RESUMEN
Standard methods of microbial cultivation only enable the isolation of a fraction of the total environmental bacteria. Numerous techniques have been developed to increase the success of isolation and cultivation in the laboratory, some of which derive from diffusion chambers. In a diffusion chamber, environmental bacteria in agar medium are put back in the environment to grow as close to their natural conditions as possible, only separated from the environment by semi-permeable membranes. In this study, the iChip, a device that possesses hundreds of mini diffusion chambers, was used to isolate tributyltin (TBT) resistant and degrading bacteria. IChip was shown to be efficient at increasing the number of cultivable bacteria compared to standard methods. TBT-resistant strains belonging to Oceanisphaera sp., Pseudomonas sp., Bacillus sp. and Shewanella sp. were identified from Liverpool Dock sediment. Among the isolates in the present study, only members of Pseudomonas sp. were able to use TBT as a sole carbon source. It is the first time that members of the genus Oceanisphaera have been shown to be TBT-resistant. Although iChip has been used in the search for molecules of biomedical interest here we demonstrate its promising application in bioremediation.
Asunto(s)
Compuestos de Trialquiltina , Contaminantes Químicos del Agua , Bacterias , Biodegradación AmbientalRESUMEN
The effect of promethazine on peroxidase-catalyzed oxidation of 3,3', 5,5'-tetramethylbenzidine was investigated at pH 5.4. Promethazine dose dependently introduced a lag in the appearance of tetramethylbenzidine charge-transfer complex monitored at 652 nm. Increasing concentrations of tetramethylbenzidine however decreased the lag period proportional to the tetramethylbenzidine concentration. Addition of promethazine to preformed charge transfer complex caused rapid bleaching of the blue-colored complex. Titration of promethazine with the yellow-colored diimine gave rise to the blue charge-transfer complex and the complete reduction of the species to the colorless parent amine compound. The available evidence suggests that promethazine is oxidized via redox mediation by tetramethylbenzidine peroxidase-oxidized products.