RESUMO
Abstract The aerobic degradation of aromatic compounds by bacteria is performed by dioxygenases. To show some characteristic patterns of the dioxygenase genotype and its degradation specificities, twenty-nine gram-negative bacterial cultures were obtained from sediment contaminated with phenolic compounds in Wuhan, China. The isolates were phylogenetically diverse and belonged to 10 genera. All 29 gram-negative bacteria were able to utilize phenol, m-dihydroxybenzene and 2-hydroxybenzoic acid as the sole carbon sources, and members of the three primary genera Pseudomonas, Acinetobacter and Alcaligenes were able to grow in the presence of multiple monoaromatic compounds. PCR and DNA sequence analysis were used to detect dioxygenase genes coding for catechol 1,2-dioxygenase, catechol 2,3-dioxygenase and protocatechuate 3,4-dioxygenase. The results showed that there are 4 genotypes; most strains are either PNP (catechol 1,2-dioxygenase gene is positive, catechol 2,3-dioxygenase gene is negative, protocatechuate 3,4-dioxygenase gene is positive) or PNN (catechol 1,2-dioxygenase gene is positive, catechol 2,3-dioxygenase gene is negative, protocatechuate 3,4-dioxygenase gene is negative). The strains with two dioxygenase genes can usually grow on many more aromatic compounds than strains with one dioxygenase gene. Degradation experiments using a mixed culture representing four bacterial genotypes resulted in the rapid degradation of phenol. Determinations of substrate utilization and phenol degradation revealed their affiliations through dioxygenase genotype data.
Assuntos
Fenol/metabolismo , Dioxigenases/genética , Dioxigenases/metabolismo , Bactérias Gram-Negativas/enzimologia , Bactérias Gram-Negativas/metabolismo , Filogenia , Pseudomonas , Poluentes do Solo/metabolismo , Acinetobacter , DNA Bacteriano/genética , DNA Bacteriano/química , DNA Ribossômico/genética , DNA Ribossômico/química , Carbono/metabolismo , RNA Ribossômico 16S/genética , Biotransformação , Análise por Conglomerados , China , Reação em Cadeia da Polimerase , Análise de Sequência de DNA , Sedimentos Geológicos/microbiologia , Alcaligenes , Poluição Ambiental , Bactérias Gram-Negativas/classificação , Bactérias Gram-Negativas/genéticaRESUMO
The aerobic degradation of aromatic compounds by bacteria is performed by dioxygenases. To show some characteristic patterns of the dioxygenase genotype and its degradation specificities, twenty-nine gram-negative bacterial cultures were obtained from sediment contaminated with phenolic compounds in Wuhan, China. The isolates were phylogenetically diverse and belonged to 10 genera. All 29 gram-negative bacteria were able to utilize phenol, m-dihydroxybenzene and 2-hydroxybenzoic acid as the sole carbon sources, and members of the three primary genera Pseudomonas, Acinetobacter and Alcaligenes were able to grow in the presence of multiple monoaromatic compounds. PCR and DNA sequence analysis were used to detect dioxygenase genes coding for catechol 1,2-dioxygenase, catechol 2,3-dioxygenase and protocatechuate 3,4-dioxygenase. The results showed that there are 4 genotypes; most strains are either PNP (catechol 1,2-dioxygenase gene is positive, catechol 2,3-dioxygenase gene is negative, protocatechuate 3,4-dioxygenase gene is positive) or PNN (catechol 1,2-dioxygenase gene is positive, catechol 2,3-dioxygenase gene is negative, protocatechuate 3,4-dioxygenase gene is negative). The strains with two dioxygenase genes can usually grow on many more aromatic compounds than strains with one dioxygenase gene. Degradation experiments using a mixed culture representing four bacterial genotypes resulted in the rapid degradation of phenol. Determinations of substrate utilization and phenol degradation revealed their affiliations through dioxygenase genotype data.
