Centre for Biotechnology and Fine Chemistry

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Publications

Oxygen vacancies, the optical band gap (Eg) and photocatalysis ofhydroxyapatite: Comparing modelling with measured data

Publication . Bystrov, V. S.; Piccirillo, C.; Tobaldi, D. M.; Castro, P. M. L.; Coutinho, J.; Kopyl, S.; Pullar, R.

Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) is a calcium phosphate employed both in biomedicine and forenvironmental remediation. It is known that HAp can also be photocatalytic under UV light, probablydue to oxygen deficiencies, but the mechanism is unclear, and reported optical band gap energies varygreatly. For the first time we propose the mechanisms and precise kinds of vacancies which may causethe photocatalytic activity of HAp, and compare these theoretical data with our measured data on bothsamples of marine origin and commercial HAp powders. Density functional theory (DFT) (from firstprinciples calculations and Density of States (DOS) modelling) was used to calculate the optical bandgap energy (Eg) created by various possible oxygen vacancies in the HAp lattice: O from PO4, O fromOH, the loss of an entire OH group, or the simultaneous loss of O from PO4and an entire OH group. Themodelled values match the measured values very closely, suggesting that in non-photocatalytic HAp, ifany vacancies exist, they are O atoms from the OH group, resulting in a band gap of ∼5 eV in the UVCregion (not present in solar light at the Earth’s surface). However, in photocatalytic HAp, reduction fromthe combustion of an organic component at 1000◦C led to oxygen deficiency in the phosphate groups,probably in the O15 position, giving an Egof ∼3.45 eV, in the UVA region (present in sunlight). HeatingHAp with no organic component to 1200◦C also led to vacancies, of both an entire OH group and oxygenfrom PO4groups, which led to an intermediate Egvalue of ∼4 eV, on the boundary of the UVA-UVB regions.Absorption peaks were also predicted in the visible-light region with some types of vacancy.

2016Journal article

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Photocatalytic ozonation of urban wastewater and surface water using immobilized TiO2 with LEDs: Micropollutants, antibiotic resistance genes and estrogenic activity

Publication . Moreira, Nuno F.F.; Sousa, José M.; Macedo, Gonçalo; Ribeiro, Ana R.; Barreiros, Luisa; Pedrosa, Marta; Faria, Joaquim L.; Pereira, M. Fernando R.; Castro-Silva, Sérgio; Segundo, Marcela A.; Manaia, Célia M.; Nunes, Olga C.; Silva, Adrián M.T.

Photocatalytic ozonation was employed for the first time in continuous mode with TiO2-coated glass Raschig rings and light emitting diodes (LEDs) to treat urban wastewater as well as surface water collected from the supply area of a drinking water treatment plant (DWTP). Different levels of contamination and types of contaminants were considered in this work, including chemical priority substances (PSs) and contaminants of emerging concern (CECs), as well as potential human opportunistic antibiotic resistant bacteria and their genes (ARB&ARG). Photocatalytic ozonation was more effective than single ozonation (or even than TiO2 catalytic ozonation) in the degradation of typical reaction by-products (such as oxalic acid), and more effective than photocatalysis to remove the parent micropollutants determined in urban wastewater. In fact, only fluoxetine, clarithromycin, erythromycin and 17-alpha-ethinylestradiol (EE2) were detected after photocatalytic ozonation, by using solid-phase extraction (SPE) pre-concentration and LC-MS/MS analysis. In surface water, this treatment allowed the removal of all determined micropollutants to levels below the limit of detection (0.01-0.20 ng L(-1)). The efficiency of this process was then assessed based on the capacity to remove different groups of cultivable microorganisms and housekeeping (16S rRNA) and antibiotic resistance or related genes (intI1, blaTEM, qnrS, sul1). Photocatalytic ozonation was observed to efficiently remove microorganisms and ARGs. Although after storage total heterotrophic and ARB (to ciprofloxacin, gentamicin, meropenem), fungi, and the genes 16S rRNA and intI1, increased to values close to the pre-treatment levels, the ARGs (blaTEM, qnrS and sul1) were reduced to levels below/close to the quantification limit even after 3-days storage of treated surface water or wastewater. Yeast estrogen screen (YES), thiazolyl blue tetrazolium reduction (MTT) and lactate dehydrogenase (LDH) assays were also performed before and after photocatalytic ozonation to evaluate the potential estrogenic activity, the cellular metabolic activity and the cell viability. Compounds with estrogenic effects and significant differences concerning cell viability were not observed in any case. A slight cytotoxicity was only detected for Caco-2 and hCMEC/D3 cell lines after treatment of the urban wastewater, but not for L929 fibroblasts.

