Nutrient availability in tropical caves influences the dynamics of microbial biomass.

Few studies have evaluated the trophic level in tropical caves, and none related the microbial biomass dynamics in the immobilization of carbon and nitrogen. Here, four tropical caves of Terra Ronca State Park, Brazil, were studied: Angélica, São Bernardo, Terra Ronca I, and Terra Ronca II caves. Physical, chemical, and microbiological parameters (microbial biomass and respiration) were estimated in the dry and wet seasons. São Bernardo, Terra Ronca I, and Terra Ronca II caves presented higher nitrogen and microbial biomass nitrogen (MBN) values in the wet season than in the dry season. On the other hand, the Angélica cave showed larger amounts of nitrogen and lower MBN values in the dry season. These results indicate that caves can be adjusted in two ecological theories known as "stoichiometric decomposition" and "microbial nitrogen mining"-to the effects of nutrient availability on organic matter decomposition. The caves studied showed different environmental dynamics in relation to organic matter decomposition, which allows them to be considered unique and possess specific characteristics. Microbial biomass dynamics can be an important parameter to evaluate the availability of nutrients and ecological dynamics of the trophic network in subterranean environments.

Biotransformation of methylphenylacetonitriles by Brazilian marine fungal strain Aspergillus sydowii CBMAI 934: eco-friendly reactions.

This study reports the biotransformation of methylphenylacetonitriles by Brazilian marine filamentous fungus Aspergillus sydowii CBMAI 934 under eco-friendly reaction conditions. The phenylacetonitrile 1, 2-methylphenylacetonitrile 2, 3-methylphenylacetonitrile 3, and 4-methylphenylacetonitrile 4 were quantitatively biotransformed into 2-hydroxyphenylacetic 1a, 2-methylphenylacetic acid 2a, 3-methylphenylacetic acid 3a, and 4-methylphenylacetic acid 4a by enzymatic processes using whole cell as biocatalyst. The marine fungus A. sydowii CBMAI 934 is thus a promising biocatalyst for the preparation of important carboxylic acids under mild conditions (pH 7.5 and 32 °C) from nitrile compounds.

Protozooplankton and its relationship with environmental conditions in 13 water bodies of the Mogi-Guacu basin - SP, Brazil

Protozooplankton is an important component of the aquatic microbial food webs and its composition, density, and distribution reflect the chemical, physical, and biological aspects of the environment. Considering the scarce literature on freshwater protozoans in Brazil and on protozoan ecology in subtropical environments, we listed the ciliates and amoebae taxa found in 13 water bodies in São Paulo State and analyzed their abundance in relation to the environmental variables. We collected two samples in each environment, fixed immediately with mercuric chloride and stained with bromophenol blue. After microscopical analysis, 74 protozoan genera were identified and the Ciliophora were dominant in the majority of the environments. The Stichotrichia, represented mostly by the genus Halteria, occurred in all environments, and was the dominant subclass in five of them. The canonic correspondence analysis of the most frequent genera and the environmental variables showed that nitrite and nitrate were the variables that better explained the distribution of Limnostrombidium, Urotricha, and Vorticella. The densities of the genera Halteria, Coleps, and of the species Cinetochilum margaritaceum were positively affected by increasing concentrations of dissolved oxygen, particulate phosphate, conductivity, and temperature. C. margaritaceum were also negatively affected by increasing concentrations of nitrite and nitrate. Considering that we made only one sampling in each environment, the richness was high compared to the mean diversity of lakes in the São Paulo State. The Diogo Lake, located in an ecological reserve, was the richest one, confirming the need of more research on the biodiversity of more preserved environments.

O protozooplâncton é um componente importante da rede trófica microbiana de ambientes aquáticos e sua composição, densidade e distribuição refletem os aspectos físicos, químicos e bióticos do ambiente. Considerando a escassa literatura sobre protozoários de água doce no Brasil e sobre sua ecologia em ambientes subtropicais, inventariamos os táxons de ciliados e amebas em 13 corpos d'água do Estado de São Paulo e analisamos a variação na abundância dos gêneros/espécies de maior incidência em relação às variáveis ambientais. Coletamos duas amostras por ambiente, fixando-as com cloreto de mercúrio e corando-as com azul de bromofenol para posterior quantificação e identificação em microscópio ótico. Identificamos 74 gêneros de ciliados e amebas, e os Ciliophora dominaram na maioria dos ambientes. A subclasse Stichotrichia ocorreu em todos os ambientes, predominando em cinco deles, especialmente pela ocorrência o gênero Halteria. A Análise de Correspondência Canônica mostrou que as concentrações de nitrito e nitrato são as principais variáveis que explicam a distribuição dos gêneros Limnostrombidium, Urotricha e Vorticella. O aumento na concentração de oxigênio dissolvido, condutividade, temperatura e concentração de fosfato particulado afetou positivamente a densidade dos gêneros Halteria e Coleps e da espécie Cinetochilum margaritaceum, que foi ainda influenciada negativamente pelo aumento nas concentrações de nitrito e nitrato. Considerando-se que foi realizada apenas uma coleta, a riqueza de espécies foi alta quando comparada à média de taxa encontrada para corpos d'água do Estado de São Paulo. O ambiente mais rico, Lagoa do Diogo, localiza-se em uma estação ecológica, confirmando a necessidade de mais pesquisas sobre a diversidade em ambientes menos impactados.