Assuntos
Dioxigenases/genética , Dioxigenases/metabolismo , Bactérias Gram-Negativas/enzimologia , Bactérias Gram-Negativas/metabolismo , Fenol/metabolismo , Acinetobacter , Alcaligenes , Biotransformação , Carbono/metabolismo , China , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Poluição Ambiental , Sedimentos Geológicos/microbiologia , Bactérias Gram-Negativas/classificação , Bactérias Gram-Negativas/genética , Filogenia , Reação em Cadeia da Polimerase , Pseudomonas , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Poluentes do Solo/metabolismoRESUMO
Whey after acid protein precipitation was used as substrate for PHB production in orbital shaker using Alcaligenes latus. Statistical analysis determined the most appropriate hydroxide for pH neutralization of whey after protein precipitation among NH4OH, KOH and NaOH 10%w/v. The results were compared to those of commercial lactose. A scale-up test in a 4L bioreactor was done at 35°C, 750rpm, 7L/min air flow, and 6.5 pH. The PHB was characterized through Fourier Transform Infrared Spectroscopy, thermogravimetry and differential scanning calorimetry. NH4OH provided the best results for productivity (p), 0.11g/L.h, and for polymer yield, (YP/S), 1.08g/g. The bioreactor experiment resulted in lower p and YP/S. PHB showed maximum degradation temperature (291°C), melting temperature (169°C), and chemical properties similar to those of standard PHB. The use of whey as a substrate for PHB production did not affect significantly the final product quality.
Assuntos
Alcaligenes/metabolismo , Hidroxibutiratos/análise , Hidroxibutiratos/metabolismo , Lactose/metabolismo , Poliésteres/análise , Poliésteres/metabolismo , Proteínas do Soro do Leite/metabolismo , Ácido 3-Hidroxibutírico/metabolismo , Ácidos/química , Ácidos/farmacologia , Reatores Biológicos , Varredura Diferencial de Calorimetria , Precipitação Química/efeitos dos fármacos , Polímeros/metabolismo , Temperatura , Termogravimetria , Soro do Leite/química , Proteínas do Soro do Leite/químicaRESUMO
Biodegradation of tributyltin (TBT) by four tin resistant Gram negative bacteria isolated from extremely contaminated river sediments in the Atacama Desert in Chile was studied. Moraxella osloensis showed the greatest resistance and degradation capability of TBT, producing less toxic by-products, such as dibutyltin (DBT) and inorganic tin. In 7 days, approximately 80 % of TBT degradation was achieved, generating close to 20 % of DBT as degradation product. The degradation rate constant (k) was 0.022 [day(-1)] and TBT half-life (t1/2) in culture was 4.3 days. Debutylation is stated a probable mechanism of TBT degradation.
Assuntos
Bactérias/metabolismo , Clima Desértico , Compostos Orgânicos de Estanho/análise , Estanho/análise , Compostos de Trialquitina/análise , Alcaligenes/metabolismo , Biodegradação Ambiental , Burkholderia cepacia/metabolismo , Chile , Farmacorresistência Bacteriana , Sedimentos Geológicos/química , Meia-Vida , Moraxella/metabolismo , Pseudomonas/metabolismo , Rios , Solo , Microbiologia do Solo , Poluentes do Solo/análise , Fatores de Tempo , Poluentes da Água/análise , Yersinia/metabolismoRESUMO
Sugar esters are considered as surfactants due to its amphiphilic balance that can lower the surface tension in oil/water mixtures. Enzymatic syntheses of these compounds are interesting both from economic and environmental considerations. A study was carried out to evaluate the effect of four solvents, temperature, substrate molar ratio, biocatalyst source, and immobilization methodology on the yield and specific productivity of lactulose palmitate monoester synthesis. Lipases from Pseudomonas stutzeri (PsL) and Alcaligenes sp. (AsL), immobilized in porous silica functionalized with octyl groups (adsorption immobilization, OS) and with glyoxyl-octyl groups (both adsorption and covalent immobilization, OGS), were used. The highest lactulose palmitate yields were obtained at 47 °C in acetone, for all biocatalysts, while the best lactulose:palmitic acid molar ratio differed according to the immobilization methodology, being 1:1 for AsL-OGS biocatalyst (20.7 ± 3%) and 1:3 for the others (30-50%).
