RESUMO
A biofilm developed from low quality green coffee beans was tested for its capacity to degrade the polynuclear aromatic hydrocarbon (PAH), phenanthrene (Phe), in seawater. Microorganisms were immobilized on two types of Luffa cylindrica (with three and four placental cavities), and the effects of moisture content (20, 30 and 40% of water holding capacity) and particle size (<0.42 mm, 0.42-0.86 mm and 0.86-2.0 mm) of green coffee beans on microbial activity were considered. Biofilm growth determined by respirometry showed a highest microbial activity at a moisture content of 40% and particle size of 0.42-0.86 mm. The loofah fiber with three placental cavities showed the highest adherence of microorganisms. The kinetics of microbial growth in both seawater and distilled water and the scanning electron microscopies indicated that the microorganisms associated with green coffee beans are halotolerant. In fact, I-GCB-SW-G biofilm degraded 67.56% of Phe (50 mg L-1) in seawater, at a significantly higher rate than in distilled water (I-GCB-DW-W).
Assuntos
Biofilmes/crescimento & desenvolvimento , Café/química , Luffa/química , Fenantrenos/análise , Água do Mar/química , Poluentes Químicos da Água/análise , Biodegradação Ambiental , Resíduos Industriais/análise , Consórcios Microbianos , Salinidade , Propriedades de SuperfícieRESUMO
An economic, simple, quantitative, and non-chromatographic method for the determination of alcohols using microdiffusion principle has been adapted and validated for acetone-butanol-ethanol (ABE) fermentation samples. This method, based on alcohols oxidation using potassium dichromate in acid medium, and detection by spectrophotometry, was evaluated varying, both, temperature (35°C, 45°C, and 55°C) and reaction time (0 to 125min). With a sample analysis time of 90min at 45°C, a limit of detection (LOD), and a limit of quantification (LOQ) of 0.10, and 0.40g/L, respectively. The proposed method has been successfully applied to determine butanol and ethanol concentrations in ABE fermentation samples with the advantage that multiple samples can be analyzed simultaneously. The measurements obtained with the proposed method were in good agreement with those obtained with the Gas Chromatography Method (GCM). This proposed method is useful for routine analysis of alcohols and screening samples in laboratories and industries.
Assuntos
Butanóis/análise , Clostridium acetobutylicum/metabolismo , Etanol/análise , Espectrofotometria/métodos , Biocombustíveis/análise , Cromatografia Gasosa/métodos , Difusão , Fermentação , Limite de Detecção , Espectrofotometria/instrumentaçãoRESUMO
The effect of recalcitrant hydrocarbons on the fatty acid profile from leaf, basal corm, and roots of Cyperus laxus plants cultivated in greenhouse phytoremediation systems of soils from aged oil spill-impacted sites containing from 16 to 340 g/Kg total hydrocarbons (THC) was assessed to investigate if this is a C18:3 species and if the hydrocarbon removal during the phytoremediation process has a relationship with the fatty acid profile of this plant. The fatty acid profile was specific to each vegetative organ and was strongly affected by the hydrocarbons level in the impacted sites. Leaf extracts of plants from uncontaminated soil produced palmitic acid (C16), octadecanoic acid (C18:0), unsaturated oleic acids (C18:1-C18:3), and unsaturated eichosanoic (C20:2-C20:3) acids with a noticeable absence of the unsaturated hexadecatrienoic acid (C16:3); this finding demonstrates, for the first time, that C. laxus is a C18:3 plant. In plants from the phytoremediation systems, the total fatty acid contents in the leaf and the corm were negatively affected by the hydrocarbons presence; however, the effect was positive in root. Interestingly, under contaminated conditions, unusual fatty acids such as odd numbered carbons (C15, C17, C21, and C23) and uncommon unsaturated chains (C20:3n6 and C20:4) were produced together with a remarkable quantity of C22:2 and C24:0 chains in the corm and the leaf. These results demonstrate that weathered hydrocarbons may drastically affect the lipidic composition of C. laxus at the fatty acid level, suggesting that this species adjusts the cover lipid composition in its vegetative organs, mainly in roots, in response to the weathered hydrocarbon presence and uptake during the phytoremediation process.
