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- New insights on mechanisms of sulfonamide bio-transformation by environmental bacteriaPublication . Reis, Patrícia J.M.; Homem, Vera; Alves, Arminda; Vilar, Vítor J.P.; Manaia, Célia M.; Nunes, Olga C.
- Biodegradation of sulfamethoxazole and other sulfonamides by Achromobacter denitrificans PR1Publication . Reis, Patrícia J. M.; Reis, Ana C.; Ricken, Benjamin; Kolvenbach, Boris A.; Manaia, Célia M.; Corvini, Philippe F.X.; Nunes, Olga C.This study aimed to isolate and characterize a microbial culture able to degrade sulfonamides. Sul-famethoxazole (SMX)-degrading microorganisms were enriched from activated sludge and wastewater.The resultant mixed culture was composed of four bacterial strains, out of which only Achromobacterdenitrificans PR1 could degrade SMX. This sulfonamide was used as sole source of carbon, nitrogen andenergy with stoichiometric accumulation of 3-amino-5-methylisoxazole. Strain PR1 was able to removeSMX at a rate of 73.6 ± 9.6 molSMX/gcell dry weighth. This rate more than doubled when a supplement ofamino acids or the other members of the mixed culture were added. Besides SMX, strain PR1 was able todegrade other sulfonamides with anti-microbial activity. Other environmental Achromobacter spp. couldnot degrade SMX, suggesting that this property is not broadly distributed in members of this genus.Further studies are needed to shed additional light on the genetics and enzymology of this process.
- Use of image analysis on cheese sections for microstructural characterizationPublication . Reis, Patrícia J. M.; Malcata, F. Xavier
- Produção por tecnologias optimizadas de lacticínios tradicionais certificados: PROLACTISPublication . Reis, Patrícia M.; Domingos, Tiago D.; Freitas, A. Cristina; Macedo, Ângela C.; Trigueiros, José J. B. L.; Malcata, F. Xavier
- Enrichment and isolation of a bacterial strain able to degrade sulfamethoxazolePublication . Reis, P. J. M.; Reis, Ana C.; Manaia, C. M.; Corvini, Philippe F.X.; Nunes, Olga C.
- Alternative cheesemaking methods with raw ewes’ milk – microbiological, chemical, textural and sensory characteristicsPublication . Reis, Patrícia J. M.; Tavaria, Freni K.; Malcata, F. XavierSerra da Estrela cheese was manufactured using a novel, customised apparatus – designed to meet the specialty cheese’s specifications, and the resulting product was compared with that obtained via traditional manufacture in the same dairy. Semiindustrial cheesemaking led to a significantly (p<0.05) higher fat content in the final cheeses, with favourable consequences in terms of flavour and consumer acceptability – and significantly (p<0.05) lower viable numbers of (unwanted) enterococci in the matured cheese. Textural characteristics were broadly similar. Proteolysis was significantly (p<0.05) faster, but it was more variable in artisanal than in semi-industrial cheeses. The latter received significantly (p<0.05) better scores for texture, but lower scores for flavour. However, both products were within the specifications set forth by national regulations pertaining to Serra da Estrela PDO cheeses, so the novel apparatus is rather promising towards improved small-scale cheesemaking.
- Effect of dairy farm and milk refrigeration on microbiological and microstructural characteristics of matured Serra da Estrela cheesePublication . Tavaria, Freni K.; Reis, Patrícia J.M.; Malcata, F. XavierThis work was aimed at enumerating the viable microorganisms in ripened Serra da Estrela cheeses, manufactured from both refrigerated and non-refrigerated milk, in various dairies located throughout the demarcated region. Scanning electron microscopy was used to analyze the microstructure, and thus aid in understanding possible differences in their microbiological profile. The cheeses were allowed to ripen under controlled conditions, and sampled at 60, 90, 120, 150 and 180 d following manufacture. Viable numbers of lactic acid bacteria, staphylococci, Enterobacteriaceae and yeasts were obtained following standard plate counting on a number of selective media. Lactococcus was the most abundant genus (above 108 cfu g 1 of cheese) up to 120 d of ripening. No significant microstructural differences were observed in cheeses manufactured in different dairies over the ripening process. However, microstructural differences were apparent between cheeses manufactured with refrigerated versus non-refrigerated milk. r 2005 Elsevier Ltd. All rights reserved.
- Microstructural characterization of Serra cheese using low-vacuum SEMPublication . Reis, Patrícia J. M.; Malcata, F. Xavier
- Insights on sulfamethoxazole bio-transformation by environmental proteobacteria isolatesPublication . Reis, Patrícia J. M.; Homem, Vera; Alves, Arminda; Vilar, Vítor J.P.; Manaia, Celia M.; Nunes, Olga C.Although sulfonamide residues are frequently reported as freshwaters contaminants, information on the ability of native bacteria to modify these synthetic antibiotics is scarce. Our purpose was to investigate the potential of bacteria from different aquatic environments to cleave or transform sulfamethoxazole (SMX) and infer on their ability to reduce the toxicity of this antibiotic. From a collection of about 100 Proteobacteria, 47 strains previously isolated from drinking water, surface water, and wastewater grew in the presence of 200 μMSMX, and were further studied. Out of these, 14 strains, mostly from mineral drinking water, transformed SMX into equimolar amounts of the lesser toxic derivative N4-acetyl-sulfamethoxazole. The highest percentage of SMX transformation was recorded for two strains affiliated to Pseudomonas mandelii. For P. mandelii McBPA4 higher SMX transformation rate and extent were observed in fed-batch (∼8 μMSMX/h, 81%) than in batch conditions (∼5 μMSMX/h, 25%), but similar specific transformation rates were found in both cultivation modes (∼20 μmolSMX/gcell dry weight/h), indicating the dependence of the process on the microbial load. These results evidence that the capacity to transform synthetic antibiotics may be common among bacteria and highlight the potential of environmental bacteria in attenuating the potential adverse effects of pollution with sulfonamides.
- Utilização de proteases de Centaurea calcitrapa L. no fabrico de queijo de vaca: efeitos microbiológicosPublication . Reis, Patrícia J. M.; Lourenço, Pedro L.; Domingos, Ana; Clemente, Alda; Malcata, F. Xavier