2016Journal article

Open access

Functional characterisation and sensory evaluation of a novel symbiotic okara beverage

Publication . Voss, Glenise B.; Monteiro, Maria João P.; Jauregi, Paula; Valente, Luísa M.P.; Pintado, Manuela E.

This study aimed to produce four different beverages from okara (soybean by-product) previously hydrolyzed by Cynara cardunculus enzymes and fermented by probiotic bacteria or unfermented beverage. The probiotic viable cells, the isoflavones profile and organic acids were evaluated in the okara beverage. In addition, total phenolic content, antioxidant and ACE inhibitory activities were evaluated at storage time and during in vitro gastrointestinal digestion of all beverages. The probiotic was viable throughout storage in all fermented beverages. The significant bioconversion of the isoflavone glycosides into their corresponding bioactive aglycones was observed in fermented beverage. Furthermore, the beverages showed a good ACE inhibitory activity. After gastrointestinal tract, all beverages showed an increase in the antioxidant and ACE inhibitory activities. In conclusion, this study shows that the application of okara for a multifunctional beverage could be a promising strategy in the disease prevention and contribution to a zero waste approach in food industry.

2021Journal article

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Draft genome sequences of two Ralstonia pickettii strains with different aminoglycoside resistance phenotypes

Publication . Vaz-Moreira, Ivone; Tamames, J.; Martinez, J.L.; Manaia, C. M.

The genomes of two Ralstonia pickettii strains (H2Cu2 and H2Cu5), isolated from hospital effluent in a selective medium containing CuSO4, were sequenced. They presented MICs of>256 and 6g/ml for the aminoglycoside gentamicin, respectively. The 5.2-Mb draft genomes have 40 contigs for strain H2Cu2 and 113 for H2Cu5.

2016Journal article

Open access

Lactobacillus mulieris sp. nov., a new species of Lactobacillus delbrueckii group

Publication . Rocha, Joana; Botelho, João; Ksiezarek, Magdalena; Ugarcina Perovic, Svetlana; Machado, Miguel; Carrico, João André; Pimentel, Lígia L.; Salsinha, Sofia; Rodríguez-Alcalá, Luis M.; Pintado, Manuela; Ribeiro, Teresa G.; Peixe, Luísa

One Gram-stain-positive, non-motile, non-spore-forming, catalase-negative, and coccobacilli-shaped strain, designated c10Ua161MT, was isolated from a urine sample from a reproductive-age healthy woman. Comparative 16S rRNA gene sequence analysis indicated that strain c10Ua161MT belonged to the genus Lactobacillus . Phylogenetic analysis based on pheS and rpoA gene sequences strongly supported a clade encompassing strains c10Ua161MT and eight other strains from public databases, distinct from currently recognized species of the genus Lactobacillus. In silico Average Nucleotide Identity (ANI) and Genome-to-Genome Distance Calculator (GGDC), showed 87.9 and 34.3 % identity to the closest relative Lactobacillus jensenii , respectively. The major fatty acids of strain c10Ua161MT were C18 : 1ω9c (65.0%), C16 : 0 (17.8%), and summed feature 8 (10.2 %; comprising C18 : 1ω7c, and/or C18 : 1ω6c). The DNA G+C content of the strains is 34.2 mol%. On the basis of data presented here, strain c10Ua161MT represents a novel species of the genus Lactobacillus , for which the name Lactobacillus mulieris sp. nov. is proposed. The type strain is c10Ua161MT (=CECT 9755T=DSM 108704T).

2020Journal article

Restricted access