RESUMEN
Considering that bacterial biosurfactants (BSFs) are released as secondary metabolites involved in biotic relations within mixed bacterial assemblages, the hypothesis that the co-cultivation of BSF producing bacteria with biofilm-forming strains would enhance BSF synthesis was tested. Environmental BSF producing strains of Bacillus licheniformis and Pseudomonas sp. were cultivated with reference biofilm-forming strains (Pseudomonas aeruginosa and Listeria innocua). BSF production and quorum-quenching effects were tested in solid media. Tensioactive and anionic BSFs were also quantified in cell-free extracts (CFEs). BSF production increased in co-cultures with inducer strains although this was not demonstrated by all screening methods. Increased concentrations of anionic BSF were detected in CFEs of co-cultures in which Pseudomonas aeruginosa was included as inducer, which is in accordance with the observation of larger halos in cetyl trimethylammonium bromide-methylene blue agar. The results demonstrate that co-cultivation positively affects the efficiency of BSF production and that higher production yields may be attained by selecting convenient inducer partners in designed consortia. SIGNIFICANCE AND IMPACT OF THE STUDY: The high production cost of biosurfactants (BSFs) still represents a major limitation to the industrial use of these otherwise advantageous alternatives to chemical surfactants. This work demonstrates that the co-cultivation of consortia of biosurfactant-producer and biofilm-forming bacteria enhances BSF production and may contribute to the cost-effectiveness of biosurfactant-based products.
Asunto(s)
Bacillus licheniformis/metabolismo , Biopelículas/crecimiento & desarrollo , Listeria/metabolismo , Pseudomonas aeruginosa/metabolismo , Tensoactivos/metabolismo , Agar/metabolismo , Técnicas de Cocultivo , Percepción de QuorumRESUMEN
Near infrared (NIR) spectroscopy was used to determine the content of Klason lignin, acid-soluble lignin, total lignin, extractives, ash, acid-insoluble residue, glucose, xylose, rhamnose, galactose, arabinose, mannose and total sugars in coconut residues. The samples were analyzed at several processing stages: wet unground (WU), dried unground (DU) and dried and sieved (DS). Partial least squares models were built, and the models for the analytes exhibited R(2)>0.80, with the exceptions of rhamnose, arabinose, galactose, mannose and ash from all fractions, and the lignin content from the WU fraction, which were predicted poorly (R(2)<0.70). There were some significant differences between the models for the main lignocellulosic components at the various stages of biomass. These results proved that NIR spectroscopy is useful for analysis at biorefineries, and it can be used as a faster and more economical alternative to the standard methods.
Asunto(s)
Cocos/química , Análisis de los Alimentos/métodos , Lignina/análisis , Extractos Vegetales/análisis , Espectroscopía Infrarroja Corta/métodos , Análisis MultivarianteRESUMEN
In newborn infant, cerebral infarction is often difficult to distinguish from cerebral hemorrhage, both pathologies being moreover frequently associated. We report a left anterior stroke in a fullterm newborn who had seizures on the third day of life. Ultrasound scanning showed a hyperechogenic zone in the territory of the left anterior cerebral artery. Pulsed and color Doppler imaging showed a decreased blood flow velocity in comparison to the opposite side, thus enabling the diagnosis.
Asunto(s)
Isquemia Encefálica/diagnóstico por imagen , Infarto Cerebral/diagnóstico por imagen , Ecoencefalografía , Ultrasonografía Doppler en Color , Ultrasonografía Doppler de Pulso , Velocidad del Flujo Sanguíneo , Arterias Cerebrales/diagnóstico por imagen , Hemorragia Cerebral/diagnóstico , Circulación Cerebrovascular , Diagnóstico Diferencial , Humanos , Recién Nacido , Masculino , Convulsiones/diagnósticoRESUMEN
'SequenceSpace' analysis is a novel approach which has been used to identify unique amino acids within a sub-family of phospholipases A2 (PLA2) in which the highly conserved active site residue Asp49 is substituted by Lys (Lys49-PLA2s). Although Lys49-PLA2s do not bind the catalytic co-factor Ca2+ and possess extremely low catalytic activity, they demonstrate a Ca2+-independent membrane damaging activity through a poorly understood mechanism, which does not involve lipid hydrolysis. Additionally, Lys49-PLA2s possess combined myotoxic, oedema forming and cardiotoxic pharmacological activities, however the structural basis of these varied functions is largely unknown. Using the 'SequenceSpace' analysis we have identified nine residues highly unique to the Lys49-PLA2 sub-family, which are grouped in three amino acid clusters in the active site, hydrophobic substrate binding channel and homodimer interface regions. These three highly specific residue clusters may have relevance for the Ca2+-independent membrane damaging activity. Of a further 15 less stringently conserved residues, nine are located in two additional clusters which are well isolated from the active site region. The less strictly conserved clusters have been used in predictive sequence searches to correlate amino acid patterns in other venom PLA2s with their pharmacological activities, and motifs for presynaptic and combined toxicities are proposed.
Asunto(s)
Lisina/química , Músculos/patología , Fosfolipasas A/química , Secuencia de Aminoácidos , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Modelos Moleculares , Datos de Secuencia Molecular , Músculos/efectos de los fármacos , Fosfolipasas A/toxicidad , Fosfolipasas A2 , Homología de Secuencia de Aminoácido , Venenos de Serpiente/enzimologíaRESUMEN
In 5 patients with portal hypertension caused by schistosomiasis, the sinusoidal pressure (wedged hepatic pressure) varied from 20.7 to 35.4 mm Hg. While the catheter was in an occluded position within the hepatic vein and the patients were undergoing splenectomy, the main trunk of the hepatic artery was clamped. The sinusoidal pressures then fell to levels that varied from 3.7 to 7.4 mm Hg but returned to previous levels when the clamping was released. Wedged hepatic venous pressure levels, which were significantly greater than portal venous pressure values, decreased minimally after splenectomy. Portal venous pressure levels, however, fell to 63% of presplenectomy levels. In a control case with an enlarged spleen (cavernous hemangioma, but with a normal liver, the wedged hepatic pressure was 7.4 mm Hg and showed no alteration after clamping of hepatic artery. These data point out the importance of hepatic artery hypertrophy, that has already been demonstrated in other studies, in causing elevation of the wedged hepatic pressure in advanced hepatic schistosomiasis.