In Vitro Biodegradation of Gliclazide by Aeromonas hydrophila and Serratia odorifera Bacteria

Abstract

Gliclazide is a pharmaceutical product used in the treatment of type 2 diabetes. However, this drug is considered to be highly undesirable when present in the environment. We tested in vitro the biodegradation of gliclazide as the sole source of carbon and energy by a microbial consortium. After a 5-month adaptation period in batch culture, two bacterial strains were isolated and identified, namely, Aeromonas hydrophila and Serratia odorifera. With an initial concentration of gliclazide at 0.5 g/L, these two bacteria and their combined culture degraded gliclazide with a specific activity of 22.3, 24.1, and 19.2 ng/(mg·h) and a yield of 88.88%, 82.94%, and 95.88%, respectively. Experimental results reveal a removal efficiency of 98.904% at an inlet concentration of 5 g/L and a flow rate of 14 L/h. The maximum removal efficiency of the biotrickling filter was 99.6%, at a gliclazide inlet concentration of 0.5, 1, and 5 g/L and a flow rate of 6.3 L/h. Interestingly, it was observed that after a period of 12 months, the two dominant strains differed from those present in the initial inocula. Thus, the high elimination efficiencies obtained in this study reveal the interest of the use, for the first time, of a biotrickling filter for the study of the biodegradation of gliclazide. Obtaining a microbial consortium strongly adapted to this substrate may prove to be an interesting alternative for a possible application in the treatment, before discharge, of wastewater containing this molecule or other related molecules, especially in the pharmaceutical industry.