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- Studies on Hydrogen Sulfide Oxidase from Pseudomonas sp.Publication . Novo, Ana; Antunes, Filipa; Baptista, Inês; Jorge, Ruben; Saraiva, Isabel; Moreira, Irina S.; Castro, Paula M. L.
- Hydrogen sulfide biological oxidation by pure cultures of heterotrophic bacteriaPublication . Novo, Ana; Antunes, Filipa; Baptista, Inês; Jorge, Ruben; Saraiva, Isabel; Moreira, Irina S.; Castro, Paula M. L.Biogas is a mixture of gases produced during anaerobic treatment of sludge whose composition depends on the type of digested materials as well as on the operating conditions of bioreactor. This consists mainly of CH4 and CO2, but components such as H2S is of particular interest due to its corrosive, toxic and environmentally hazardous properties. Removal of H2S present in biogas can be achieved through physical and chemical processes, which are effective but produce secondary waste, which in turn gives rise to another problem of pollution. Biological treatment can be used to removing H2S using different species of microorganisms whose specific enzymes catalyze the biological oxidation of H2S, including photoautotrophic and chemotrophs organisms. This work aims to compare the biotechnological removal of H2S from biogas in aerobic conditions through heterotrophic microbial biomass and biocatalytic treatments. Heterotrophic microorganisms were isolated from microbial enrichments supplied with H2S streams from a wastewater treatment plant and were characterized based on their ability to grow in mineral medium with acetate as source of carbon. Isolates retrieved were mainly affiliated to the class of γ-proteobacteria with a strong prevalence of the genus Pseudomonas. Isolates A9, B9 and C1 all identified as Pseudomonas spp., revealed as the species with higher potential for H2S removal, growing at concentrations of H2S up to 16 mM. Total protein profiles were screened by SDS-PAGE for the three isolates, before and after the addition of H2S, with the aim of purifying enzyme fractions involved in the oxidation process.
- In vitro intestinal absorption of amino acid mixtures extracted from codfish (Gadus morhua L.) salting wastewaterPublication . Ferraro, Vincenza; Jorge, Ruben Ferreira; Cruz, Isabel B.; Antunes, Filipa; Sarmento, Bruno; Castro, Paula M. L.; Pintado, Manuela E.This study reports on the intestinal permeability of salt-containing mixtures of amino acids extracted from codfish salting wastewater. Permeability was evaluated in vitro using the Caco-2 cell line model; cell integrity during exposure to mixtures of amino acids was estimated by measuring the transepithelial electrical resistance (TEER). The effect of salt (NaCl) on the permeability and on the intestinal cell’s integrity was also examined. Permeation rate (i.e. transport) was ≥95% for all amino acids except for creatine, for which it was 6%. Values for apparent permeability coefficients, Papp > 10 5 cm s 1, for mixture with isotonic concentration of NaCl suggest that amino acids are very likely to be absorbed in humans. Mixture with a hypertonic level of NaCl exerts a cytotoxic effect in intestinal cells resulting in a loss of epithelium integrity. Results show that isotonic mixture of amino acids extracted from codfish salting wastewater could be used in food, feed, cosmetic and pharmaceutical formulations. These applications could contribute to the fish industry sustainability.