ABSTRACT. We report here the occurrence of seasonal changes in the pigmentation of colonies of Siderastrea spp. during bleaching events on coastal reefs in northeastern Brazil. Bleached affected almost 50% of coral colonies analyzed in Cabo Branco reefs (Paraiba state) in the summer of 2005. The same phenomenon was detected along various coastal reefs in northeastern Brazil during the summer of 2007 and 2008. These events were seasonal, and began with the emergence of pale colonies that became pale-pink and then purple during the rainy months. The patterns and intensity of colonies pigmentation changes varied with the studied sites. The decrease in zooxanthellae density and chlorophyll-a content was quantified in the colonies with their pigmentation pattern altered (bleaching). Microbiological analyses revealed higher densities of bacteria in pink colonies (bleached) as compared to brown colonies (normal). Environmental disturbances may lead to the pigmentation changes in Siderastrea spp., but the immediate causes of this phenomenon are not clear and require further investigations. Keywords: zooxanthellae, bacteria, marine ecology, pink colonies, Brazilian reefs.Cambios en la pigmentación de colonias de Siderastrea spp. durante los eventos de blanqueamiento en arrecifes costeros del noreste de Brasil RESUMEN. Se relata aquí la aparición de cambios estacionales en la pigmentación de colonias de Siderastrea spp. durante los eventos de blanqueamiento en arrecifes costeros del noreste de Brasil. En verano de 2005, existían casi 50% de colonias blanqueadas en los corales analizados en Cabo Branco, Estado de Paraíba. El mismo fenómeno se detectó a lo largo de varios arrecifes costeros en el noreste del país durante el verano de 2007 y 2008. Estos eventos son asociados a la variación estacional, que comenzaron con la aparición de colonias pálidas que luego se convirtieron en rosa pálido y después a morado, durante los meses de lluvias. Los patrones e intensidad de los cambios en la pigmentación de las colonias fueron diferentes en los sitios estudiados. La disminución de la densidad de zooxantelas y del contenido de clorofila-a fue cuantificada en las colonias y comparados con el patrón de pigmentación alterada (blanqueo). Los análisis microbiológicos revelaron densidades más altas de bacterias en colonias rosas (blanqueada) en comparación con las colonias marrones (considerados normales). Las alteraciones ambientales pueden conducir a estos cambios de pigmentación en Siderastrea spp., pero las causas inmediatas de este fenómeno no están claras y requieren más investigación. Palabras clave: zooxantelas, bacterias, ecología marina, colonias rosas, arrecifes brasileños.

Cyanobacteria are widely distributed in terrestrial, freshwater and marine environments, and over the past decades have been recognized as a powerful source of bioactive compounds. In this study, some cyanobacterial strains were isolated from samples of seawater, brackish water and tissue of reef benthic invertebrates (zoanthid Protopalythoa variabilis, the sponges Cynachrella sp. and Haliclona sp., the coral Siderastrea stellata, and ascidians), collected at the states of Paraíba and Rio Grande do Norte (Northeast of Brazil), during the period between July 2010 and February 2014. After standard isolation methods, the cultivation of the strains was carried out in acclimatized culture chamber (25 °C) under constant aeration, for 15 days at 12-hour photoperiod, using Conway and BG11 media made with filtered seawater. The cyanobacterial cells were analysed for the microcystin production by the ELISA technique and their ethanolic and methanolic extracts for the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa by the agar well diffusion method. The detection of the mcyB gene, one of the genes related to the microcystin synthesis, was done by the Polymerase Chain Reaction (PCR) technique. The majority of the eighteen cyanobacterial strains belonged to Synechococcaceae Family. The genera of Synechocystis, Synechococcus and Romeria were represented by ten, six and two strains, respectively. The production of microcystins was observed in five strains belonging to the genus Synechocystis. The presence of mcyB gene was detected in 12 strains of cyanobacteria: Synechocystis (three strains), Synechococcus (six strains) and Romeria (two strains). Only one strain (Synechocystis aquatilis) showed both the microcystin production and the mcyB gene presence. The antibacterial activity was observed for one strain of Romeria gracilis, one strain of Synechocystis aquatilis and two strains of Synechococcus sp. The ethanolic extracts of R. gracilis strain and two Synechococcus spp. strains inhibited the growth of P. aeruginosa. Among methanolic extracts of cyanobacteria, only one strain of S. aquatilis showed activity against S. aureus, and one R. gracilis strain against P. aeruginosa. Some cyanobacterial strains studied were positive for the microcystin production and antibacterial activity against pathogenic bacteria S. aureus and P. aeuruginosa, and may be further explored for additional biotechnological applications. Rev. Biol. Trop. 65 (3): 890-899. Epub 2017 September 01.Key words: Synechococcales, extracts, mcyB, cyanobacteria.Cyanobacteria or blue-green algae are photosynthetic prokaryotes widely distributed in almost all habitats, from aquatic marine and freshwater ones to terrestrial environments, being also associated with various marine organisms such as corals and sponges (Glas et al., 2010;Paerl & Paul, 2011).In the last decades, cyanobacteria have been gaining attention in ecology, biochemistry, physiology and molecular biology, because of their high potential for antibiotics and ...

