Degradação de Óleo por Bactérias Isoladas dos Sedimentos de Manguezal da A.P.A. de Guapimirim - Baía de Guanabara - RJ - Brasil

In the present work the in situ petroleum remediation in a mangrove ecosystem was evaluated, comparing the natural and stimulated degradation by hydrocarbonoclastic bacteria consortia (HBC) isolated from sediment samples. 9 microcosms experiments were installed in the Guapimirim Environmental Protection Area (Guanabara Bay): 3 experiments were control, 3 were contaminated only with petroleum (SP) and 3 were contaminated with petroleum and with the application of the HBCs isolated from this site (PB). The petroleum effect on microorganisms activity was evaluated by analysis of Electon Transport System Activity and the activity of exoenzymes esterases . The evaluation of oil biodegradation was done by the analysis of hydrocarbons (soxhlet microwaves extractions and chromatography gas spectrometry with mass detection). The population diversity of hydrocarbonoclastic communities (of microcosms SP and CBHs) was carried out by analysing the terminal restriction fragment lenght polimorphism (t-RFLP). The isolated hydrocarbonoclastic bacteria that grew on oil hydrocarbons (octadecane, pristane, naphthalene, fluoranthene e pyrene) as the only source of carbon and energy, were identified by gene sequencing of rDNA 16S. The oil degradation was only observed after 3 months from the oil treatment, suggesting a long lag fase for microorganism to adapt to the petroleum on the tested natural condictions. Eleven strains were isolated from HBCs and 53 from the microcosm sediment samples (SP). This is the first time that hydrocarbonoclastic strains have ever been isolated from Guanabara Bay, what shows the high potential of this environment for developing auto-recovery mechanisms. The phylogenetic characterization showed that, among the 64 strains, there were 25 different species (of 15 distinct genera). Some of them are recognized for their hydrocarbon degrading ability (e.g., Marinobacter sp. and Alcanivorax sp). Though, for some genera, it is the first time that this ability was observed (like Hydrothermal vent). In addition, for the strains that grew on polycyclic aromatic hydrocarbons the presence of dioxygenase gene was observed (sub-unity gamma and beta nahAc nahAd of a naphthalene-dioxigenase from Pseudomonas sp. 9816-4, U49496), undelining the degrading potential of such species and suggesting the presence of horizontal transfer among the isolated strains.Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorFoi realizada uma avaliação da biorremediação in situ da contaminação por petróleo em um ecossistema de manguezal, comparando a degradação natural com a degradação estimulada por consórcios bacterianos hidrocarbonoclásticos (CBHs) isolados a partir de amostras de sedimento. Nove experimentos em microcosmos foram instalados na Área de Proteção Ambiental Guapimirim (Baía de Guanabara): 3 experimentos foram controle, 3 foram contaminados somente com petróleo (SP) e 3 foram contaminados com petróleo e com a aplicação dos CBHs isolados deste manguezal (PB). O efeito do petróleo sobre a atividade bacteriana foi avaliado a partir da medição da atividade do sistema transportador de elétrons e da atividade das exoenzimas esterases. A avaliação da biodegradação do óleo foi feita pela análise dos hidrocarbonetos (extração em soxhlet-microondas e determinação por cromatografia gasosa e espectrometria de massa). Além disto, foi feito estudo da diversidade populacional das comunidades hidrocarbonocláticas (dos microcosmos SP e CBHs). Foi analisado o polimorfismo do comprimento terminal do fragmento de restrição(t-RFLP). As bactérias hidrocarbonocláticas isoladas em meio contendo somente HCs de petróleo (octadecano, pristano, naftaleno, fluoreno e pireno) como fonte de carbono e energia, foram identificadas a partir da sequência gênica do DNAr 16S. A degradação do petróleo somente começou a ser observada no final de três meses, sugerindo um longo período de adaptação da microbiota ao petróleo em condições experimentais naturais testadas. Foram isoladas 11 cepas dos CBHs e 53 a partir das amostras de sedimento dos microcosmos SP, das quais 38 são hidrocarbonoclásticas. Esta é a primeira vez que cepas hidrocarbonoclásticas são isoladas da Baía de Guanabara, o que mostra o potencial deste ambiente em encontrar mecanismos de auto-depuração. A caracterização filogenética revelou que, dentre as 64 cepas, havia 25 espécies diferentes (de 15 gêneros distintos). Alguns dos gêneros observados são reconhecidos por degradarem HCs (por exemplo, Marinobacter sp. e Alcanivorax sp.). Entretanto foi observada a presença de alguns gêneros para os quais é a primeira vez que esta habilidade foi observada (por exemplo, Hydrothermal sp). Adicionalmente, para as cepas isoladas sobre os HPAs foi observada a presença do gene para dioxigenases (subunidade Y e B nahAc nahAd da naftaleno-dioxigenase de Pseudomonas sp. 9816-4, U49496), reforçando o potencial hidrocarbonoclástico e sugerindo a presença de transfer horizontal entre as cepas isoladas

