Efficacy of antimicrobial copper surfaces under spaceflight conditions: Preliminary results of the BIOFILMS experiment

Abstract

Biofilms are a significant challenge in environments such as hospitals and industrial facilities, but also in space environments. Microbial induced corrosion due to biofilm formation, biofouling and clogging of pipes are serious threats to the integrity of spacecraft. In addition, biofilms can harbor and act as reservoirs for opportunistic pathogenic microorganisms, which could pose a threat to astronaut health, especially since astronauts exhibit a compromised immune system during spaceflight. Antimicrobial surfaces are one of many mitigation strategies against microbial biofilm formation. Copper has been known for its antimicrobial properties since ancient times, and additional surface modification using Direct Laser Interference Patterning (DLIP) has been shown to increase antibacterial efficacy. However, the interplay between cells, their environment and surfaces under space conditions requires further investigation, as fluid dynamics, mass transport and sedimentation are different in microgravity. The BIOFILMS experiment was selected by the European Space Agency (ESA) to test antimicrobial coppercontaining surfaces against bacterial adhesion and biofilm under reduced gravity conditions on the International Space Station (ISS). The BIOFILMS experiment included three flights to the ISS from August 2021 to March 2023, during which the bacterial model organisms Staphylococcus capitis, Cupriavidus metallidurans, and Acinetobacter radioresistens were incubated on various surfaces inside specially designed hardware to ensure a controlled environment. Preliminary results show no negative effect of reduced gravity on the antimicrobial efficacy of copper and no clear effect of gravity conditions on adhesion and biofilm formation on the reference stainless steel surfaces. The final results of the project will provide valuable insights into selecting suitable surfaces and functionalization techniques to reduce biofilm formation, increase safety, and improve the sustainability of space travel.