Preliminary notes on yeasts associated with necrotic cactus stems from different localities in Brazil

As leveduras encontradas em cladódios necrosados de três cactos colunares (Pilosocereus machrisii, Pilosocereus vilaboensis and Praecereus euchlorus) em oito localidades no Brasil foram identificadas e uma análise de similaridade baseada na distância Sorensen foi usada para comparar as comunidades nas diferentes localidades. Dos 56 cladódios necrosados amostrados, 32 produziram colônias de leveduras. Dez espécies de leveduras foram identificadas a partir de 53 isolados, com as espécies Pichia cactophila, Candida sonorensis, Geotrichum sp. e Sporopachydermia cereana sendo as mais comuns. As espécies restantes ocorreram em baixas freqüências. O dendograma (UPGMA) construído a partir da análise de similaridade agrupou comunidades de leveduras obtidas em diferentes espécies de cactos e indicou que as espécies de cactos hospedeiros não foram determinantes nesse agrupamento.

Formaldehyde degradation in an anaerobic packed-bed bioreactor.

The development of appropriate technologies for the treatment of formaldehyde discharged into the environment is important to minimize its impact. Aerobic systems have been employed, although alternative anaerobic treatments have also been widely studied, mainly due to their low energy consumption and sludge production. However, toxic substances can lead to disturbances in anaerobic reactors. Some research has already been developed on formaldehyde anaerobic biological treatment, but no consensus has yet been reached about its behavior nor has the most efficient system been identified. Aiming at finding supporting evidence for this issue, therefore, this study investigated the degradation and toxicity of formaldehyde in a Horizontal-Flow Anaerobic Immobilized Sludge Reactor. Formaldehyde concentrations of 26.2-1158.6 mg HCHO/L were applied in the reactor, resulting in formaldehyde and chemical oxygen demand removal efficiencies of 99.7% and 92%, respectively. Volatile fatty acids with up to five carbons, found during the degradation of formaldehyde, are believed to indicate that the degradation followed routes unlike those suggested in the literature, which reports the formation of intermediates such as methanol and formic acid. The Monod kinetic model adhered to the experimental data well, with apparent kinetic parameters estimated as r(app)max) = 2.79 x 10(-3) mg HCHO/mg SSVh and K (app)(s) = 242.8 mg HCHO/L.

Relationships between necrotic cactus availability and population size in a cactophilic Drosophila (Diptera, Drosophilidae) located on a sandstone table hill in Brazil

Drosophila gouveai is a cactophilic species endemic to South America. In southeast Brazil it is found on summits of isolated hills, which apparently are current refugia resulting from climatic changes during the Quaternary Period. It breeds only in necrotic cactus cladodes of Pilosocereus machrisii. Temporal differences in necrotic cactus availability could have a great impact upon D. gouveai population size, and could thus influence its evolutionary history. We analyzed the relationship between necrotic cactus availability and population size of D. gouveai. The fluctuation in the population size, variation in necrotic cactus availability and exploitation of this resource by larvae were surveyed bimonthly for one year on a sandstone table hill in central-south Brazil. Temporal necrotic cactus availability did not vary significantly, though in June there was a moderate decrease Larval populations were highest in October and December. The D. gouveai population size was highest in February and remained relatively stable the rest of the year. The observed fluctuation in population size was not a function of temporal necrotic cactus availability in quantitative terms.