A major concern among the environmental agencies includes the emission of sulfurous gas into the environment. Consequently, the oil agencies are in constant search of alternative processes aiming the reduction of sulfur content in fuels. One of the technologies commonly used is the hydrodesulfurization (HDS), but this is a high-cost process that also requires high temperature and pressure. A complementary alternative to HDS is biodesulfurization (BDS) involving the use of specific microorganisms to the removal of sulfur present in the carbon chain, using the oxidation pathway ''4S'', in which there is cleavage of carbon-sulfur bond, and maintaining the calorific value of the organic molecule. The BDS is a low-cost technique when compared with HDS. For this process to occur, activation of specific enzymes is needed, which is controlled by dszABC genes. Therefore, strategies to optimize this process have been of great importance to the oil refineries. For decades, attempts to try to implement BDS in the industry have been made, but difficulties in obtaining satisfactory results led the researchers to seek new knowledge about this bioprocess. The need of more studies concerning implementation on an industrial scale of this process is evident, since this biotechnology is a promising alternative to refineries in the near future.
The presence of sulphur in fossil fuels and the natural environment justifies the study of sulphur-utilising bacterial species and genes involved in the biodesulphurisation process. Technology has been developed based on the natural ability of microorganisms to remove sulphur from polycyclic aromatic hydrocarbon chains. This biotechnology aims to minimise the emission of sulphur oxides into the atmosphere during combustion and prevent the formation of acid rain. In this study, the isolation and characterization of desulphurising microorganisms in rhizosphere and bulk soil samples from Antarctica that were either contaminated with oil or uncontaminated was described. The growth of selected isolates and their capacity to utilise sulphur based on the formation of the terminal product of desulphurisation via the 4S pathway, 2-hydroxybiphenyl, was analysed. DNA was extracted from the isolates and BOX-PCR and DNA sequencing were performed to obtain a genomic diversity profile of cultivable desulphurising bacterial species. Fifty isolates were obtained showing the ability of utilising dibenzothiophene as a substrate and sulphur source for maintenance and growth when plated on selective media. However, only seven genetically diverse isolates tested positive for sulphur removal using the Gibbs assay. DNA sequencing revealed that these isolates were related to the genera Acinetobacter and Pseudomonas.
O presente trabalho apresenta uma reflexão acerca da temática da autonomia escolar dos sujeitos com Deficiência Intelectual, buscando ferramentas de intervenção para a promoção e a construção desta autonomia. Para tanto, consideramos as características da Deficiência Intelectual, questões pertinentes à aprendizagem escolar e autonomia. Deste modo, este artigo pode contribuir com educadores, psicopedagogos e gestores escolares que lidem com estudantes com Deficiência Intelectual.
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