RESUMEN
The threat of antibiotic resistant bacteria has called for alternative antimicrobial strategies that would mitigate the increase of classical resistance mechanism. Many bacteria employ quorum sensing (QS) to govern the production of virulence factors and formation of drug-resistant biofilms. Targeting the mechanism of QS has proven to be a functional alternative to conventional antibiotic control of infections. However, the presence of multiple QS systems in individual bacterial species poses a challenge to this approach. Quorum sensing inhibitors (QSI) and quorum quenching enzymes (QQE) have been both investigated for their QS interfering capabilities. Here, we first simulated the combination effect of QQE and QSI in blocking bacterial QS. The effect was next validated by experiments using AiiA as QQE and G1 as QSI on Pseudomonas aeruginosa LasR/I and RhlR/I QS circuits. Combination of QQE and QSI almost completely blocked the P. aeruginosa las and rhl QS systems. Our findings provide a potential chemical biology application strategy for bacterial QS disruption.
Asunto(s)
Antibacterianos/farmacología , Proteínas Bacterianas/farmacología , Biopelículas/efectos de los fármacos , Regulación Bacteriana de la Expresión Génica/efectos de los fármacos , Metaloendopeptidasas/farmacología , Pseudomonas aeruginosa/efectos de los fármacos , Percepción de Quorum/efectos de los fármacos , Proteínas Bacterianas/antagonistas & inhibidores , Proteínas Bacterianas/biosíntesis , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Biopelículas/crecimiento & desarrollo , Combinación de Medicamentos , Sinergismo Farmacológico , Ligasas/antagonistas & inhibidores , Ligasas/genética , Ligasas/metabolismo , Metaloendopeptidasas/biosíntesis , Metaloendopeptidasas/genética , Pruebas de Sensibilidad Microbiana , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismo , Pirimidinonas/farmacología , Percepción de Quorum/genética , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/genética , Proteínas Recombinantes/farmacología , Transactivadores/antagonistas & inhibidores , Transactivadores/genética , Transactivadores/metabolismo , Factores de Transcripción/antagonistas & inhibidores , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Triazoles/farmacologíaRESUMEN
The aim of this investigation was to evaluate the influence of batch versus continuous flow on the removal efficiencies of chemical oxygen demand (COD), nitrogen (N) and total phosphorus (TP) in tropical subsurface flow constructed wetlands (SSF CW). The quantitative role of the higher aquatic plants in nutrient removal in these two operational modes was also investigated. Results indicated no significant difference (p > 0.05) in COD removal between batch and continuous flow modes for either the planted or unplanted treatments. Furthermore, the batch-loaded planted wetlands showed significantly (p < 0.05) higher ammonium removal efficiencies (95.2%) compared with the continuously fed systems (80.4%), most probably because the drain and fill batch mode presented systematically more oxidized environmental conditions. With respect to TP removal, for both planted and unplanted beds, there was significant enhancement (p < 0.05) in batch flow operation (69.6% for planted beds; 39.1% for unplanted beds) as compared to continuous flow operation (46.8% for planted beds; 25.5% for unplanted beds). In addition, at a 4-day hydraulic retention time (HRT), the presence of plants significantly enhanced both ammonia oxidation and TP removal in both batch and continuous modes of operation as compared to that for unplanted beds. An estimation of the quantitative role of aeration from drain and fill operation at a 4-day HRT, as compared to rhizosphere aeration by the higher aquatic plant, indicated that drain and fill operation might account for only less than half of the higher aquatic plant's quantitative contribution of oxygen (1.55 g O2 per m2 per day for batch flow versus 1.13 g O2 per m2 per day for continuous flow).
Asunto(s)
Eliminación de Residuos Líquidos/métodos , Purificación del Agua/métodos , Biodegradación Ambiental , Nitrógeno/aislamiento & purificación , Oxígeno , Fósforo/aislamiento & purificación , Plantas , Clima Tropical , Movimientos del Agua , HumedalesRESUMEN
Results from a direct recharge experiment conducted in the field to investigate DOC and UVA(254) attenuation rates during the direct injection of UF treated wastewater into a artificial coastal sandfill are presented in this paper. Approximately 500 m(3) of ultra-filtered wastewater was injected into the saturated zone, over a period of 9 days. The movement of the plume was tracked over 80 days, during which time samples were obtained from multilevel samplers installed in transects across the drift axis of the plume. An analysis of fluorescein in the samples obtained during the drift of the UF plume showed that DOC and UVA were attenuated beyond rates predicted by conservative mixing, by up to a maximum of 45%. A degradation coefficient of 0.0175 day(-1) was found to be applicable for DOC degradation. After a drift period of 80 days, DOC and UVA reduced to approximately 4.5 mg/l and 0.100 cm(-1), respectively, from initial values of 8.06 mg/l and 0.199 cm(-1).