Browsing by Author "Alexandrino, Diogo A. M."
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- Actinobacteria from arctic and atlantic deep-sea sediments—biodiversity and bioactive potentialPublication . Ribeiro, Inês ; Antunes, Jorge T. ; Alexandrino, Diogo A. M.; Tomasino, Maria Paola ; Almeida, Eduarda ; Hilário, Ana ; Urbatzka, Ralph ; Leão, Pedro N. ; Mucha, Ana P. ; Carvalho, Maria F.The deep-sea covers over 70% of the Earth’s surface and harbors predominantly uncharacterized bacterial communities. Actinobacteria are the major prokaryotic source of bioactive natural products that find their way into drug discovery programs, and the deep-sea is a promising source of biotechnologically relevant actinobacteria. Previous studies on actinobacteria in deep-sea sediments were either regionally restricted or did not combine a community characterization with the analysis of their bioactive potential. Here we characterized the actinobacterial communities of upper layers of deep-sea sediments from the Arctic and the Atlantic (Azores and Madeira) ocean basins, employing 16S rRNA metabarcoding, and studied the biosynthetic potential of cultivable actinobacteria retrieved from those samples. Metabarcoding analysis showed that the actinobacterial composition varied between the sampled regions, with higher abundance in the Arctic samples but higher diversity in the Atlantic ones. Twenty actinobacterial genera were detected using metabarcoding, as a culture-independent method, while culture-dependent methods only allowed the identification of nine genera. Isolation of actinobacteria resulted on the retrieval of 44 isolates, mainly associated with Brachybacterium, Microbacterium, and Brevibacterium genera. Some of these isolates were only identified on a specific sampled region. Chemical extracts of the actinobacterial isolates were subsequently screened for their antimicrobial, anticancer and anti-inflammatory activities. Extracts from two Streptomyces strains demonstrated activity against Candida albicans. Additionally, eight extracts (obtained from Brachybacterium, Brevibacterium, Microbacterium, Rhodococcus, and Streptomyces isolates) showed significant activity against at least one of the tested cancer cell lines (HepG2 and T-47D). Furthermore, 15 actinobacterial extracts showed anti-inflammatory potential in the RAW 264.4 cell model assay, with no concomitant cytotoxic response. Dereplication and molecular networking analysis of the bioactive actinobacterial extracts showed the presence of some metabolites associated with known natural products, but one of the analyzed clusters did not show any match with the natural products described as responsible for these bioactivities. Overall, we were able to recover taxonomically diverse actinobacteria with different bioactivities from the studied deep-sea samples. The conjugation of culture-dependent and -independent methods allows a better understanding of the actinobacterial diversity of deep-sea environments, which is important for the optimization of approaches to obtain novel chemically-rich isolates.
- Combined effects of temperature and dietary lipid level on body composition, growth, and freshness profile in european seabass, dicentrarchus labraxPublication . Cardoso, Patrícia G.; Gonçalves, Odete; Cavalheri, Thais; Amorim, Vânia E.; Cao, Weiwei; Alexandrino, Diogo A. M.; Jia, Zhongjun; Carvalho, Maria F.; Vaz-Pires, Paulo; Ozório, Rodrigo O. A.The effects of increasing temperature and dietary lipid level on the body composition, growth performance, and freshness profile of the European seabass (Dicentrarchus labrax) were evaluated through a fish trial lasting 56 days. Findings demonstrated that fish reared at 24 °C presented a lower lipid level and a higher daily growth index than those reared at 20 °C. On the other hand, the sea bass condition index did not change among treatments. Additionally, sensory analysis (the Quality Index Method) and microbiological analysis revealed that fish reared at 24 °C showed better freshness conditions than those at 20 °C. Nevertheless, the dietary lipid level did not have any influence on fish freshness conditions. Therefore, our data suggest that the increase in temperature to 24 °C is beneficial for the growth and freshness profile of this particular species in aquaculture.
- Exploring the possible link between fluoride sensitivity and bacterial defluorinationPublication . Maia, Tiago; Carvalho, Maria F.; Alexandrino, Diogo A. M.; Alexandrino, DiogoFluoorganic compounds are ubiquitous environmental pollutants due to their widespread use and high environmental persistence, mostly attributed to the stability of their carbon-fluoride bonds. The biotransformation of these compounds has been observed in some microorganisms, but defluorination (cleavage of carbon-fluorine bonds) remains the limiting step. Intracellular accumulation of fluoride occurs during microbial defluorination, which can cause several toxic effects. This work hypothesizes that intracellular fluoride stress may potentially affect the defluorination process in bacteria, limiting this critical catabolic step for the eventual mineralization of fluoroorganic pollutants. Fluoride sensitivity was first ascertained in defluorinating bacteria Labrys portucalensis F11 and Delftia acidovorans MFA5 (known degraders of fluorobenze1 and fluoroacetate2, respectively), with an Escherichia coli strain as the non-defluorinating control. Sensitivity was tested for increasing concentrations of f luoride (0-0.6 mM NaF) both in oligotrophic (minimal salts medium with acetate) and mesotrophic media (Nutrient Broth), based on bacterial growth inhibition for 48 hours at 28 ºC. After ascertaining their sensitivity thresholds, these strains are now being tested for their defluorination ability, against their preferred fluorinated substrates, when exposed to the NaF concentration with the highest observed growth inhibition. Results showed that fluoride stress was more severe in oligotrophic media, with 0.4 mM NaF presenting the highest growth inhibition among tested strains. Strain MFA5 was also shown to be the least sensitive to fluoride, while F11 was the most affected. Conclusions: Fluoride can exert cytostatic effects even in bacterial strains with proven ability to biodegrade fluorinated compounds. These results will allow to enlighten the ties between fluoride sensitivity and bacterial defluorination, thus broadening the knowledge on influencing factors of a critical catabolic reaction.
- Isolation of Actinomycetes from marine sediments with potential to produce bioactive compoundsPublication . Ribeiro, Inês; Alexandrino, Diogo A. M.; Oliveira, Rui S.; Santos, Chiara; Pereira, Filipe; Mucha, Ana P.; Carvalho, Maria F.The various health problems experienced by the humanity, together with an increasing number of antibiotic-resistant microorganisms have been driven scientists to look for additional reserves of new bioactive substances. Actinomycetes are an important source of bioactive compounds with industrial and pharmaceutical interest. The distribution of this vast microbial group in the oceans is largely unexplored, making oceans an untapped and promising source of novel bioactive compounds.
- Microbial degradation of Sodium Trifluoroacetate under aerobic and anaerobic conditionsPublication . Alexandrino, Diogo A. M.; Oliveira, Rui S.; Carvalho, M. FátimaThe extensive use of hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) as environmental acceptable alternatives to chlorofluorocarbons (CFCs) has been responsible for the introduction in the environment of significant amounts of Trifluoroacetate (TFA). Specifically, TFA is produced by the atmospheric breakdown of HCFC-123, HCFC-124, HFC-134a and HFO-1234yf, which undergo oxidative, photolytic and hydrolytic reactions to generate the compound. TFA is a highly persistent, water soluble and extremely stable fluorinated compound, that tends to accumulate in low-streamed aquatic environments, with marine ecosystems as its ultimate environmental sink. Although it does not exert considerable toxicological effects neither in microbial communities, nor in aquatic organisms, it reveals a mild toxicity regarding plants (Boutonnetet al. , 1999). There are no reports on the aerobic biodegradation of TFA, but the mineralisation of the compound by anaerobic methanogenic bacteria was demonstrated in few studies (Visscher, et al ., 1994; Kim et al., 2000).