Assuntos
Proteínas de Bactérias/química , Lactulose/química , Lipase/química , Palmitatos/química , Alcaligenes/enzimologia , Biocatálise , Estabilidade Enzimática , Enzimas Imobilizadas/química , Pseudomonas/enzimologiaRESUMO
Lipase-catalyzed synthesis of sugar esters, as lactulose palmitate, requires harsh conditions, making it necessary to immobilize the enzyme. Therefore, a study was conducted to evaluate the effect of different chemical surfaces of hierarchical meso-macroporous silica in the immobilization of two lipases from Pseudomonas stutzeri (PsL) and Alcaligenes sp. (AsL), which exhibit esterase activity. Porosity and chemical surface of silica supports, before and after functionalization and after immobilization, were characterized by gas adsorption and Fourier transform infrared (FTIR) spectroscopy. PsL and AsL were immobilized in octyl (OS), glyoxyl (GS), and octyl-glyoxyl silica (OGS). Hydrolytic activity, thermal and solvent stability, and sugar ester synthesis were evaluated with those catalysts. The best support in terms of expressed activity was OS in the case of PsL (100 IU g(-1)), while OS and OGS were the best for AsL with quite similar expressed activities (60 and 58 IU g(-1), respectively). At 60 °C in aqueous media the more stable biocatalysts were GS-PsL and OGS-AsL (half-lives of 566 and 248 h, respectively), showing the advantage of a heterofunctional support in the latter case. Lactulose palmitate synthesis was carried out in acetone medium (with 4% of equilibrium moisture) at 40 °C obtaining palmitic acid conversions higher than 20% for all biocatalysts, being the highest of those obtained with OGS-AsL and OS-PsL. Therefore, screening of different chemical surfaces on porous silica used as supports for lipase immobilization allowed obtaining active and stable biocatalyst to be employed in the novel synthesis of lactulose palmitate.
Assuntos
Enzimas Imobilizadas/química , Lactulose/análogos & derivados , Lipase/metabolismo , Palmitatos/metabolismo , Dióxido de Silício/metabolismo , Alcaligenes/enzimologia , Biocatálise , Enzimas Imobilizadas/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Lactulose/biossíntese , Lactulose/química , Lipase/química , Palmitatos/química , Tamanho da Partícula , Porosidade , Pseudomonas stutzeri/enzimologia , Dióxido de Silício/química , Propriedades de SuperfícieRESUMO
Mounier-Kuhn syndrome is a rare entity characterized by abnormal dilatation of the trachea and main bronchi (tracheobronchomegaly). Alcaligenes xylosoxidans is a non fermenting gram-negative pathogen common in extra-and intra-hospital environment, which may be related to immunosuppression states. We describe the case of a 75 years old male, ex-smoker with moderate functional obstruction, chronic respiratory failure and chronic colonization by Pseudomonas aeuriginosa. He had an infectious exacerbation of his disease, reason that previously required several hospital admissions. The patient was treated with antibiotics and his evolution was favourable with negativization in cultures of the pathogen. This is the first description of the isolation of Alcaligenes xylosoxidans as a cause of respiratory infection in a patient with Mounier-Kuhn syndrome.
Assuntos
Idoso , Humanos , Masculino , Alcaligenes/isolamento & purificação , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções Respiratórias/microbiologia , Traqueobroncomegalia/complicações , Infecções por Bactérias Gram-Negativas/complicações , Infecções Respiratórias/complicaçõesRESUMO
Mounier-Kuhn syndrome is a rare entity characterized by abnormal dilatation of the trachea and main bronchi (tracheobronchomegaly). Alcaligenes xylosoxidans is a non fermenting gram-negative pathogen common in extra-and intra-hospital environment, which may be related to immunosuppression states. We describe the case of a 75 years old male, ex-smoker with moderate functional obstruction, chronic respiratory failure and chronic colonization by Pseudomonas aeuriginosa. He had an infectious exacerbation of his disease, reason that previously required several hospital admissions. The patient was treated with antibiotics and his evolution was favourable with negativization in cultures of the pathogen. This is the first description of the isolation of Alcaligenes xylosoxidans as a cause of respiratory infection in a patient with Mounier-Kuhn syndrome.