Diversity of retrievable heterotrophic bacteria in Kongsfjorden, an Arctic fjord

Abstract The diversity and abundance of retrievable pelagic heterotrophic bacteria in Kongsfjorden, an Arctic fjord, was studied during the summer of 2011 (June, August, and September). Retrievable bacterial load ranged from 103 to 107 CFU L−1 in June, while it was 104-106 CFU L−1 in August and September. Based on 16S rRNA gene sequence similarities, a higher number of phylotypes was observed during August (22 phylotypes) compared to that during June (6 phylotypes) and September (12 phylotypes). The groups were classified into four phyla: Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes. Bacteroidetes was represented only by a single member Leewenhoekiella aequorea during the three months and was dominant (40%) in June. However, this dominance changed in August to a well-known phytopathogenic species Rhodococcus fascians (32%), which could be a result of decrease in the phytoplankton biomass following the secondary bloom. It is the first report of Halomonas titanicae isolation from the Arctic waters. It showed an increase in its abundance with the intrusion of Atlantic water into Kongsfjorden. Increased abundance of Psychrobacter species in the late summer months coincided with the presence of cooler waters. Thus, the composition and function of heterotrophic bacterial community was fundamentally different in different months. This could be linked to the changes in the water masses and/or phytoplankton bloom dynamics occurring in Arctic summer.

Yearly variation of bacterial production in the Arraial do Cabo protection area (Cabo Frio upwelling region): an evidence of anthropogenic pressure

Arraial do Cabo is where upwelling occurs more intensively on the Brazilian coast. Although it is a protection area it suffers anthropogenic pressure such as harbor activities and sporadic sewage emissions. Short-time studies showed a high variability of bacterial production (BP) in this region but none of them evaluated BP during long periods in a large spatial scale including stations under different natural (upwelling and cold fronts) and anthropogenic pressures. During 2006, we sampled surface waters 10 times (5 in upwelling and 5 in subsidence periods) in 8 stations and we measured BP, temperature as well as the concentrations of inorganic nutrients, pigments and particulate organic matter (POM). BP was up to 400 times higher when sewage emissions were observed visually and it had a positive correlation with ammonia concentrations. Therefore, in 2007, we did two samples (each during upwelling and subsidence periods) during sewage emissions in five stations under different anthropogenic pressure and we also measured particles abundance by flow cytometry. The 12 samples in the most impacted area confirmed that BP was highest when ammonia was higher than 2 μM, also reporting the highest concentrations of chlorophyll a and suspended particles. However, considering all measured variables, upwelling was the main disturbing factor but the pressure of fronts should not be neglected since it had consequences in the auto-heterotrophic coupling, increasing the concentrations of non fluorescent particles and POM. Stations clustered in function of natural and anthropogenic pressures degrees and both determined the temporal-spatial variability.

Flagellate protist abundance in phytotelmata of Aechmea distichantha Lem. (Bromeliaceae) in the upper Paraná river basin / Abundância de protozoários flagelados em fitotelmata de Aechmea distichantha Lem. (Bromeliaceae) na bacia do alto rio Paraná

In some Bromeliaceae species the leaf sheaths form a tank or phytotelma, accumulating water and organic detritus, conditions that allow the establishment of different communities. Thus, this study evaluated the relationship between diameter and volume of water in the tank of the bromeliad Aechmea distichantha Lem. and density of flagellates found in the phytotelmata, as well as the influence of the hydrological periods and proximity of sampled strata on the phytotelma patterns of abundance distribution. Samplings were conducted in two hydrological periods in 2010. In each sampling, four plants were collected from three different strata, classified according to the distance from the river level. A one-way ANOVA identified significant differences in flagellate density between hydrological periods. The influence of the water volume in the phytotelmata on the flagellate density was evidenced by regression analyses, as well as the lack of relationship between the density and perimeter of the tank. Moreover, the distance of the strata from the river level did not influence the pattern of flagellate abundance. Thus, our results suggested that the hydrological period and the volume of water in the tanks of Aechmea distichantha are determinant on the abundance of heterotrophic flagellate in the phytotelmata.

Em algumas Bromeliaceae as bainhas foliares formam uma cisterna ou fitotelma, onde ocorre acúmulo de água e detritos orgânicos, que permitem o estabelecimento de diferentes comunidades. Assim, este estudo avaliou a relação entre o diâmetro e volume de água no tanque de Aechmea distichantha Lem. e a abundância de flagelados encontrados nestes fitotelmata, bem como a influência do período hidrológico e a proximidade dos estratos amostrados sobre os padrões de distribuição desse atributo. As coletas foram realizadas em dois períodos hidrológicos no ano de 2010. Foram coletadas quatro plantas em três estratos diferentes de acordo com a distância em relação ao rio. Foram identificadas diferenças significativas entre a densidade dos flagelados e os períodos hidrológicos. Além disso, verificou-se a influência do volume de água presente nos fitotelmata sobre a densidade dos flagelados, bem como a ausência de relação entre a densidade desses protistas e o perímetro do tanque das bromélias. A distância dos distintos estratos em relação ao rio não influenciou a abundância dos flagelados. Assim, os resultados sugerem que o período hidrológico bem como o volume de água presente nos tanques de Aechmea distichantha atuam como um fator determinante sobre a abundância da comunidade de flagelados heterotróficos nos fitotelmata.

