P139: Degradation of Antibiotics in Wastewater Using Rhizospheric Bacteria Recovered from an Invitro Hydroponic Phytoremediation System

Wastewater treatment processes typically do not effectively remove antibiotics hence release these compounds into the environment, which poses a potential threat to human health. In our lab, a hydroponic remediation system has been developed using vetiver grass (Chrysopogon zizanoides L. Nash) to mitigate tetracycline (TC) contamination from wastewater.  The goal of this study is to determine the role(s) of rhizospheric bacteria in the degradation of TC in this plant-based treatment system.  TC-tolerant bacteria were recovered from vetiver roots and contaminated water during the 30-day period of remediation using viable count technique on R2A medium+ different levels of TC (10, 25, 50 and 100 ppm).  Ten TC-tolerant bacterial isolates were selected for further study.  The pure cultures were transferred to a minimal medium (MSM) with TC as the sole carbon/energy source at different levels of TC (10, 25, 50 and 100 ppm), for enrichment studies.  Results were analyzed using a spectrophotometer, plate reader and HPLC. Direct count techniques were performed every 24 hours to measure the numbers of cells present.  DNA extraction and RT- PCR were performed on the selected isolates and 16S rRNA sequences were evaluated to assess the bacterial communities to which these TC tolerant bacteria belong.  Phospholipid fatty acid analysis was also performed on these isolates.  HPLC and growth study results indicate that some of these TC-tolerant bacteria can use TC as their sole carbon source.  These bacteria transform TC into its isomers anhydro-TC, epi-TC and other unknown metabolites establishing their role in TC degradation in water systems.