Biofilm (IMAGE) Arizona State University Caption Biofilms are dense, multispecies aggregates of cells, which clump together in a residue that forms on surfaces. Biofilms are resistant to antimicrobials and notoriously difficult to clean up. They can cause a range of health issues and have a corrosive effect on many materials, including stainless steel, making them a threat to the water supply system of the ISS. Credit The Biodesign Institute at Arizona State University Usage Restrictions None License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.