCl. The major respiratory quinone was Q8, the genomic DNA had a G+C content of 47¡1 mol%, and phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol were amongst the major polar lipids. On the basis of 16S rRNA gene sequence analysis, strain A2P5T was observed to be a member of the family Burkholderiaceae, but could not be identified as a member of any validly named genus. The low levels of 16S rRNA gene sequence similarity to other recognized taxa (,91 %), together with the comparative analysis of phenotypic and chemotaxonomic characteristics, supported the proposal of a novel species of a new genus within the family Burkholderiaceae. The name Hydromonas duriensis gen. nov., sp. nov. is proposed. The type strain of Hydromonas duriensis is A2P5T (5LMG 28428T 5CCUG 66137T).

2015Journal article

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Effects of different edible coatings on polyphenol oxidase activity and colour of fresh-cut apple during cold storage

Publication . Bertrand, Charlotte; Raposo, Maria Filomena de Jesus; Morais, Rui Manuel Santos Costa de; Morais, Alcina Maria Miranda Bernado de

Fresh-cut fruits are highly susceptible to enzymatic browning. The aim of this study was to evaluate the effects of different coatings on polyphenol oxidase (PPO) activity and colour of ‘Royal Gala’ apple cubes during storage at 4°C. The main constituents (polysaccharides) of the coatings used were carrageenan, alginate, the exopolysaccharide (EPS) from the marine microalga Porphyridium cruentum, pectin, and carboxymethyl cellulose (CMC). When PPO activity increased, the apple cubes became browner (L* values decreased, and/or a* and/or b* values increased) for pectin, carrageenan, EPS 5 g.L–1 and CMC coatings. EPS coated apple cubes, in particular, did not present the best results in order to prevent the colour changes and to lower down PPO activity, but the results obtained were very similar to those of alginate. The coating based on pectin was the most recommended to preserve fresh-cut ‘Royal Gala’ apple closely followed by CMC.

2015Journal article

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Biosorption of fluoroquinolones by activated sludge and aerobic granules sludge

Publication . Ferreira, Vanessa R. A.; Amorim, Catarina L.; Cravo, Sara M.; Tiritan, Maria E.; Castro, Paula M. L.; Afonso, Carlos M. M.

Antibiotic residues have been detected in various environmental matrices, such as surface water and even drinking water. Although present at low levels (μg/L, ng/L), many antibiotics are bioaccumulative, pseudo-persistent and can promote resistance/alterations in bacterial populations [1]. Recent studies on antibiotics removal by activated sludge (AS) and aerobic granules (AGS) show biosorption as the dominant process, determining the fate of these micropollutants [2-3]. In this work the biosorption of three widely used fluoroquinolones (FQ) - ofloxacin (OFL), norfloxacin (NOR) and ciprofloxacin (CPF) - to AS and AGS was evaluated. A High Performance Liquid Chromatography with Fluorescence Detection (HPLC-FD) method was validated and used to follow the biosorption of the target FQ. Data obtained in this study contribute to a better comprehension of FQ biosorption behavior in AS and AGS. At pH 7 AS showed better performance to biosorb OFL, NOR and CPF than AGS. The higher biosortion capacity of AS was probably due to the negative charge on its surface, evaluated by a zeta potential of -25.65 mV, at pH 7. OFL was the less biosorbed, both onto AS and AGS, because this FQ at pH 7 is mainly present in its anionic form. The equilibrium data for AS showed a better fit to the Langmuir model, while the model that presented better fit for AGS was the Freundlich model. The FQ could be desorbed from AGS at pH 3, pH 8 and pH 9 whereas at pH 4 the biosorption process was promoted.

2015-05-13Conference object

Open access

Persistent and non-persistent strains of Listeria monocytogenes: A focus on growth kinetics under different temperature, salt, and pH conditions and their sensitivity to sanitizers

Publication . Magalhães, Rui; Ferreira, Vânia; Brandão, Teresa R. S.; Casquete Palencia, R.; Almeida, Gonçalo; Teixeira, Paula

This study aimed to investigate the effect of different conditions, including temperature (37 C, 22 C, and 4 C), NaCl concentrations (2.5%, 4%, and 8%), and acidity (pH ¼ 5), on the growth response of persistent and non-persistent isolates of Listeria monocytogenes. The resistance to two common sanitizers (benzalkonium chloride and hydrogen peroxide) was also investigated. A selected group of 41 persistent and non-persistent L. monocytogenes isolates recovered from three cheese processing plants during a previous longitudinal study was assembled. Average lag time was similar for persistent and non-persistent isolates grown at 37 C, 22 C and 4 C but significantly shorter (p < 0.05) for persistent isolates grown at 2.5%, 4% and 8% NaCl, and at pH 5. Average growth rates were significantly higher (p < 0.05) for persistent than for non-persistent isolates when grown at 22C, 2.5%, 4% and 8% NaCl, and at pH 5. These results suggest that persistent strains may be better adapted to grow under stressful conditions frequently encountered in food processing environments than non-persistent strains. No relation between persistence and resistance to the tested sanitizers was found.

2016Journal article

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Remoção de fluoroquinolonas do ambiente: biossorção a lamas ativadas e a grânulos aeróbios

Publication . Ferreira, Vanessa R. A.; Amorim, Catarina L.; Cravo, Sara M.; Tiritan, Maria E.; Castro, Paula M. L.; Afonso, Carlos M. M.

Diversas matrizes ambientais, particularmente águas residuais, têm revelado a presença de antibióticos. Embora presentes em níveis vestigiais (ng.L-1 a µg.L-1,), estes compostos são pseudo-persistentes e, naquelas concentrações, podem também promover resistências nas populações bacterianas [1]. Estudos recentes de remoção de antibióticos com lamas ativadas (AS) e grânulos aeróbios (AGS) mostram a biossorção como processo dominante e eficaz na remoção destes micropoluentes [2,3]. O presente trabalho explorou a biossorção de três fluoroquinolonas (FQ) - ofloxacina (OFL), norfloxacina (NOR) e ciprofloxacina (CPF) - a AS e AGS. Com vista a uma melhor compreensão dos fenómenos que ocorrem durante o processo, foram estudados diversos parâmetros que condicionam a biossorção. As AS demonstraram melhor desempenho na remoção da OFL, NOR e CPF relativamente aos AGS. No entanto, nas concentrações estudadas, não foi possível promover a remoção total dos fármacos. A capacidade mais elevada de biossorção das AS foi atribuída à carga negativa da superfície da biossorção, representada por um potencial zeta de -25,65 mV, a pH 7. A OFL foi a FQ menos removida, tanto pelas AS como pelos AGS, porque a OFL a pH 7 está principalmente presente na forma aniónica, com uma pequena percentagem, na forma zwiteriónica. Em AGS verifica-se um aumento da biossorção da OFL, NOR e CPF em pH ácido (pH 4) e maior dessorção em pH alcalino (pH 8 a 9). Observou-se também que ocorre a destruição da estrutura granular dos AGS quando o pH do meio é igual ou inferior a 3. Os resultados obtidos neste estudo contribuem para uma utilização mais eficaz de AS e AGS na remoção de antibióticos fluoroquinolonas do ambiente.

2014-11Conference object

Open access