Testing Laser-Structured Antimicrobial Surfaces Under Space Conditions: The Design of the ISS Experiment BIOFILMS

Katharina Siems,Jutta Krause,Daniel W Müller,Rocco L Mancinelli,Nicol Caplin,Michael Laue,Marco Vukich,Rene Demets,Alessandra Tortora,Ralf Moeller,Christian Roesch,Rob Van Houdt,Aisha Ahmed,Ralf Kautenburger,Laurens Maertens,Frank Mücklich,Kristina Brix,Gudrun Holland,Sandra Baur

doi:10.3389/frspt.2021.773244

Abstract

Maintaining crew health and safety are essential goals for long-term human missions to space. Attaining these goals requires the development of methods and materials for sustaining the crew’s health and safety. Paramount is microbiological monitoring and contamination reduction. Microbial biofilms are of special concern, because they can cause damage to spaceflight equipment and are difficult to eliminate due to their increased resistance to antibiotics and disinfectants. The introduction of antimicrobial surfaces for medical, pharmaceutical and industrial purposes has shown a unique potential for reducing and preventing biofilm formation. This article describes the development process of ESA’s BIOFILMS experiment, that will evaluate biofilm formation on various antimicrobial surfaces under spaceflight conditions. These surfaces will be composed of different metals with and without specified surface texture modifications. Staphylococcus capitis subsp. capitis, Cupriavidus metallidurans and Acinetobacter radioresistens are biofilm forming organisms that have been chosen as model organisms. The BIOFILMS experiment will study the biofilm formation potential of these organisms in microgravity on the International Space Station on inert surfaces (stainless steel AISI 304) as well as antimicrobial active copper (Cu) based metals that have undergone specific surface modification by Ultrashort Pulsed Direct Laser Interference Patterning (USP-DLIP). Data collected in 1 x g has shown that these surface modifications enhance the antimicrobial activity of Cu based metals. In the scope of this, the interaction between the surfaces and bacteria, which is highly determined by topography and surface chemistry, will be investigated. The data generated will be indispensable for the future selection of antimicrobial materials in support of human- and robotic-associated activities in space exploration.

Highlights

An enduring human presence in space is required to achieve the primary goals of space programs worldwide
We only considered bacteria that are classified in the lowest risk group to eliminate possible health risks in the unlikely event of exposure
For the onboard storage of the bacteria inside the BIOFILMS hardware phosphate buffered saline (PBS) was selected to ensure there is an osmotic balance between the bacterial cells and the ambient medium

Summary

Introduction

An enduring human presence in space is required to achieve the primary goals of space programs worldwide. As longer human missions, (e.g., to Moon and Mars) are being planned for the foreseeable future, the optimization of isolated self-sustaining habitats is of prime importance. One key aspect in this regard is extensive microbial control. The ubiquity of microorganisms in crewed spacecrafts such as the International Space Station (ISS) poses several critical risks to astronauts as well as to structural spacecraft materials. Decreasing unwanted microbial growth and biofilm formation within a space craft will aid in inhibiting forward and backward contamination of extraterrestrial systems as for improved adherence to planetary protection protocols. Microorganisms have shown unparalleled potential for regenerative life support systems, such as MELiSSA, which has been designed to enable long-term manned missions in space (Lasseur et al, 2010)

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Results

Conclusion