Biotransformation of phenylacetonitrile to 2-hydroxyphenylacetic acid by marine fungi.

Marine fungi belonging to the genera Aspergillus, Penicillium, Cladosporium, and Bionectria catalyzed the biotransformation of phenylacetonitrile to 2-hydroxyphenylacetic acid. Eight marine fungi, selected and cultured with phenylacetonitrile in liquid mineral medium, catalyzed it quantitative biotransformation to 2-hydroxyphenylacetic acid. In this study, the nitrile group was firstly hydrolysed, and then, the aromatic ring was hydroxylated, producing 2-hydroxyphenylacetic acid with 51 % yield isolated. In addition, the 4-fluorophenylacetonitrile was exclusively biotransformed to 4-fluorophenylacetic acid by Aspergillus sydowii Ce19 (yield = 51 %). The enzymatic biotransformation of nitriles is not trivial, and here, we describe an efficient method for production of phenylacetic acids in mild conditions.

Isolation of Brazilian marine fungi capable of growing on DDD pesticide.

The fungi Aspergillus sydowii Ce15, Aspergillus sydowii Ce19, Aspergillus sydowii Gc12, Bionectria sp. Ce5, Penicillium miczynskii Gc5, Penicillium raistrickii Ce16 and Trichoderma sp. Gc1, isolated from marine sponges Geodia corticostylifera and Chelonaplysylla erecta, were evaluated for their ability to grow in the presence of DDD pesticide. Increasing concentrations of DDD pesticide, i.e., 5.0 mg (1.56 × 10⁻¹² mmol), 10.0 mg (3.12 × 10⁻²) mmol) and 15.0 mg (4.68 × 10⁻² mmol) in solid and liquid culture media were tested. The fungi Trichoderma sp. Gc1 and Penicillium miczynskii Gc5 were able to grow in the presence of up to 15.0 mg of DDD, suggesting their potential for biodegradation. A 100% degradation of DDD was attained in liquid culture medium when Trichoderma sp. Gc1 was previously cultivated for 5 days and supplemented with 5.0 mg of DDD in the presence of hydrogen peroxide. However, the quantitative analysis showed that DDD was accumulated on mycelium and biodegradation level reached a maximum value of 58% after 14 days.

Dynamics of fipronil in Oleo Lagoon in Jataí Ecological Station, São Paulo-Brazil.

Fipronil is a phenylpyrazole pesticide widely used to protect sugar-cane crops from insect pests. After reaching the environment, this insecticide may have several fates. This research aimed to propose a kinetic model to describe the fate of commercial fipronil Regent 800WG in the sediment-water interface of the Oleo Lagoon in the Mogi-Guaçu river floodplain, situated within the Jataí Ecological Station, by means of a microcosm scale experiment. Results showed that a small fraction of the pesticide is quickly dragged to the sediment while most of it remains in the water column. Biodegradation proves to be an important fipronil degradation route, especially when microorganisms capable of using fipronil as sole carbon source increase their population, as a function of exposure time. Biodegradation rates were higher in the sediment than in the water column.

Biotransformation of α-bromoacetophenones by the marine fungus Aspergillus sydowii.

The biotransformation reactions of α-bromoacetophenone (1), p-bromo-α-bromoacetophenone (2), and p-nitro-α-bromoacetophenone (3) by whole cells of the marine fungus Aspergillus sydowii Ce19 have been investigated. Fungal cells that had been grown in artificial sea water medium containing a high concentration of chloride ions (1.20 M) catalysed the biotransformation of 1 to 2-bromo-1-phenylethanol 4 (56%), together with the α-chlorohydrin 7 (9%), 1-phenylethan-1,2-diol 9 (26%), acetophenone 10 (4%) and phenylethanol 11 (5%) identified by GC-MS analysis. In addition, it was observed that the enzymatic reaction was accompanied by the spontaneous debromination of 1 to yield α-chloroacetophenone 5 (9%) and α-hydroxyacetophenone 6 (18%) identified by GC-FID analysis. When 2 and 3 were employed as substrates, various biotransformation products were detected but the formation of halohydrins was not observed. It is concluded that marine fungus A. sydowii Ce19 presents potential for the biotransformations of bromoacetophenone derivatives.