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ABSTRACT This study aimed to investigate the impact of nonionic surfactants on the efficacy of fluorine degradation by Polyporus sp. S133 in a liquid culture. Fluorene was observed to be degraded in its entirety by Polyporus sp. S133 subsequent to a 23-day incubation period. The fastest cell growth rate was observed in the initial 7 days in the culture that was supplemented with Tween 80. The degradation process was primarily modulated by the activity of two ligninolytic enzymes, laccase and MnP. The highest laccase activity was stimulated by the addition of Tween 80 (2443 U/L) followed by mixed surfactant (1766 U/L) and Brij 35 (1655 U/L). UV-vis spectroscopy, TLC analysis and mass spectrum analysis of samples subsequent to the degradation process in the culture medium confirmed the biotransformation of fluorene. Two metabolites, 9-fluorenol (λmax 270, tR 8.0 min and m/z 254) and protocatechuic acid (λmax 260, tR 11.3 min and m/z 370), were identified in the treated medium.

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RESUMEN

This study aimed to investigate the impact of nonionic surfactants on the efficacy of fluorine degradation by Polyporus sp. S133 in a liquid culture. Fluorene was observed to be degraded in its entirety by Polyporus sp. S133 subsequent to a 23-day incubation period. The fastest cell growth rate was observed in the initial 7 days in the culture that was supplemented with Tween 80. The degradation process was primarily modulated by the activity of two ligninolytic enzymes, laccase and MnP. The highest laccase activity was stimulated by the addition of Tween 80 (2443 U/L) followed by mixed surfactant (1766 U/L) and Brij 35 (1655 U/L). UV-vis spectroscopy, TLC analysis and mass spectrum analysis of samples subsequent to the degradation process in the culture medium confirmed the biotransformation of fluorene. Two metabolites, 9-fluorenol (max 270, tR 8.0 min and m/z 254) and protocatechuic acid (max 260, tR 11.3 min and m/z 370), were identified in the treated medium.(AU)

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RESUMEN

This study aimed to investigate the impact of nonionic surfactants on the efficacy of fluorine degradation by Polyporus sp. S133 in a liquid culture. Fluorene was observed to be degraded in its entirety by Polyporus sp. S133 subsequent to a 23-day incubation period. The fastest cell growth rate was observed in the initial 7 days in the culture that was supplemented with Tween 80. The degradation process was primarily modulated by the activity of two ligninolytic enzymes, laccase and MnP. The highest laccase activity was stimulated by the addition of Tween 80 (2443U/L) followed by mixed surfactant (1766U/L) and Brij 35 (1655U/L). UV-vis spectroscopy, TLC analysis and mass spectrum analysis of samples subsequent to the degradation process in the culture medium confirmed the biotransformation of fluorene. Two metabolites, 9-fluorenol (λmax 270, tR 8.0min and m/z 254) and protocatechuic acid (λmax 260, tR 11.3min and m/z 370), were identified in the treated medium.

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To gain a better understanding of the interactions governing the binding mechanism of proteins with non-ionic surfactants, the association processes of Tween 20 and Tween 80 with the bovine serum albumin (BSA) protein were investigated using molecular dynamics (MD) simulations. Protein:surfactant molar ratios were chosen according to the critical micelle concentration (CMC) of each surfactant in the presence of BSA. It was found that both the hydrophilic and the hydrophobic groups of the BSA equally contribute to the surface area of interaction with the non-ionic surfactants. A novel theoretical model for the interactions between BSA and these surfactants at the atomic level is proposed, where both surfactants bind to non-specific domains of the BSA three-dimensional structure mainly through their polyoxyethylene groups, by hydrogen bonds and van der Waals interactions. This is well supported by the strong electrostatic and van der Waals interaction energies obtained in the calculations involving surfactant polyoxyethylene groups and different protein regions. The results obtained from the MD simulations suggest that the formation of surfactant clusters over the BSA structure, due to further cooperative self-assembly of Tween molecules, could increase the protein conformational stability. These results extend the current knowledge on molecular interactions between globular proteins and non-ionic surfactants, and contribute to the fine-tuning design of protein formulations using polysorbates as excipients for minimizing the undesirable effects of protein adsorption and aggregation.