Assuntos
Cyperus/metabolismo , Ácidos Graxos/metabolismo , Poluição por Petróleo , Folhas de Planta/metabolismo , Solo/química , Biodegradação AmbientalRESUMO
Discharge of dye-containing wastewater by the textile industry can adversely affect aquatic ecosystems and human health. Bioremoval is an alternative to industrial processes for detoxifying water contaminated with dyes. In this work, active and inactive biomass of the microalga Chlorella vulgaris was assayed for the ability to remove Congo Red (CR) dye from aqueous solutions. Through biosorption and biodegradation processes, Chlorella vulgaris was able to remove 83 and 58 % of dye at concentrations of 5 and 25 mg L(-1), respectively. The maximum adsorption capacity at equilibrium was 200 mg g(-1). The Langmuir model best described the experimental equilibrium data. The acute toxicity test (48 h) with two species of cladocerans indicated that the toxicity of the dye in the effluent was significantly decreased compared to the initial concentrations in the influent. Daphnia magna was the species less sensitive to dye (EC50 = 17.0 mg L(-1)), followed by Ceriodaphnia dubia (EC50 = 3.32 mg L(-1)). These results show that Chlorella vulgaris significantly reduced the dye concentration and toxicity. Therefore, this method may be a viable option for the treatment of this type of effluent.
Assuntos
Chlorella vulgaris/metabolismo , Corantes/metabolismo , Vermelho Congo/metabolismo , Poluentes Químicos da Água/metabolismo , Adsorção , Animais , Compostos Azo/metabolismo , Compostos Azo/toxicidade , Biodegradação Ambiental , Cladocera/efeitos dos fármacos , Corantes/toxicidade , Vermelho Congo/toxicidade , Daphnia/efeitos dos fármacos , Concentração Inibidora 50 , Indústria Têxtil , Testes de Toxicidade Aguda , Águas Residuárias/química , Poluentes Químicos da Água/toxicidade , Purificação da ÁguaRESUMO
The Cfl xyn11A gene, encoding the endo-1,4-beta-xylanase Cfl Xyn11A from Cellulomonas flavigena, was isolated from a genomic DNA library. The open reading frame of the Cfl xyn11A gene was 999 base pairs long and encoded a polypeptide (Cfl Xyn11A) of 332 amino acids with a calculated molecular mass of 35,110Da. The Cfl xyn11A gene was expressed in Escherichia coli and the recombinant enzyme, with an estimated molecular weight of 31kDa was purified and xylanase activity was measured. Cfl Xyn11A showed optimal activity at pH 6.5 and 55 degrees C. The enzyme demonstrated moderate thermal stability as Cfl Xyn11A maintained 50% of its activity when incubated at 55 degrees C for 1h or at 45 degrees C for 6h. This is the first report describing the cloning, expression and functional characterization of an endo-1,4-beta-xylanase-encoding gene from C. flavigena. Cfl Xyn11A may be suitable for industrial applications in the food and feed industries, or in the pre-treatment of lignocellulosic biomass required to improve the yields of fermentable sugars for bioethanol production.
Assuntos
Cellulomonas/genética , Cellulomonas/metabolismo , Endo-1,4-beta-Xilanases/química , Biomassa , Clonagem Molecular , DNA/metabolismo , Regulação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica , Biblioteca Gênica , Genoma Bacteriano , Concentração de Íons de Hidrogênio , Microbiologia Industrial/métodos , Lignina/química , Plasmídeos/metabolismo , Temperatura , Fatores de TempoRESUMO
Synthesis of extracellular xylanase in Cellulomonas flavigena is induced in the presence of xylan and sugarcane bagasse as substrates. The essential factors for efficient production of xylanase are the appropriate medium composition and an inducing substrate. The increase in xylanase production levels in C. flavigena were tested with a number of carbon sources and different culture conditions. Xylose, arabinose, glycerol and glucose did not induce xylanase production in this microorganism. beta-Methyl-xyloside (beta-mx), a structural analog of xylobiose, also did not induce xylanase when used as the sole carbon source, but when xylan or sugar cane bagasse was supplemented with beta-mx, extracellular xylanase production increased by 25 or 46%, respectively. The response of C. flavigena to xylan plus beta-mx was accompanied by a significant accumulation of reducing sugar, an effect not observed with the combination sugarcane bagasse plus beta-mx as substrate. To our knowledge, this is the first report on the effect of beta-mx on the induction of xylanase in C. flavigena.