Estudo da comunidade fitoplanctônica no reservatório do Carpina-PE, com ênfase em Cyanobacteria / Study of the phytoplankton community with emphasis on Cyanobacteria, in Carpina-PE reservoir

Florações de Cyanobacteria são freqüentemente encontradas em reservatórios utilizados para abastecimento público, em decorrência dos processos de eutrofização. No presente trabalho, foram realizadas oito coletas de água de julho a novembro de 2006, com o objetivo de estudar a dinâmica da comunidade fitoplanctônica com ênfase em Cyanobacteria, no reservatório do Carpina-PE. Para o levantamento florístico, foram coletadas amostras vivas e preservadas em formalina a 2%, utilizando-se rede de plâncton com abertura de malha de 25m. Para as análises quantitativas, as amostras foram coletadas com frascos de boca larga, preservadas com formalina (2%), e quantificadas em câmaras de Utermõhl de 5mL. As análises fitoplanctônicas foram realizadas em microscópio invertido. Foram identificados 21 táxons distribuídos entre as seguintes divisões: Cyanobacteria (10spp.), Chlorophyta(6spp.), Chrysophyta (4spp.) e Euglenophyta (1spp.). Destes, 71,43% apresentaram-se como muito freqüentes, destacando-se as Cyanobacteria, com as maiores abundâncias. Quanto à densidade dasCyanobacteria, todas as amostras apresentaram valores acima de 100.000 cel.mL-1. De acordo com a OMS, o ambiente encontra-se em nível de alerta 2, indicando um altíssimo risco à saúde pública.

Production and properties of the cellulase-free xylanase from Thermomyces lanuginosus IOC-4145

In recent years, xylanases have expanded their use in many processing industries, such as pulp and paper, food and textile. Thermomyces lanuginosus IOC-4145 was able to produce a very high level of cellulase-free xylanase in shaken cultures using corncob as substrate (500 U/ml). An optimization of the medium composition in submerged fermentation was carried out aiming at a low cost medium composition for enzyme production. Statistical experiment design ws employed for this purpose, pointing out corncob as the most important parameter, which affects enzyme production. Additionally, the influence of several chemicals on zulanase activity was investigated in the crude extract. A slight stimulation of the enzyme (5-15 percent) was achieved with NaCl and urea, both at 3 mM of concentration. On the other hand, dithiothreitol and ß-mercaptoethanol at a molarity of 5mM have caused a strong stimulation of the enzyme (40-53 percent). The crude xylanase displayed appreciable thermostability, retaining almost 50 percent of activity during 24 hours of incubation at 50oC; about 50 percent of activity was present at 60oC even after4 hours of incubation. The enzyme also exhibited good storage stability at û20oC without any stabilizing agent.

Extremely thermophilic microorganisms and their polymer-hydrolytic enzymes

Thermophilic and hyperthermophilic microorganisms are found as normal inhabitants of continental and submarine volcanic areas, geothermally heated sea-sediments and hydrothermal vents and thus are considered extremophiles. Several present or potential applications of extremophilic enzymes are reviewed, especially polymer-hydrolysing enzymes, such as amylolytic and hemicellulolytic enzymes. The purpose of this review is to present the range of morphological and metabolic features among those microorganisms growing from 70ºC to 100ºC and to indicate potential opportunities for useful applications derived from these features