An enzymatically modified adsorbent derived from an agro-residue mitigates the environmental risks of toxic antibiotic mixtures

Abstract

This study developed an enzymatically modified adsorbent derived from pine bark (PBEM), an agricultural residue feedstock, for the adsorptive removal of antibiotic contaminants. PBEM was synthesized by optimizing the feedstock selection and modifying it using fungal crude enzymes sustainable recoverable from natural sources. PBEM rapidly removed the antibiotics tetracycline and sulfamethoxazole from a mixed solution much more rapidly (4-99 times faster) and in higher quantities (2-5 times higher) than without enzyme modification. The outperforming removal performance was validated using adsorption kinetics and isotherm parameters over five repeated cycles. Analytical chemistry identified four novel byproducts (BPs) generated in the antibiotic mixture. Quantitative structure-activity relationship analysis revealed that two of these BPs with considerable toxicity potential comparable to the parent compounds, but they were transient and eventually removed using PBEM. As a result, PBEM effectively controlled the toxic effects of the original antibiotics and their BPs much more rapidly than the control adsorbent with no enzyme coating, as illustrated by experimental antimicrobial toxicity testing. These results thus demonstrate the potential of PBEM for both removing various antibiotic residuals via physicochemical adsorption and enzymatic breakdown and completely detoxifying solutions containing antibiotics and their BPs.