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We investigated the relationship among environmental variables, composition, and structure of bacterial communities in different habitats in a mangrove located nearby to an oil exploitation area, aiming to retrieve the natural pattern of bacterial communities in this ecosystem. The T-RFLP analysis showed a high diversity of bacterial populations and an increase in the bacterial richness from habitats closer to the sea and without vegetation (S1) to habitats covered by Avicennia schaueriana (S2) and Rhizophora mangle (S3). Environmental variables in S1 and S2 were more similar than in S3; however, when comparing the bacterial compositions, S2 and S3 shared more OTUs between them, suggesting that the presence of vegetation is an important factor in shaping these bacterial communities. In silico analyses of the fragments revealed a high diversity of the class Gammaproteobacteria in the 3 sites, although in general they presented quite different bacterial composition, which is probably shaped by the specificities of each habitat. This study shows that microhabitats inside of a mangrove ecosystem harbor diverse and distinct microbiota, reinforcing the need to conserve these ecosystems as a whole.

Some marine animals have a dynamic mutualistic association involving heterotrophic coral animals (hosts) and autotrophic dinoflagellate endosymbionts in the genus Symbiodinium, known as zooxanthellae, which are directly involved in their physiology. Currently, there is limited knowledge of the Symbiodinium diversity associated with zoanthids from the Brazilian coast. Hence, this study assessed the diversity of zooxanthellae associated with Palythoa caribaeorum, Zoanthus sociatus and Protopalythoa variabilis commonly found on the northeast coast. Zoanthids samples were collected from sandstone reefs, and the total DNA from the samples was extracted. Diversity was assessed by denaturing gradient gel electrophoresis (DGGE) and ITS region cloning library. Data from ITS region sequences showed that zoanthids hosted two phylogenetic subclades or subgenus (C1 and A3) closely related to Symbiodinium from previous studies. Subclade C1 was found in Pa. caribaeorum, Pr. variabilis and Z. sociatus, while subclade A3 was found exclusively in Z. sociatus. This suggests that Pa. caribaeorum and Pr. variabilis are extremely selective, whereas Z. sociatus shows greater flexibility in the selection of its symbionts, and these differences may be involved with living in different reef environments. Knowledge of zooxanthellae diversity associated with zoanthids can explain their large distribution in Brazilian coast and contribute to a better understanding of zoanthid's sensitivity to thermal stress.

This study investigated the aerobic degradation of phenol by yeast strains isolated from an oil refinery wastewater from the Northeast of Brazil. The samples displayed low fungal diversity, as only yeast colonies were detected on Sabouraud dextrose agar containing chloramphenicol 0.05% (w/v). Among the isolates, three yeast strains were selected to be evaluated for their potential for degrading high phenol concentrations. These species were identified through morphological and biochemical characteristics as Candida tropicalis, C. rugosa, and Pichia membranaefaciens. Although the strains were able to degrade the phenol concentration present in the wastewater, which was 7 mg l(-1), only C. tropicalis was capable of growing at high concentrations of phenol such as 500 mg l(-1 )and 1,000 mg l(-1) in a mineral medium containing this pollutant as the only carbon source. C. rugosa and P. membranaefaciens were inhibited in the presence of 500 mg l(-1) of phenol. However, a longer incubation time was needed for C. tropicalis strain to degrade 1,000 mg l(-1) of phenol compared to the time required to degrade 500 mg l(-1). Moreover, the strain released a significant amount of polysaccharide biosurfactant in the medium probably to minimize the toxic effect of the high phenol concentration. When challenged with 1,500 and 2,000 mg l(-1 )of phenol, C. tropicalis was unable to grow at the tested conditions. The results indicate that this strain of C. tropicalis can be considered both a good phenol-degrader and biosurfactant-producer. Application of this strain might be useful in bioremediation activities or treatment of phenol-polluted wastewater.

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