Caracterización de cepas bacterianas aisladas a partir de suelos, con potencial para degradar PCB’s presentes en aceites dieléctricos provenientes de la Central Hidroeléctrica “Alao” de la Empresa Eléctrica Riobamba S.A

Abstract

The purpose of this research was to characterize bacteria strains with the potential to degrade PCB’s present in dielectric oils. To this end bacteria was isolated from soil sample from the “Alao” Hydroelectric Center, using three different cultivation methods: Standard Methods Agar, PAS and Mm, each one supplemented with 25 µL of oil contaminated with 43,6 ppm of PCB’s. Nineteen bacterial colonies were isolated and subsequently subjected to a higher concentration of PCB’s. Eighteen colonies were able to withstand 250 µL of oil contaminated with 500 ppm of PCB’s. Once purified these were characterized according to their microscopic and macroscopic traits and tolerance to heavy metals. Through biochemical testing, 18 strains were identified belonging to the species Providencia alcalifaciens, Proteus mirabillis, Providencia rettgeri, Providencia stuartii, Pseudomona alcaligenes, Morganella morganii y Shigella disenteriae. Three strains were selected to evaluate their ability to degrade PCB’s: Pseudomona alcaligenes, Providencia rettgeri, Providencia stuartii. Each strain was dosed in an experimental matrix composed strategically of PCB’s contaminated oil on sand, to increase the contact surface between the bacteria and the contaminant. Pseudomona alcaligenes achieved a 33% reduction in PCB’s, following by Providencia rettgeri with 26% and finally Providencia stuartii with 12 %, all in a period of 42 days. Based on these results, it was concluded that it was possible to find in our midst bacteria capable of biodegrading PCB’s, making way for studies that seek to apply this method on a larger scale. It is recommended to realize researches than aim to enhance the degradation of PCB’s through the use of any the bacteria found.