Miriam Araujo Carlos Crapez

Bio: Miriam Araujo Carlos Crapez is an academic researcher from Federal Fluminense University. The author has contributed to research in topics: Organic matter & Environmental chemistry. The author has an hindex of 4, co-authored 5 publications receiving 278 citations.

Induction of halogenated vesicle transport in cells of the red seaweed Laurencia obtusa

Abstract: In clones of the red alga Laurencia obtusa, the frequency of vesicle transport from corps en cerise (CC) to the cell wall region was evaluated in response to differences in temperature, irradiance, desiccation, bacterial fouling, and bromine (Br) availability. In addition, the morphology of the corps en cerise was analyzed. Traffic of vesicles was induced by exposing L. obtusa to low temperatures and variations in irradiance. It was also verified that bacterial fouling induced vesicle traffic. Under high temperatures and desiccation, the membranous tubular connections were lost and transport of vesicles was not seen. The morphology of the corps en cerise varied according to the availability of Br in seawater. Exocytosis of secondary metabolites by L. obtusa was shown to vary in relation to temperature, irradiance, desiccation and bacterial fouling. The data suggest that the transport of vesicles in L. obtusa may be related to the inhibition of the microfouling community on the algal surface.

Role of bacterial esterase on mercury dynamics in mangrove sediments

Abstract: Tropical estuarine areas present microbial and geochemical conditions that have been pointed out as important conditions to trigger the mechanisms of mercury methylation improving its bioavailability to higher trophic levels. Despite the potential risk of these mechanisms to human health, few studies have reported in situ analysis in costal subtropical ecosystems, relating bacterial activity and mercury concentrations. In the present work we analyze the relationship between some relevant environmental parameters that may stimulate the bacterial activity and control mercury concentrations in the sediments of a tropical mangrove tidal flat. Forty-four samples were collected and analyzed for total organic carbon, bacterial organic carbon, lipids, proteins, esterase activity and mercury concentrations and SEM/AVS. The redox potential, temperature and pH were also measured in situ. The results showed intense bacterial activity and increasing mercury levels when compared with local backgrounds. The use of SEM/AVS indicator recommended by USEPA as a criterium to check the sediment quality, did not show enough accuracy to predict the ecological bioavailability risk in sediments with high organic matter content. This methodology requires new approach to help decision making.

Chemical interactions between marine macroalgae and bacteria

Abstract: We review research from the last 40 yr on macroalgal–bacterial interactions. Marine macroalgae have been challenged throughout their evolution by microorganisms and have developed in a world of microbes. Therefore, it is not surprising that a complex array of interactions has evolved between macroalgae and bacteria which basically depends on chemical interactions of various kinds. Bacteria specifically associate with particular macroalgal species and even to certain parts of the algal body. Although the mechanisms of this specificity have not yet been fully elucidated, ecological functions have been demonstrated for some of the associations. Though some of the chemical response mechanisms can be clearly attributed to either the alga or to its epibiont, in many cases the producers as well as the mechanisms triggering the biosynthesis of the biologically active compounds remain ambiguous. Positive macroalgal–bacterial interactions include phytohormone production, morphogenesis of macroalgae triggered by bacterial products, specific antibiotic activities affecting epibionts and elicitation of oxidative burst mechanisms. Some bacteria are able to prevent biofouling or pathogen invasion, or extend the defense mechanisms of the macroalgae itself. Deleterious macroalgal–bacterial interactions induce or generate algal diseases. To inhibit settlement, growth and biofilm formation by bacteria, macroalgae influence bacterial metabolism and quorum sensing, and produce antibiotic compounds. There is a strong need to investigate the bacterial communities living on different coexisting macroalgae using new technologies, but also to investigate the production, localization and secretion of the biological active metabolites involved in those possible ecological interactions.

Biodegradation alternative in the cleanup of petroleum hydrocarbon pollutants

Abstract: Extensive petroleum hydrocarbon exploration activities often result in the pollution of the environment, which could lead to disastrous consequences for the biotic and abiotic components of the ecosystem if not restored. Remediation of petroleum-contaminated system could be achieved by either physicochemical or biological methods. However, the attendant negative consequences of the physicochemical approach are currently directing greater attention to the exploitation of the biological alternatives. This paper provides a review of the menace of petroleum hydrocarbon pollution and its biodegradation in the environment with the view of understanding the biodegradation processes for better exploitation in bioremediation challenges. Key words: Petroleum hydrocarbon, pollution, environment, and biodegradation.

Mangrove bacterial diversity and the impact of oil contamination revealed by pyrosequencing: bacterial proxies for oil pollution.

Abstract: Background: Mangroves are transitional coastal ecosystems in tropical and sub-tropical regions and represent biologically important and productive ecosystems. Despite their great ecological and economic importance, mangroves are often situated in areas of high anthropogenic influence, being exposed to pollutants, such as those released by oil spills. Methodology/Principal Findings: A microcosm experiment was conducted, which simulated an oil spill in previously pristine mangrove sediment. The effect of the oil spill on the extant microbial community was studied using direct pyrosequencing. Extensive bacterial diversity was observed in the pristine mangrove sediment, even after oil contamination. The number of different OTUs only detected in contaminated samples was significantly higher than the number of OTUs only detected in non-contaminated samples. The phylum Proteobacteria, in particular the classes Gammaproteobacteria and Deltaproteobacteria, were prevalent before and after the simulated oil spill. On the other hand, the order Chromatiales and the genus Haliea decreased upon exposure to 2 and 5% oil, these are proposed as sensitive indicators of oil contamination. Three other genera, Marinobacterium, Marinobacter and Cycloclasticus increased their prevalence when confronted with oil. These groups are possible targets for the biomonitoring of the impact of oil in mangrove settings. Conclusions/Significance: We suggest the use of sequences of the selected genera as proxies for oil pollution, using qPCR assessments. The quantification of these genera in distinct mangrove systems in relation to the local oil levels would permit the evaluation of the level of perturbance of mangroves, being useful in field monitoring. Considering the importance of mangroves to many other environments and the susceptibility of such areas to oil spills this manuscript will be of broad interest.