Biofilm formation causes surface changes to stainless steel

Bacteria microfilms, or biofilms, can damage not only biological surfaces, but also non-biological ones by causing corrosion and pitting. Zanna et al. studied the formation of biofilms composed of marine Pseudoalteromonas on stainless steel surfaces in artificial sea water.

The authors focused on the first hour of adhesion and monitored the experiment using epifluorescence microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS). For comparison, the experiment was performed using artificial sea water with and without nutrients added in.

“Time of flight ion mass spectrometry 3D chemical maps allowed us to distinguish areas covered from those not covered by the bacteria. We were then able to characterize distinctively the stainless composition and the organic layer,” said author Sandrine Zanna.

By using XPS and ToF-SIMS, the authors characterized the composition of proteins and polysaccharides during biofilm formation. They found that the inclusion of nutrients did not significantly impact the protein and polysaccharide composition of the biofilm, which was primarily composed of proteins.

In addition, the authors discovered that the surface composition of the stainless steel was modified during the first stages of bacterial adhesion. Its surface became enriched with chromium, due to increased bacterial activity which caused bacteria-oxide interactions.

Building upon this research, the authors intend on increasing bacteria exposure time to follow changes induced by bacterial activity on stainless-steel surfaces to better understand the more advanced stages of biocorrosion.

Source: “Early stage of marine biofilm formation on duplex stainless steel,” by Elise Gardin, Sandrine Zanna, Antoine Seyeux, Dimitri Mercier, Audrey Allion-Maurer, and Philippe Marcus, Biointerphases (2020). The article can be accessed at https://doi.org/10.1116/6.0000361 .