Isis Serrano Silva

Bioremediation of a polyaromatic hydrocarbon contaminated soil by native soil microbiota and bioaugmentation with isolated microbial consortia

Biodegradation of a mixture of PAHs was assessed in forest soil microcosms performed either without or with bioaugmentation using individual fungi and bacterial and a fungal consortia. Respiratory activity, metabolic intermediates and extent of PAH degradation were determined. In all microcosms the low molecular weight PAHs naphthalene, phenanthrene and anthracene, showed a rapid initial rate of removal. However, bioaugmentation did not significantly affect the biodegradation efficiency for these compounds. Significantly slower degradation rates were demonstrated for the high molecular weight PAHs pyrene, benz[a]anthracene and benz[a]pyrene. Bioaugmentation did not improve the rate or extent of PAH degradation, except in the case of Aspergillus sp. Respiratory activity was determined by CO(2) evolution and correlated roughly with the rate and timing of PAH removal. This indicated that the PAHs were being used as an energy source. The native microbiota responded rapidly to the addition of the PAHs and demonstrated the ability to degrade all of the PAHs added to the soil, indicating their ability to remediate PAH-contaminated soils.

Purification and structural characterization of fengycin homologues produced by Bacillus subtilis LSFM-05 grown on raw glycerol.

Raw glycerol is a byproduct of biodiesel production that currently has low to negative value for biodiesel producers. One option for increasing the value of raw glycerol is to use it as a feedstock for microbial production. Bacillus subtilis LSFM 05 was used for the production of fengycin in a mineral medium containing raw glycerol as the sole carbon source. Fengycin was isolated by acid precipitation at pH 2 and purified by silica gel column chromatography and characterized using electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) with collision-induced dissociation (CID). The mass spectrum revealed the presence of the ions of m/z 1,435.7, 1,449.9, 1,463.8, 1,477.8, 1,491.8 and 1,505.8, which were further fragmented by ESI-MS/MS. The CID profile showed the presence of a series of ions (m/z 1,080 and 966) and (m/z 1,108 and 994) that represented the different fengycin homologues A and B, respectively. Fengycin homologues A and B are variants that differ at position 6 of the peptide moiety, having either Ala or Val residues, respectively. Mass spectrometry analyses identified four fengycin A and three fengycin B variants with fatty acid components containing 14–17 carbons. These results demonstrate that raw glycerol can be used as feedstock to produce fengycin, and additional work should focus on the optimization of process conditions to increase productivity.

Degradation of lignosulfonic and tannic acids by ligninolytic soil fungi cultivated under icroaerobic conditions

Fungos isolados de solo foram avaliados quanto a habilidade em degradarem compostos derivados de lignina pela producao de enzimas ligninoliticas. Os acidos lignosulfonicos e tânico foram usados separadamente como unica fonte de carobono para cultivo dos fungos em 30 dias sob condicoes microaerobias. Os fungos foram capazes de crescer e usar tais compostos como fonte de carbono e mostraram producao de lignina-peroxidase, manganes-peroxidase e lacase. Degradacoes expressivas dos acidos lignosulfonico e tânico foram verificadas por Cromatografia Liquida de Alta Eficiencia (CLAE), indicando grande potencial de uso em processos de biorremediacao de macromoleculas aromaticas similares a lignina em ambientes naturais sob condicoes baixas de oxigenacao.

Sugarcane bagasse: Source for the production of ligninocelullolytic enzymes

A producao de enzimas lignoceluloliticas atraves de Pleurotus ssp foi estudada em fermentacao submersa utilizando bagaco de cana. Entre estas enzimas, lacase e manganes peroxidase foram detectadas. Os maiores produtores de lacase foram as linhagem Pleurotus sp BCCB068, com 6,23 U/L no 15o dia e a linhagem Pleurotus sajor-caju, com 3,52 U/L no 10o dia de incubacao. Manganes peroxidase foi detectada com Pleurotus sp BCCB068 (31.56 U/L) no 5o dia e 23,58 U/L com Pleurotus tailandia no 15o dia de incubacao. A producao de enzimas celuloliticas nao foi significativa. Estes resultados mostram que o residuo de bagaco de cana e uma possivel fonte de enzimas ligninoliticas e possui aplicabilidade na area biotecnologica. Palavras-chave: biodegradacao, enzimas, reciclagem.

BIODEGRADATION OF CARBOXYMETHYLCELLULOSE USING PLEUROTUS : OLIGOSACCHARIDES PRODUCTION AND FERMENTABLE SUGARS FOR ETHANOL INDUSTRY

In this present study, white-rot fungi Pleurotus sp BCCB068 were evaluated as regards the degradation of the cellulose matrix with production of enzymes using submerged fermentation.The crude extract obtained from the fungi growths was used as enzyme source for carboxymethylcellulose hydrolysis, reached 54.8% of degradation during 0-60 minutes of reaction period, with formation of oligosaccharides, as well as several sugar monomers (cellobiose, mannose, maltose, fructose and glucose). These results indicate great potential of these fungal strains to degrade cellulosic materials and produce sugar monomers to be used in ethanol industries.