Browsing by Issue Date, starting with "2018-09-09"
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- Screening of bacteria and microalgae for bioremediation of florfenicol in aquaculture water streamsPublication . Amorim, Catarina L.; Couto, Ana T.; Castro, Paula M.L.The occurrence of antibacterial agents in natural environment had recently received growing concern due to potential adverse effects on human health and aquatic ecosystems. Florfenicol (FF) is a synthetic phenicol antibiotic, widely used in veterinary medicine for treating diverse infections, and inevitably released into the environment, either from uneaten medicated pelleted feed or through urinary, branchial, and fecal excretion. This is one of the few approved antibiotics for use in aquaculture during both production and processing operations, mainly to prevent and treat bacterial diseases. Up to now, removal of FF has been mainly reported using physical-chemical processes but its removal by biological processes is scarce. Considering that many species of bacteria and microalgae can grow in a wide variety of wastewaters and industrial effluents and have been proven to be efficient in removing nitrogen, phosphorus and other pollutants, there is a niche opportunity to use those microorganisms in bioremediation processes. In this study, the potential of bacteria and microalgae, some isolated from a fish farm, to deal with FF was evaluated. Biodegradation of FF was assessed in batch mode in the presence of a conventional carbon source. Labrys portucalensis F11 could degrade ca. 36% of FF, initially supplied at 12 µM, releasing about 24% of fluoride ion. Several microalgae strains were isolated from sludge and water collected in a fish farm using different nutrient media Screening of microalgae able to cope with FF toxicity is under evaluation using a disc-diffusion type bioassay. Microorganisms able to deal with FF are suitable for application in bioremediation processes towards more efficient biological removal processes.
- Effect of dual anthropogenic stresses on exopolysaccharide production by aerobic granular sludgePublication . Amorim, Catarina L.; Parmaki, Stella; Henriques, Isabel S; Castro, Paula M.L.Industrial wastewater streams are difficult to manage due to their complexity, often containing several organic and inorganic compounds, such as toxic/recalcitrant organics, ammonium and inorganic salts. Aerobic granular sludge (AGS) technology has been widely investigated for the treatment of urban and industrial wastewater and its implementation at full-scale is growing worldwide. AGS is a special type of biofilm, formed via self-aggregation of microorganisms in an extracellular polymeric substances (EPS) matrix. EPS produced by microorganisms are crucial not only for granules formation and stability but also to protect cells against harsh conditions in the living environment which often occur in industrial wastewater streams. In this study, the combined effect of different anthropogenic substances on the EPS production by AGS and on the expression of genes for exopolysaccharide production was evaluated. Short-term (24 h) batch assays were conducted inoculating AGS in synthetic wastewater containing different levels of salt and a pharmaceutical (fluoxetine, diclofenac or carbamazepine at 8 mg L-1). EPS production and its biochemical characterization were followed. The expression of psi and alg genes for exopolysaccharide production was assessed. Differences were found in the EPS production depending on the stress applied. The composition of the EPS produced in terms of carbohydrates, proteins and humic acids was different, depending on the type of water stream. The impact of the stressful situations on the levels of transcripts involved in EPS production is under evaluation. These data could help to understand the role of EPS on the AGS stress response upon its exposure to anthropogenic sources.