Biodegradation of the antiviral tenofovir disoproxyl by a cyanobacteria/bacteria culture.

Abstract Tenofovir disoproxil fumarate (TDF) is an antiretroviral drug extensively used by people living with HIV/AIDS. TDF molecule is hydrolysed in vivo and liberate the tenofovir, the active part of the molecule. Tenofovir is a very stable drug and the discharge of its residues into the environment can potentially lead to risk for aquatic species. This study evaluated the TDF biodegradation and removal by cultures of Microcystis novacekii, non axenic, it presented the bacteria Pseudomonas pseudoalcaligenes associated. Concentrations of TDF 12.5, 25.0 and 50.0 mg.L-1 were used to the tests. The process occurred in two stages. In the first 72 hours, TDF was de-esterified, forming the tenofovir monoester intermediate by abiotic and enzymatic process associated in extra cell medium. In a second step, the monoester was removed from the culture medium by intracellular processes. At the end of the experiment 88.7 to 94.1% of TDF and its monoester derivative were removed from the culture medium over 16 days. This process showed higher efficiency to the TDF removal at the concentration 25 mg.L-1. The tenofovir or others by-products of TDF were not observed in the test conditions. Tenofovir isoproxil monoester has partial antiviral activity and has shown to be persistent, maintaining a residual concentration after 16 days, indicating the need to continue the research on methods of this product total removal from the aquatic environment.