Biodegradation of gentamicin by bacterial consortia AMQD4 in synthetic medium and raw gentamicin sewage

Gentamicin, a broad spectrum antibiotic of the aminoglycoside class, is widely used for disease prevention of human beings as well as animals. Nowadays the environmental issue caused by the disposal of wastes containing gentamicin attracts increasing attention. In this study, a gentamicin degrading bacterial consortia named AMQD4, including Providencia vermicola, Brevundimonas diminuta, Alcaligenes sp. and Acinetobacter, was isolated from biosolids produced during gentamicin production for the removal of gentamicin in the environment. The component and structure of gentamicin have a great influence on its degradation and gentamicin C1a and gentamicin C2a were more prone to being degraded. AMQD4 could maintain relatively high gentamicin removal efficiency under a wide range of pH, especially in an alkaline condition. In addition, AMQD4 could remove 56.8% and 47.7% of gentamicin in unsterilized and sterilized sewage in a lab-scale experiment, respectively. And among the isolates in AMQD4, Brevundimonas diminuta BZC3 performed the highest gentamicin degradation about 50%. It was speculated that aac3iia was the gentamicin degradation gene and the main degradation product was 3'-acetylgentamicin. Our results suggest that AMQD4 and Brevundimonas diminuta BZC3 could be important candidates to the list of superior microbes for bioremediation of antibiotic pollution.