RESUMO
Biodesulfurization (BDS) in a bioreactor packed with a catalytic bed of silica containing immobilized Rhodococcus rhodochrous was studied. Various bed lengths and support particle sizes were evaluated for BDS of dibenzothiophene (DBT) and gas oil. The sulfur-containing substrates were introduced separately into the bioreactor at different feed flows. Higher removal of sulfur from DBT and gas oil was achieved with a long bed, lower substrate flow, and larger sizes of immobilization particles. The packed bed bioreactor containing metabolic active cells was recycled and maintained BDS activity.
Assuntos
Biocatálise , Reatores Biológicos/microbiologia , Gases/isolamento & purificação , Óleos/isolamento & purificação , Rhodococcus/metabolismo , Dióxido de Silício/farmacologia , Enxofre/isolamento & purificação , Tiofenos/isolamento & purificação , Biocatálise/efeitos dos fármacos , Biodegradação Ambiental/efeitos dos fármacos , Células Imobilizadas/citologia , Células Imobilizadas/efeitos dos fármacos , Tamanho da Partícula , Reciclagem , Rhodococcus/citologia , Rhodococcus/efeitos dos fármacos , Fatores de TempoRESUMO
Two immobilized preparations from Thermomyces lanuginosus lipase (TLL) were compared in the synthesis of butyl butyrate. The commercial Lipozyme TL-IM, and TLL immobilized on styrene-divinylbenzene beads (MCI-TLL) were tested in the esterification reaction using n-hexane as solvent. The variables temperature (30-60°C), substrate molar ratio (1:1 to 5:1), added water (0-1%), and biocatalyst content (3-40%) were evaluated in terms of initial reaction rate for each biocatalyst. SDS-PAGE analysis revealed that MCI-TLL had an immobilized enzymatic load twice as high as Lipozyme TL-IM, but with an activity 3-fold higher. MCI-TLL presented high initial reaction rates up to 1.0 M butyric acid, while Lipozyme TL-IM showed a decrease in its activity above 0.5 M. Moreover, MCI-TLL allowed a productivity of 14.5 mmol g(-1) h(-1), while Lipozyme TL-IM 3.2 mmol g(-1) h(-1), both by mass of biocatalyst.
Assuntos
Ascomicetos/enzimologia , Biotecnologia/métodos , Butiratos/metabolismo , Lipase/metabolismo , Microesferas , Estireno/farmacologia , Compostos de Vinila/farmacologia , Ascomicetos/citologia , Ascomicetos/efeitos dos fármacos , Biocatálise/efeitos dos fármacos , Butiratos/farmacologia , Células Imobilizadas/citologia , Células Imobilizadas/efeitos dos fármacos , Células Imobilizadas/enzimologia , Eletroforese em Gel de Poliacrilamida , Esterificação/efeitos dos fármacos , Cinética , Especificidade por Substrato/efeitos dos fármacos , Temperatura , Água/farmacologiaRESUMO
This research aimed at investigating the cryoprotectant action of glucose and lactose on strains of Malassezia spp. and zygomycetes immobilised in sodium alginate. Twelve strains of Malassezia spp. (nine M. furfur, two M. globosa and one M. sympodialis) and 12 zygomycetes (five Rhizopus oryzae and seven Mucor hiemales) were immobilised in sodium alginate, within plastic beads, maintained in appropriate media containing glucose and lactose at concentrations of 9% and 23% and preserved at temperatures of -20 and -80 °C. Strain viability was evaluated from 15 to 270 days of storage, through the observation of macro-micromorphologic characteristics. The Malassezia spp. strains were only viable until 90 days of storage, whereas for zygomycetes, viable strains were observed until after 270 days of storage at -80 °C, in the media containing 23% glucose or lactose. The use of 23% glucose or lactose at -80 °C in a sodium alginate cell immobilisation system is efficient for cryopreserving zygomycetes. This research creates perspectives for the use of glucose and lactose in sodium alginate cell immobilisation systems for the preservation of fungi with low viability.
Assuntos
Alginatos/metabolismo , Crioprotetores/farmacologia , Glucose/farmacologia , Lactose/farmacologia , Rhizopus/efeitos dos fármacos , Adesão Celular/efeitos dos fármacos , Células Imobilizadas/efeitos dos fármacos , Criopreservação/métodos , Meios de Cultura/metabolismo , Ácido Glucurônico/metabolismo , Ácidos Hexurônicos/metabolismo , Viabilidade Microbiana , Mucor/efeitos dos fármacos , Mucor/metabolismo , Rhizopus/metabolismo , TemperaturaRESUMO
The herbicide propanil has long been used in rice production in southern Brazil. Bacteria isolated from contaminated soils in Massaranduba, Santa Catarina, Brazil, were found to be able to grow in the presence of propanil, using this compound as a carbon source. Thirty strains were identified as Pseudomonas (86.7%), Serratia (10.0%), and Acinetobacter (3.3%), based on phylogenetic analysis of 16S rDNA. Little genetic diversity was found within species, more than 95% homology, suggesting that there is selective pressure to metabolize propanil in the microbial community. Two strains of Pseudomonas (AF7 and AF1) were selected in bioreactor containing chemotactic growth medium, with the highest degradation activity of propanil exhibited by strain AF7, followed by AF1 (60 and 40%, respectively). These strains when encapsulated in alginate exhibited a high survival rate and were able to colonize the rice root surfaces. Inoculation with Pseudomonas strains AF7 and AF1 significantly improved the plant height of rice. Most of the Pseudomonas strains produced indoleacetic acid, soluble mineral phosphate, and fixed nitrogen. These bacterial strains could potentially be used for the bioremediation of propanil-contaminated soils and the promotion of plant growth.