Growth of aphanothece microscopica nägeli on exogenous sugars / Cultivo da aphanothece microscopica nägeli a partir de açúcares

Biological processes for wastewater treatment generally produce biomass or active sludge without reuse. In this context, incorporation of organic matter and nutrients from agro industrial effluents into cell mass for single-cell protein allowed application of sustainable process. Cyanobacteria could be used due to its versatile metabolism. So, the aim of this paper was evaluate the growth of cyanobacteria Aphanothece microscopica Nägeli growth on heterotrophic medium with glucose, lactose and sucrose. Growth curves indicated that cultivation of cyanobacterial on the dark depend the type of carbon source and there are different mechanisms for glucose, fructose and sucrose consumption. Results suggest a useful application of cyanobacteria on organic matter removal from wastewater.

Os processos biológicos de tratamento de águas residuárias produzem grandes quantidades de biomassa geralmente sem utilização posterior. Neste contexto, a incorporação de matéria orgânica e nutrientes de efluentes agroindustriais em células microbianas visando a produção de proteínas unicelulares corresponderia a um processo sustentável. Nesse sentido, as cianobactérias poderiam ser aplicadas devido ao seu metabolismo versátil. Sendo assim, o trabalho teve como objetivo avaliar o cultivo heterotrófico da cianobactéria Aphanothece microscopica Nägeli em meios contendo glicose, lactose e sacarose. As curvas de crescimento indicaram que o cultivo heterotrófico depende do tipo de fonte de carbono, sugerindo diferentes mecanismos de incorporação e consumo da glicose, lactose sacarose. Os resultados indicam uma possível aplicação desta cianobactéria na remoção destas moléculas orgânicas em águas residuárias.

Q10 of heterotrophic activity during aerobic decomposition of Utricularia breviscapa and its effect on carbon cycling in a tropical lagoon / Q10 da atividade heterotrófica durante a decomposição aeróbia de Utricularia breviscapa e seu efeito na ciclagem do carbono da lagoa do óleo

In this study the Q10 coefficients of heterotrophic activities were measured during aerobic decomposition of Utricularia breviscapa Wright ex Griseb from Óleo lagoon (21° 36' S and 49° 47' W), Luiz Antonio, SP. The bioassays were set up with fragments of U. breviscapa and incubated with lagoon water at distinct temperatures (15.3, 20.8, 25.7 and 30.3 °C). Periodically for 95 days, the concentrations of dissolved oxygen were determined in the bioassays. The results of the temporal variation of dissolved oxygen were fitted to a first-order kinetic model. The stoichiometric relations were calculated on the basis of these fittings. In general, the results allowed us to conclude: i) the oxygen/carbon stoichiometric relations (O/C) varied in function of temperature and time. The temporal variations of the O/C observed in the decomposition of U. breviscapa, suggest that, in the initial phases of the process, low organic carbon concentrations were enough to generate great demands of oxygen, ii) the oxygen consumption coefficients (k d) presented low variation in function of increasing temperature, iii) the increment of the temperature induced a higher consumption of oxygen (COmax) and iv) the simulations indicate that during summer, temperature activates the metabolism of decomposing microbiota.

Neste estudo, foram discutidos os coeficientes Q10 das atividades heterotróficas durante a decomposição aeróbia de Utricularia breviscapa Wright ex Griseb da lagoa do Óleo (21° 36' S e 47° 49' O), Luiz Antônio, SP. Os bioensaios foram realizados com fragmentos de U. breviscapa e água da lagoa sendo incubados em diferentes temperaturas (15,3, 20,8, 25,7 e 30,3 °C). Periodicamente, por 95 dias, as concentrações de oxigênio dissolvido foram determinadas nos bioensaios. Os resultados da variação temporal de oxigênio dissolvido foram ajustados a um modelo cinético de primeira ordem. As relações estequiométricas foram calculadas com base nesses ajustes. De modo geral, os resultados permitiram concluir: i) as relações estequiométricas (O/C) variaram em função da temperatura e do tempo. As variações temporais dos coeficientes estequiométricos observadas na decomposição de U. breviscapa sugerem que, nas fases iniciais do processo, concentrações baixas de carbono orgânico são suficientes para gerar grandes demandas de oxigênio; ii) os coeficientes de consumo de oxigênio (k d) apresentaram baixa variação em função do incremento da temperatura; iii) o incremento da temperatura induziu um maior consumo de oxigênio (COmáx); e iv) as simulações indicaram que, durante o verão, a temperatura favoreceu o aumento do metabolismo da microbiota decompositora.