Degradación de tetraciclina a partir de bacterias aisladas de aguas residuales de origen hospitalario

Abstract

Although it has been demonstrated that there are abiotic processes that can transform tetracycline (TC), it has been shown that microbial processes can degrade TC in the aquatic environment. This work evaluated the percentage of TC degradation by isolating resistant bacteria from wastewater from a hospital in Quito. Two resistant bacteria were isolated through serial dilutions and plate striations. From the isolated bacteria, we proceeded to a presumptive characterization by macroscopic and microscopic evaluation (Gram stain). Likewise, for secondary identification of the bacteria, a battery of biochemical tests called IMVIC was applied. Antimicrobial sensitivity was evaluated through disc-plate antibiograms and, finally, the residual concentration of CT was quantified by HPLC. Two resistant bacterial strains were identified: Klebsiella pneumoniae (CB1) and Escherichia coli (CB2). Only strain CB1 was used for the experiments because it presented greater resistance to CT. The percentage of CT biotransformation by strain CB1 was measured on day 4 at pH 7.2 and a temperature of 30 °C. Strain CB1 degraded 79% and 81% of the initial concentration of CT in treatments T1 and T2, respectively, after 4 days. The results obtained in this work can provide a theoretical basis for estimating the degradation of antibiotics such as CT in the aquatic environment and the potential use of the strain in the design of engineered processes to remove tetracycline from water.