The present study tested the hypothesis that endosymbionts of the zoanthid Palythoa caribaeorum show specific responses in cell density, size, and mitotic index (as proxy for cell population growth) under different environmental conditions (water depth, position within the reef and within the colony). Colony fragments were sampled at the nearshore coastal reefs of Porto de Galinhas and at the oceanic St. Peter and St. Paul's archipelago (SPSP), Brazil. At the coastal reefs, zooxanthellae showed higher density on the reef flat (mean: 2.99 × 10 6 cm −2) than at the back reef (mean: 2.07 × 10 6 cm −2). Zooxanthellae were larger at the center of the colonies (mean: 10.61 µm) than at the edges (mean: 10.11 µm), where younger polyps were found. At SPSP, zooxanthellae showed smaller cell diameters at 3 m depth, than at 5-15 m. Cell size increased with depth, thus enhancing the photosynthetic efficiency of colonies in deeper environments. Strategies and adaptations of these endosymbionts to environmental stressors are discussed. Symbiont distribution patterns shown in this study have fundamental implications for the monitoring of the health of tropical reef ecosystems.

Biodiesel wash water is a contaminating industrial effluent that must be treated prior to disposal. The use of this effluent as a low-cost alternative cultivation medium for microalgae could represent a viable supplementary treatment. We cultivated 11 microalgae species with potential use for biodiesel production to assess their growth capacities in biodiesel industrial washing waters. Only Monoraphidium contortum, Ankistrodesmus sp., Chlorococcum sp., and one unidentified Chlorophyceae species grew effectively in that effluent. M. contortum showed the highest growth capacity and had the second highest fatty acid content (267.9 mg g of DW), predominantly producing palmitic (20.9%), 7,10,13-hexadecatrienoic (14%), oleic (16.2%), linoleic (10.5%), and linolenic acids (23.2%). In the second phase of the experiment, the microalgae were cultivated in biodiesel wash water at 75% of its initial concentration as well as in WC (control) medium. After 21 days of cultivation, 25.8 and 7.2% of the effluent nitrate and phosphate were removed, respectively, and the chemical oxygen demand was diminished by 31.2%. These results suggest the possibility of cultivating biodiesel producing microalgae in industrial wash water effluents.

Microalgae are autotrophs and CO2 fixers with great potential to produce biofuels in a sustainable way, however the high cost of biomass production is a challenge. Mixotrophic growth of microalgae has been presented as a great alternative to achieve economic sustainability. Thus, the present work reports the energetic characterization of S. platensis biomasses cultivated under autotrophic (A) and mixotrophic conditions using cheese whey waste at different concentrations, 2.5 (M2.5), 5.0 (M5) and 10.0% (M10), in order to analyze the potential production of valuable chemicals and bio-oil by TGA/DTG and Py-GC/MS. The biochemical compositions of the studied biomasses were different due to the influence of different culture mediums. As the whey concentration increased, there was an increase in the carbohydrate content and a decrease in the protein content, which influenced the elemental composition, calorific value, TGA and volatile compounds evaluated by Py-GC/MS at 450°C, 550°C and 650°C. Sample M10 had lower protein content and formed a smaller amount of nitrogenates compounds by pyrolysis at all temperatures evaluated. There was a reduction of 43.8% (450º), 45.6% (550ºC) and 23.8% (650ºC) in the formation of nitrogenates compounds in relation to sample A. Moreover, the temperature also showed a considerable effect in the formation of volatile compounds. The highest yields of nitrogenates compounds, phenols and aromatic and non-aromatic hydrocarbons were observed at 650ºC. The oxygenated, and N and O containing compounds decreased as the temperature increased. Hydrocarbons such as toluene, heptadecane and heneicosane were produced by S.platensis pyrolysis, which makes this biomass attractive for production of high quality bio-oil and valuable chemicals. Therefore, the results showed that it is possible to decrease the formation of nitrogen compounds via manipulation of growth conditions and temperature.