Assuntos
Bactérias/genética , Bactérias/isolamento & purificação , Variação Genética , Oryza/crescimento & desenvolvimento , Oryza/microbiologia , Propanil/metabolismo , Rizosfera , Alginatos , Bactérias/metabolismo , Bactérias/ultraestrutura , Sequência de Bases , Biodegradação Ambiental/efeitos dos fármacos , Células Imobilizadas/citologia , Células Imobilizadas/efeitos dos fármacos , Células Imobilizadas/ultraestrutura , DNA Ribossômico/genética , Ácido Glucurônico , Ácidos Hexurônicos , Microesferas , Oryza/efeitos dos fármacos , Filogenia , Propanil/farmacologia , Pseudomonas/efeitos dos fármacos , Pseudomonas/genética , Pseudomonas/crescimento & desenvolvimento , Pseudomonas/ultraestrutura , Transformação Genética/efeitos dos fármacosRESUMO
Diplogelasinospora grovesii has been reported as a very active biocatalyst in the reduction of ketones. Along the text, the properties of this filamentous fungus as an immobilized catalyst are described. For this purpose, several immobilization supports as agar and polyurethane foam were tested. Experimental assays were also performed to test different co-substrates for the regeneration of the required enzyme cofactor. The fungus immobilized in polyurethane foam lead to the most stable and active catalyst. This derivative, using i-PrOH as co-substrate, could be reused at least 18 times without appreciable activity loss (>90% activity remains). Kinetic runs experiments shown that the reduction of cyclohexanone, selected as model substrate, followed a pseudo-first kinetic order and that the rate controlling step was the mass transfer through the cell wall. The deactivation kinetic constants were also determined. The reduction of different chiral ketones showed that the ketone reductase activity followed the Prelog's rule.
Assuntos
Biocatálise/efeitos dos fármacos , Cetonas/metabolismo , Poliuretanos/farmacologia , Sordariales/citologia , Sordariales/metabolismo , Células Imobilizadas/citologia , Células Imobilizadas/efeitos dos fármacos , Células Imobilizadas/metabolismo , Cicloexanóis/metabolismo , Cicloexanonas/metabolismo , Difusão/efeitos dos fármacos , Cetonas/química , Cinética , Oxirredução/efeitos dos fármacos , Reciclagem , Sordariales/efeitos dos fármacos , Estereoisomerismo , Especificidade por Substrato/efeitos dos fármacosRESUMO
Adhesion of Pseudomonas putida F1 onto agave-fiber/recycled-polyethylene foamed composites was studied under different controlled conditions. The adhesion process was analyzed in batch experiments controlling factors such as pH, contact time, temperature, initial biomass concentration and ionic strength; and was verified by scanning electron microscopy (SEM). The number of adhered bacteria after the experimental time was determined by difference between concentration of suspended cells in NaCl solution contained in two different Erlenmeyer flasks, one of the flasks with composite pellets and the other one without them. The concentration of cells in each flask was obtained using the serial dilution technique. Experimental data analysis showed that adsorption follows first-order kinetics. And it was further corroborated to be an irreversible process. For the first time, an equation is proposed here to predict the correlation between adhered bacteria and aqueous pH. In addition to the obvious reuse of waste material, these results suggested that agave-fiber/polymer foamed composites could be used as support for bacterial immobilization to be applied, among others in environmental processes such as bioremediation and biofiltration of gases with almost limitless possibilities.
