Novel antibiotic resistance genes from Stenotrophomonas maltophilia and Chryseobacterium sp. of soil origin discovered by functional gene library

Abstract

Background: As the most diverse habitat of microorganisms, soil has also been recognised as a reservoir of both antibiotics and the antibiotic resistance genes (ARGs). The bacteria naturally inhabiting the soil or water often possess the innate ARGs to counteract the chemical compounds produced by competitors living in the same environment. Stenotrophomonas maltophilia is an ubiquitous environmental bacterium, also associated with an increasing number of nosocomial infections. Chryseobacterium sp. found primarily in soil and water and is increasingly found to colonize the immunocompromised patients through contaminated medical devices and liquids. Both bacteria have high innate resistance to antibiotics, which complicates the treatment of their infections. Objectives: We have recently collected antibiotic resistant bacteria from agricultural soils, Stenotrophomonas sp. and Chryseobacterium sp. being among the most antibiotic resistant bacteria selected. We aimed to select the ARGs responsible for their innate resistance by generating and screening functional gene libraries. Methods: Genomic DNA was isolated from S. maltophilia and Chryseobacterium sp. resistant to at least 2 classes of antibiotics. gDNA was fragmented and used to create functional DNA fragment libraries, which were transformed to E. coli and screened for antibiotic (beta-lactams, aminoglycosides, quinolones) resistant clones.