The release of wastewater effluents into rivers exposes river microbiomes to high loads of antibiotic resistant bacteria (ARB) along with complex mixtures of abiotic pollutants acting as stressors. To understand the proliferation of antimicrobial resistance (AMR) it is crucial to determine the factors that govern invasion of ARB into the river microbiome. Consequently, we here aim at elucidating how the resilience of resident microbiome against invasion by foreign ARB is determined by stress exposure. To achieve this, we grew natural microbial biofilms on glass slides in rivers for 1 month. Biofilms were then transferred to laboratory, recirculating flume systems and exposed to a single pulse of resistant invader bacteria (E. coli) either in presence or absence of stress induced by Cu²⁺. The invasion dynamics of E. coli into the biofilms were then monitored over time. Despite an initially successful introduction of E. coli into the biofilms, independent of the imposed stress, over time the invader perished in absence of stress. However, under stress the invading strain successfully established and proliferated in the biofilms. Noteworthy, the increased establishment success of the invader coincided with a loss in microbial community diversity under stress conditions, likely due to additional niche space becoming available for the invader. In conclusion, the intrinsic resilience of the river microbiome towards invasion by ARB is strongly linked with maintaining environmental diversity and that co-exposure to stressors that disrupt diversity increases long-term invasion success.

Primary Presenter: Uli Klümper, TU Dresden (uli.kluemper@tu-dresden.de)

Authors:

Uli Klümper, TU Dresden  (uli.kluemper@tu-dresden.de)

Kenyum Bagra, TU Dresden  ()

Xavier Bellanger, Université de Lorraine  ()

Gargi Singh, Indian Institute of Technology, Roorkee  ()

Christophe Merlin, Université de Lorraine  ()

Thomas Berendonk, TU Dresden  ()