Assuntos
Agave/microbiologia , Aderência Bacteriana/efeitos dos fármacos , Polietileno/farmacologia , Pseudomonas putida/citologia , Pseudomonas putida/efeitos dos fármacos , Biomassa , Células Imobilizadas/citologia , Células Imobilizadas/efeitos dos fármacos , Concentração de Íons de Hidrogênio/efeitos dos fármacos , Cinética , Concentração Osmolar , Pseudomonas putida/ultraestrutura , Cloreto de Sódio/farmacologia , Temperatura , Fatores de TempoRESUMO
The photodynamic action of 5-(4-trifluorophenyl)-10,15,20-tris(4-trimethylammoniumphenyl)porphyrin iodide (TFAP(3+)) and 5,10,15,20-tetra(4-N,N,N-trimethylammonium phenyl)porphyrin p-tosylate (TMAP(4+)) has been studied in vitro on Candida albicans. The results of these cationic porphyrins were compared with those of 5,10,15,20-tetra(4-sulphonatophenyl)porphyrin (TPPS(4-)), which characterizes an anionic sensitizer. In vitro investigations show that these cationic porphyrins are rapidly bound to C. albicans cells, reaching a value of approximately 1.4 nmol/10(6) cells, when the cellular suspensions were incubated with 5 microM sensitizer for 30 min. In contrast, TPPS(4-) is poorly uptaken by yeast cells. The fluorescence spectra of these sensitizers into the cells confirm this behaviour. The amount of porphyrin binds to cells is dependent on both sensitizer concentrations (1-5 microM) and cells densities (10(6)-10(8) cells/mL). Photosensitized inactivation of C. albicans cellular suspensions increases with sensitizer concentration, causing a approximately 5 log decrease of cell survival, when the cultures are treated with 5 microM of cationic porphyrin and irradiated for 30 min. However, the photocytotoxicity decreases with an increase in the cell density, according to its low binding to cells. Under these conditions, the photodynamic activity of TFAP(3+) is quite similar to that produced by TMAP(4+), whereas no important inactivation effect was found for TPPS(4)(-). The high photodynamic activity of cationic porphyrins was confirmed by growth delay experiments. Thus, C. albicans cell growth was not detected in the presence of 5 microM TFAP(3+). Photodynamic inactivation capacities of these sensitizers were also evaluated on C. albicans cells growing in colonies on agar surfaces. Cationic porphyrins produce a growth delay of C. albicans colonies and viability of cells was not observed after 3 h irradiation, indicating a complete inactivation of yeast cells. Therefore, these results indicate that these cationic porphyrins are interesting sensitizers for photodynamic inactivation of yeasts in liquid suspensions or in localized foci of infection.
Assuntos
Candida albicans/efeitos dos fármacos , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Porfirinas/química , Porfirinas/farmacologia , Absorção , Soluções Tampão , Candida albicans/citologia , Candida albicans/metabolismo , Candida albicans/efeitos da radiação , Candidíase/tratamento farmacológico , Proliferação de Células/efeitos dos fármacos , Células Imobilizadas/citologia , Células Imobilizadas/efeitos dos fármacos , Meios de Cultura , Luz , Processos Fotoquímicos , Fármacos Fotossensibilizantes/metabolismo , Fármacos Fotossensibilizantes/uso terapêutico , Porfirinas/metabolismo , Porfirinas/uso terapêutico , Espectrometria de FluorescênciaRESUMO
The photodynamic activity of 5,10,15-tris[4-(3-N,N,N-trimethylammoniumpropoxy)phenyl]-20-(4-trifluoromethylphenyl)porphyrin iodide (A3B3+) has been studied in vitro on a typical Gram-negative bacterium Escherichia coli immobilized on agar surfaces. The results obtained for the tricationic A3B3+ porphyrin were compared with those of 5,10,15,20-tetra(4-N,N,N-trimethylammoniumphenyl)porphyrin p-tosylate (TTAP4+), which is a standard active sensitizer established to eradicate E. coli in cellular suspension. The photobleaching of these porphyrins in solution was evaluated by decay in absorbance and in fluorescence. In both cases, a higher photostability was found for A3B3+ than for TTAP4+. Photodynamic inactivation capacities of these sensitizers were analyzed in E. coli cells immobilized on agar surfaces. Small colonies were treated with different amount of sensitizer (0-14 nmol) and irradiated with visible light for 3h. The light source used was either a projector or midday sun. The A3B3+ porphyrin produced a growth delay of E. coli colonies on agar surfaces. Similar result was obtained irradiating only one isolated colony through an optical fiber. Under these conditions, A3B3+ porphyrin shows a high activity to inactivate localized bacterial cells. The higher photodynamic activity of A3B3+ was confirmed by mechanical spreading of the colonies before treatment. This procedure produces complete inactivation of E. coli cells on the agar surface. Therefore, tricationic A3B3+ porphyrin is an interesting sensitizer with potential applications in photodynamic inactivation of bacteria growing as localized foci of infection.
Assuntos
Ágar/química , Escherichia coli/efeitos dos fármacos , Fármacos Fotossensibilizantes/farmacologia , Porfirinas/farmacologia , Cátions/química , Cátions/farmacologia , Células Imobilizadas/efeitos dos fármacos , Células Imobilizadas/efeitos da radiação , Escherichia coli/citologia , Escherichia coli/efeitos da radiação , Técnicas In Vitro , Luz , Testes de Sensibilidade Microbiana , Estrutura Molecular , Fármacos Fotossensibilizantes/química , Porfirinas/química , Relação Estrutura-Atividade , Propriedades de SuperfícieRESUMO
The polyhydroxylated silane network of a sol-gel protected immobilised Saccharomyces cerevisiae against the effects of five organic solvents. The viability of immobilised yeast directly correlated with the logarithm of the partition coefficient of the solvent in an octanol/water two phase system increasing the decimal reduction time (D) and reaching the maximum with octanol, the most hydrophobic solvent assayed. The D value increased from 0.16 min for free yeast to 1.9 and to 22 min for immobilised yeast exposed to ethanol and 1-octanol respectively.