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En Colombia, el surfactante Cosmoflux® 411F es usado en fumigaciones de cultivos ilícitos para mejorar la efectividad del glifosato. El uso del Cosmoflux® 411F no está soportado por estudios toxicológicos. Los objetivos del presente trabajo fueron determinar las lesiones anatomopatológicas derivadas de la exposición al Cosmoflux® 411F y establecer la concentración letal 50 (CL50) a 96 horas en cachama blanca (Piaractus brachypomus). Se utilizaron juveniles de cachama blanca (40 g) en dos experimentos: 1) toxicidad subletal (n =126) y, 2) determinación de la CL50 (n =84). Las concentraciones del ensayo de toxicidad subletal fueron: 0 mg/l (Tratamiento 0), 0.17 mg/l (Tratamiento 1), 0.34 mg/l (Tratamiento 2), 0.68 mg/l (Tratamiento 3), 1.36 mg/l (Tratamiento 4), y 2.72 mg/l (Tratamiento 5), en sistema semiestático. Para determinar la CL50 las dosis fueron: 3000, 3450, 3900, 4350 y 4800 mg/l de Cosmoflux® 411F. La CL50 obtenida fue de 4417.99 mg/l. En los peces se evidenció leve disminución de la actividad de nado. A la necropsia se halló palidez del hígado y acumulación de material mucoso en las branquias. Por histopatología se halló: vacuolización de hepatocitos, hiperplasia de células epiteliales, de cloro y caliciformes branquiales, vacuolización de enterocitos, aumento de centros melanomacrófagos renales, gliosis, degeneración neuronal e infiltración de células granulares eosinofílicas/células mastocitos en telencéfalo. Los hallazgos concuerdan con lo reportado en peces expuestos a surfactantes, exceptuando las lesiones del sistema nervioso central que pueden tener consecuencias sobre interacciones sociales, de alimentación y reproducción de la especie; siendo necesario profundizar la investigación sobre dicho efecto. El hígado, branquias y piel constituyen órganos blanco de la acción tóxica. La CL50 hallada (4417.99 mg/l) es alta comparada con lo reportado en surfactantes no-iónicos.

In Colombia, surfactant Cosmoflux® 411F is used for the fumigation of illicit crops in order to improve the glyphosate herbicide activity. The use of Cosmoflux® 411F is not supported by toxicological surveys. The aims of this study were to determinate the anatomopathological lesions due to the exposure to Cosmoflux® 411F and to establish lethal concentration 50 (LC50) to 96 hours in cachama blanca (Piaractus brachypomus). Juveniles of cachama blanca (40 g) in two assays were used: 1) sublethal toxicity (n= 126) and 2) determination of LC50 (n=84). Sublethal toxicity assay concentrations were: 0 mg/l (Treatment 0) 0.17 mg/l (Treatment 1), 0.34 mg/l (Treatment 2), 0.68 mg/l (Treatment 3), 1.36 mg/l (Treatment 4), and 2.72 mg/l (Treatment 5); through semi-static system. For the determination of LC50 of Cosmoflux® 411F 3000, 3450, 3900, 4350 y 4800 mg/l concentrations were used. LC50 was 4417.99 mg/l. Animals showed slight decrease in swimming activity. At necropsy examination were found paleness in liver and whitish material accumulation in top of gill filament. Histopathologically, it was found fatty degeneration and hepatocyte vacuolization, epithelial cells, chloride cells and mucous cells hyperplasia, enterocyte vacuolization, increase in the expression of melanomacrophage centres in kidney, gliosis, neuronal degeneration and infiltration of eosinophilic granule cells/mast cells in telencephalon. With exception of central nervous system lesions, the findings are according to the reported in literature about surfactant exposure in fish. Central nervous system effects can have consequences on feeding, reproductive and social interactions, due to close telencephalon/olfactory system relationship, being necessary to deep in research to these processes. In same way, liver, gills and skin are target organs of toxic action of this xenobiotic. LC50 is high (4417.99 mg/l) compared with that reported for other nonionic surfactants.

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