Francielle Bücker

Effect of Environmental Variables on the Distribution of Two Freshwater Crabs (Anomura: Aeglidae)

Abstract We evaluate whether the abundance of the freshwater crabs Aegla itacolomiensis and A. platensis is related to any or all of 11 environmental variables. We sampled 205 Surber samples (33 × 33 cm) in a stream five meters wide in southern Brazil. For each Surber sample we obtained measures of flow velocity, depth, type of substrate, and availability of coarse particulate organic matter. The relationships between abundances of the two species and the environmental variables were assessed by regression trees. Only 2 of the 11 environmental variables were important in describing the abundances of the two species, both of them related to availability of coarse particulate organic matter. The abundance of Aegla itacolomiensis was related positively to quantity of fragmented leaves and, to a lesser degree, to quantity of twigs. For the abundance of A. platensis, quantity of twigs, followed by fragmented leaves, were the most important environmental factors. The quantity of recently fallen, unfragmented leaves was unimportant. We conclude that the two species of Aegla select locations with abundant old plant fragments that are usually colonized by fungi and bacteria. This conclusion is corroborated by previous studies indicating that Aegla spp. feed mostly on plant fragments.

Capability of a selected bacterial consortium for degrading diesel/biodiesel blends (B20): Enzyme and biosurfactant production

The search for alternative sources of energy, such as biodiesel, has been stimulated, since this biofuel is highly susceptible for biodegradation and has low toxicity, thus, reducing the impact in ecosystems. The objective of this study was to select a bacterial consortium with potential for degrading diesel/biodiesel blends (B20) obtained from areas contaminated with hydrocarbons/esters. In order to evaluate the biodegrability of the blend, six enzyme assays were conducted: alkane hydroxylase, Catechol 1,2-dioxygenase, Catechol 2,3-dioxygenase, Protocatechol 3,4-dioxygenase, ρ-NPA hydrolysis (esterase), and release of fatty acids through titration (lipase), with estimative of total protein and biosurfactant production (surface tension measurement and emulsifying index E24). The best results obtained allowed the selection of four bacteria isolates (Bacillus megaterium, Bacillus pumilus, Pseudomonas aeruginosa, and Stenotrophomonas maltophilia) for compiling a consortium, which will be used for bioaugmentation strategies in soils contaminated with these fuels. This consortium exhibited high potential for biodegradation of biodiesel, and might be an efficient alternative for cleaning up these contaminated environments.

Microbial growth in Acrocomia aculeata pulp oil, Jatropha curcas oil, and their respective biodiesels under simulated storage conditions

With increasing demands for biodiesel in Brazil, diverse oil feedstocks have been investigated for their potentials for biodiesel production. Due to the high biodegradability of natural oils and their respective biodiesels, microbial growths and consequent deterioration of final product quality are generally observed during storage. This study was aimed at evaluating the susceptibility of Acrocomia aculeata pulp oil and Jatropha curcas oil as well as their respective biodiesels to biodeterioration during a simulated storage period. The experiment was conducted in microcosms containing oil/biodiesel and an aqueous phase over 30 d. The levels of microbial contamination included biodiesel and oil as received, inoculated with fungi, and sterile. Samples were collected every 7 d to measure pH, surface tension, acidity index, and microbial biomass. The initial and final ester contents of the biodiesels were also determined by gas chromatography. The major microbial biomass was detected in A. aculeata pulp and J. curcas biodiesels. Significant reductions in pH values were observed for treatments with A. aculeata pulp biodiesel as a carbon source (p <0.05). The surface tension values decreased for all treatments (p <0.05). Total ester contents were decreased in A. aculeata pulp and J. curcas biodiesels when inoculated by fungi by approximately 8 and 12%, respectively, indicating the occurrence of biodegradation during the relatively short storage period of only 30 d.

Identification of Paenibacillus as a Symbiont in Acanthamoeba.

Amoebae of the genus Acanthamoeba occur worldwide and in addition to being pathogens, are important vehicles for microorganisms with clinical and environmental importance. This study aimed to evaluate the profiling of endosymbionts in 12 isolates of Acanthamoeba using V3 region of 16S rDNA denaturing gradient gel electrophoresis (DGGE) and sequencing. The DGGE enabled us to characterize the endosymbionts diversity in isolates of Acanthamoeba, and to identify Paenibacillus sp., an emerging pathogen, as an amoebic endosymbiont. The results of this study demonstrated that Acanthamoeba is capable of transporting a large number of endosymbionts. This is the first study that reports, the presence of Paenibacillus sp. as amebic symbiont.