Bianca Serrano-Torres, Karleen M. González-Rosario, Christian D. Del Valle-Colón and José R. Pérez-Jiménez
Xylene is an aromatic organic compound formed by two methyl groups and a benzene ring in the center that can cause health complications. This chemical is used in many industries and it is one of the main components in gasoline. Because of this, exposure to this contaminant is very probable. Bacteria, such as Pseudomonas putida, are capable of degrading xylene. The objective of this study is to isolate and characterize bacteria that are also capable of degrading this benzene derivative. Samples were obtained from different ecosystems across Puerto Rico. They were cultivated on general media initially and pure strains where tested on a mineral medium with xylene as its sole carbon source. Putative xylene degraders where characterized by Gram stain, catalase test, CHROMagar and 16S rRNA gene sequencing. The catalase test revealed that all of the bacteria samples are catalase positive. A total of 19 bacteria grew in the mineral medium. The percentages obtained by the gene sequencing don’t allow the exact characterization of the bacteria. In the CHROMagar petri dishes the possibility of two bacteria being Pseudomonas, one of them being Klebsiella, Enterobacter or Citrobacter and one of them being Eschericia coli was observed. Nevertheless, in the gram stain test all of the bacteria resulted to be gram positive. The gram stain results contradict the results of the CHROMagar dishes, therefore, these techniques may have to be repeated in the future.