Bioprospecção de estirpes bacterianas com capacidade de dessulfurização em amostras de solo e sedimentos do Continente Antártico.

A presença natural do enxofre no meio ambiente e nos combustíveis fósseis justifica a ocorrência tanto de espécies bacterianas, quanto de genes específicos, associados ao processo de biodessulfurização. Esta tecnologia, baseada no metabolismo dos microrganismos, consiste na retirada do enxofre presente nas cadeias dos hidrocarbonetos aromáticos policíclicos (PAH’s), visando minimizar as emissões de óxidos sulfurosos na atmosfera, no processo de refino, além de evitar a formação e precipitação da chuva ácida no meio ambiente. Este trabalho teve como objetivo investigar a presença dos microrganismos dessulfurizadores, a partir de amostras de solos rizosféricos e não-rizosféricos, contaminados com petróleo e não-contaminados e em solos oligotróficos coletadas no Continente Antártico. Para isso, foram obtidos isolados bacterianos os quais foram submetidos a testes de capacidade de dessulfurização, em função da formação do produto final do metabolismo microbiano, o 2-hidroxibifenil, evidenciando a cinética do processo de dessulfurização do dibenzotiofeno através de técnicas espectrofotométricas. Além disso, também foram utilizadas técnicas moleculares de extração de DNA, BOX-PCR e sequenciamento de DNA, no intuito de se obter um perfil genômico e filogenético da comunidade microbiana cultivável presente nestas amostras. Deste modo, foram obtidos 50 isolados com capacidade de utilizar o dibenzotiofeno como fonte energética, independente da rota metabólica, sendo que a maioria apresentou forma de cocos (68%) com coloração Gram-positiva (44%). Após a seleção dos isolados, através do ensaio de Gibb’s, obteve-se 7 isolados com metabolismo de dessulfurização, sendo que a partir da curva de crescimento, em função da formação do 2-hidroxibifenil, verificou-se que uma estirpe possuía altos índices de dessulfurização, em relação aos demais isolados. O sequenciamento revelou que os 7 isolados pertencem aos gêneros Acinetobacter sp., Pseudomonas sp., e à espécie Pseudomonas corrugata.The presence of sulfur in nthe natural environment and fossil fuels justifies the occurrence of both species, and specific genes involved in the process of biodesulfurization. This technology, based on the metabolism of microorganisms, consists of removing the sulfur present in chains of polycyclic aromatic hydrocarbons (PAH's) to minimize emissions of sulfur oxides in the atmosphere, in the refining, and prevent the formation and precipitation of acid rain in the environment. This work aimed to investigate the occurence the microorganisms with desulfurization ability, from samples of soil collected from the Antarctic Continent. For this reason was tested the growth of selected isolates with desulfurization capacity, due to the formation of the end product of microbial metabolism, 2-hydroxibifenyl, showing the kinetics of the desulfurization process of dibenzothiophene by spectrophotometric techniques. In addition, molecular techniques were used for DNA extraction, BOX-PCR and DNA sequencing in order to obtain a profile of genomic and phylogenetic culturable microbial community present in these samples. Thus, was obtained 50 isolates with the ability to use dibenzothiophene as an energy source, most of which had the form of cocci (68%) with Gram-positive cell wall (44%). After the selection of isolates, by testing Gibb's, obtained a 7 isolates with desulfurization metabolism, and the growth curve, due to the formation of 2-hydroxybiphenyl showed only a strain with high levels of desulfurization, for other strains. The sequencing revealed that the 7 isolates belong to the genus Acinetobacter sp., Pseudomonas sp., and the species Pseudomonas corrugata

Characterization of bacterial strains capable of desulphurisation in soil and sediment samples from Antarctica.

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

Occurrence of Aspergillus niger strains on a polychrome cotton painting and their elimination by anoxic treatment

This study aimed to isolate and identify the population of filamentous fungi colonizing a cotton painting, whose conservation status was compromised and showed signs of biodeterioration due to dirt accumulation and microbial metabolism. In addition, microbiological techniques such as cultivation-dependent approach and molecular biology were used to identify microbial populations and to eliminate their metabolic action. For this, the nondestructive anoxic atmosphere technique was used, in which the microbial metabolism was affected by the absence of oxygen. Prior to exposure to an anoxic atmosphere, only one fungal species, Aspergillus niger, was identified at 12 points sampled in the obverse and reverse of the artwork; no fungal species persisted as a result of anoxic treatment. These results showed that exposure to anoxic conditions was effective for the total elimination of isolated fungal strains as well as their spores. In conclusion, this study proved the unprecedented effectiveness of a nondestructive technique for artwork on textile colonized by black fungi species. Thus, this interdisciplinary work involving conservation, microbiology, and chemistry presents a tool to eliminate microorganisms, while maintaining the integrity of artwork and safety of the restorer, that can be applied prior to artwork restoration.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author