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EPS production by bacteria from high salinity wastewater.

Publication . Paulo, Ana M.S.; Amorim, Catarina L.; Castro, Paula M.L.

Aerobic granular sludge (AGS) is a promising technology for treating industrial wastewater, possessing higher biomass retention and tolerance to toxic substrates than conventional activated sludge systems. The presence of extracellular polymeric substances (EPS) in the aerobic granules structure increases the bacterial protection towards stress conditions and the stability of granules. Several industrial wastewaters contain high salt concentrations in their composition, which can inhibit the bacteria responsible for nutrients removal in the AGS process [1]. A novel strategy to increase the robustness of the system to high salinity is to bioaugment the aerobic granules with halotolerant bacteria with ability to produce EPS. Using a robust AGS process, extra value can be obtained from the wastewater since the EPS from the biomass can be recovered and used as new biomaterials in different applications. The aim of the present study is to investigate the feasibility of EPS production by halotolerant bacteria isolated from high salinity wastewater collected in a fish canning industry. Bacterial isolates obtained from the saline water were grouped according to species similarity, based on RAPD profiles. Isolates displaying unique RAPD profiles were subsequently identified by 16S rRNA gene sequencing analysis. The potential for EPS production by isolates presenting a sticky growth on agar plates is currently being evaluated. The content in proteins, humic acids and carbohydrates of the extracted EPS is quantified using reference methods. The obtained isolates are closely related to bacterial strains from the Acinetobacter, Psychrobacter, Arthrobacter, Bacillus, Exiguobacterium and Kocuria genera. The isolated halotolerant bacteria present different ability to produce EPS. The most promising EPS producers will be used for bioaugmentation of an AGS process treating high salinity wastewater. Valorization of the wastewater through EPS recovery from the AGS is in line with the circular economy concept.

2017-12-07Conference object

Open access

Analytical microsystem for the spectrophotometric determination of titratable acidity in wines

Publication . Sandez, Natalia; Calvo-López, Antonio; Vidigal, Susana S. M. P.; Alonso-Chamarro, Julian; Rangel, António O. S. S.

2018Conference object

Open access

Investigating the impact of UV-C/H2O2 and sunlight/H2O2 on the removal of antibiotics, antibiotic resistance determinants and toxicity present in urban wastewater

Publication . G. Michael, Stella; Michael-Kordatou, Irene; Nahim-Granados, Samira; Polo-López, Maria Inmaculada; Rocha, Jaqueline; Martínez-Piernas, Ana B.; Fatta-Kassinos, Pilar; Manaia, Célia M.

This work aimed at exploring the impact of UV-C/H2O2 and sunlight/H2O2 processes, applied at pilot scale, on removing: (i) ciprofloxacin and sulfamethoxazole, (ii) cultivable Escherichia coli and Pseudomonas aeruginosa grown in the presence and absence of sub-minimal inhibitory concentrations of ciprofloxacin and sulfamethoxazole and (iii) the genes 16S rRNA and selected antibiotic resistance genes (ARGs) (i.e., sul1, blaCTX-M, qnrS, tetM, etc.) from urban wastewater. The major antibiotic transformation products (TPs) formed, were elucidated and the chronic toxicity of the whole effluent mixture against Vibrio fischeri was evaluated. The capability of the processes, in terms of the elimination of the antibiotics present in urban wastewater, varied among the two light sources used: both antibiotics were fully removed during UV-C/Η2Ο2, whereas only ciprofloxacin was removed during the sunlight/H2O2. The photo-transformation of the antibiotics led to the identification of 21 and 18 TPs of ciprofloxacin and sulfamethoxazole, respectively, while all of them retained their core moiety, responsible for the antibacterial activity. All the UV-C/H2O2-treated samples were found to be toxic, whereas the luminescence of V. fischeri was not inhibited when tested in the sunlight/H2O2-treated samples. During both processes, E. coli, P. aeruginosa and the colonies of these species still viable in the presence of antibiotics, were successfully inactivated to values below the detection limit. However, sunlight/H2O2 has not achieved complete disinfection, as regrowth of E. coli and P. aeruginosa colonies was observed after 48 h of storage of the treated effluent. Finally, none of the technologies tested was able to completely remove the target ARGs, confirming their inability to prevent the spread of resistance determinants to the environment.

2020Journal article

Restricted access

Hydrothermal–microwave processing for starch extraction from mexican avocado seeds: operational conditions and characterization

Publication . Araújo, Rafael G.; Rodríguez-Jasso, Rosa M.; Ruiz, Héctor A.; Govea-Salas, Mayela; Rosas-Flores, Walfred; Aguilar-González, Miguel Angel; Aguilar, Cristobal Noe; Pintado, Manuela E.

Avocado seeds are an agroindustrial residue widely produced in Mexico that are causing various environmental problems due to their accumulation. The evaluation of avocado residues to recover biopolymers by microwave-assisted extraction (MAE) and the characterization of avocado starch properties were studied in the present work. A central-composite design was used to optimize the MAE process. Moreover, a comparison was performed between MAE non-isothermal mode (NO–ISO) and conventional extraction. Starch optimization by MAE was obtained at 161.09 °C for 56.23 min with an extraction yield of 49.52% ± 0.69%, while with NO–ISO at 161 °C was obtained 45.75% ± 2.18%. Conventional extraction was 39.04% ± 2.22%. Compared with conventional starch, MAE starch showed similar proprieties and molecular spectra. In contrast, MAE starch showed high solubility, low water absorption capacity, a non-granular structure with small particle size (<2 μm) and polydispersity of fragments at different sizes of polymers. Therefore, MAE is a viable technology to extract the starch, and avocado seed can be considered an excellent starch source for the development of novel functional foods, contributing to promoting sustainability across the food chain.

2020Journal article

Open access

Colour profile analysis of Port Wines by different instrumental and visual methods

Publication . Soares-da-Silva, Francisco A. G.; Campos, Francisco M.; Ferreira, Manuel L.; Ribeiro, Natália; Amaral, Bento; Simões, Tomás; Silva, Cristina L. M.

BACKGROUND: Wine colour is an important quality parameter, being the first sensorial attribute evaluated during wine tasting. The perception of wine colour can be different depending on many factors, including the depth of the sample under observation. The main objectives of the present study were to measure the colour of Port wines, using CIE L*a*b* parameters at different depths with different instrumental techniques (spectrophotometry and colorimetry), and to compare the obtained results with the sensory (visual) perception of colour samples. RESULTS: Representative profiles of Lightness (L*), Hue (H*) and Chroma (C*) at different depths were obtained using Port wine samples from different categories and ages. In general, relatively good correlations between the colorimetric and spectrophotometric methods were obtained for the L* and H* parameters. The results of the sensory tests also showed good correlations between the visually-assessed hue scores and the colorimetric measurements of the H* parameter, particularly at the lower depths tested (up to 4.0 mm). CONCLUSIONS: Overall, the results indicate that the colorimetric method can be used for estimating wine colour parameters, providing useful information about the colour profile of wines at different depths

2019Journal article

Open access