Bracho Rincón, Dina P.

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    Degradación de p-Nitrofenol por bacterias en los ríos Añasco y Guanajibo y la Quebrada de Oro (Puerto Rico)
    (2007) Bracho Rincón, Dina P.; Zaidi, Baqar R.; College of Arts and Sciences - Sciences; Montalvo, Rafael; Alfaro Lozano, Mónica; Department of Biology; Otero Morales, Ernesto
    Biodegradation of p-nitrophenol and changes in bacterial communities during degradation process in water samples from the Añasco and Guanajibo rivers and Quebrada de Oro were determined. The degradation rate of p-nitrophenol was monitored spectrophotometrically. The numbers of p-nitrophenol degrading and heterotrophic bacteria were estimated by most probable number (MPN). Analysis of the changes of the bacterial communities during degradation of p-nitrophenol was done using Terminal Restriction Fragment Length Polymorphisms (T-RFLP) of gene 16S rDNA from Añasco River and Quebrada de Oro samples. In all sampling sites, pnitrophenol degradation was over 90%; however degradation was generally higher in Añasco and Guanajibo River but varied with each sampling month. For example, in Añasco in November the degradation was in 34.3 h, in February 48.3 h and in April 85.0 h. The variability could be due to the changes in environmental conditions as well as changes in PNP-degrading bacterial populations. The numbers of p-nitrophenol degrading bacteria were also higher in samples from Añasco and Guanajibo River, resulting in faster degradation. This could be due higher anthropogenic input of toxic chemicals at these sites; this may result in increased number of degrading bacteria. The T-RFLP analysis showed that the variations in the Añasco River and Quebrada Oro microbial community structures are greater in the communities exposed to pnitrophenol. It also showed that the change was more noticeable when the degradation reaches the 50%. This may be associated with an increase in the degrading bacterial populations. Sequence analysis of 16s rDNA from the isolated degrading bacteria showed close relationship with the genus Pseudomonas. This genus is characterized by organisms with wide metabolic diversity, and has been widely isolated from environment exposed to variety of toxic chemicals.