Persistent organic pollutants in two reservoirs along the Paraíba do Sul-Guandu River system, Rio de Janeiro, Brazil

Sediment contamination is evaluated by determining organic micropollutants (organochlorine compounds - OCs and polycyclic aromatic hydrocarbons - PAHs) in two important Brazilian water reservoirs. Trace levels of OCs were observed in the Santana reservoir (44.8 ng g-1 d.w. of p,p'-DDT), while in the Funil reservoir the levels were below detection level. Forty-eight percent of the found sigmaocs were polychlorinated biphenyls, 29% dichlorodiphenyltrichloroethane (DDT), 18% Drins, and 5% other pesticides (HCB, Heptachlor, Heptachlor-epoxide, gamma-HCH and a-Endosulfan). We observed lower levels of sigmaPAH in the Funil reservoir (1 to 275 ng g-1d.w.) than in the Santana reservoir (2.2 to 26.7 µg g-1 d.w.)

Fluoroquinolone Antibiotics and their Interactions in Agricultural Soils – A Review

Fluoroquinolones (FQs) are antibiotics widely used in human and veterinary medicine. The main sources of FQ contamination in agricultural soils result from the irrigation of fields with wastewater and the use of waste sludge and animal manure as fertilizer. Due to their physicochemical properties, these chemicals exhibit strong sorption in soils, presenting low mobility, high persistence and, therefore, long-term biological action in this matrix. This review addresses their main physicochemical and biological interactions in soils, as well as their main biotic and abiotic degradation pathways. In addition, we highlight the possible impacts of FQs on organisms that play an important role in the maintenance of biogeochemical cycles such as soil microbiota, earthworms, and plants. Routes of exposure to human beings through food grown in contaminated soils, and possible exposure to resistant genes derived from microbiota-soil-antibiotic interactions are also discussed. This review emphasizes the need for establishing regulatory limits on FQ contamination sources through fertilization with human and husbandry waste in agriculture soils. DOI: http://dx.doi.org/10.17807/orbital.v11i1.1352<br /

Bacterial diversity of an acid mine drainage beside the Xichú River (Mexico) accessed by culture-dependent and culture-independent approaches

International audienceXichú River is a Mexican river located in an environmental preservation area called Sierra Gorda Biosphere Reserve. Around it, there are tons of abandoned mine residues that represent a serious environmental issue. Sediment samples of Xichú River, visibly contaminated by flows of an acid mine drainage, were collected to study their prokaryotic diversity. The study was based on both cultural and non-cultural approaches. The analysis of total 16S rRNA gene by MiSEQ sequencing allowed to identify 182 Operational Taxonomic Units. The community was dominated by Pseudomonadota, Bacteroidota, “Desulfobacterota” and Acidobacteriota (27, 21, 19 and 16%, respectively). Different culture conditions were used focusing on the isolation of anaerobic bacteria, including sulfate-reducing bacteria (SRB) and arsenate-reducing bacteria (ARB). Finally, 16 strains were isolated. Among them, 12 were phylogenetically identified, with two strains being SRB, belonging to the genus Solidesulfovibrio (“Desulfobacterota”), while ten are ARB belonging to the genera Azospira (Pseudomonadota), Peribacillus (Bacillota), Raineyella and Propionicimonas (Actinomycetota). The isolate representative of Raineyella genus probably corresponds to a new species, which, besides arsenate, also reduces nitrate, nitrite, and fumarate

The bacterial diversity on steam vents from Paricutín and Sapichu volcanoes

International audienceVapor steam vents are prevailing structures on geothermal sites in which local geochemical conditions allow the development of extremophilic microorganisms. We describe the structure of the prokaryotic community able to grow on the walls and rocks of such microecosystems in two terrestrial Mexican volcanoes: Paricutín (PI and PII samples) and its satellite Sapichu (S sample). The investigated samples showed similar diversity indices, with few dominant OTUs (abundance > 1%): 21, 16 and 23, respectively for PI, PII and S. However, each steam vent showed a particular community profile: PI was dominated by photosynthetic bacteria (Cyanobacteria and Chloroflexia class), PII by Actinobacteria and Proteobacteria, and S by Ktedonobacteria class, Acidobacteria and Cyanobacteria phyla. Concerning the predicted metabolic potential, we found a dominance of cellular pathways, especially the ones for energy generation with metabolisms for sulfur respiration, nitrogen fixation, methanogenesis, carbon fixation, photosynthesis, and metals, among others. We suggest a different maturity stage for the three studied fumaroles, from the youngest (PI) to the oldest (S and PII), also influenced by the temperature and other geochemical parameters. Furthermore, four anaerobic strains were isolated, belonging to Clostridia class (Clostridium sphenoides, C. swellfunanium and Anaerocolumna cellulosilytica) and to Bacilli class (Paenibacillus azoreducens)