Microbiologically Influenced Corrosion of Aerospace-Grade Aluminum by SRB-Enriched Biofilms Isolated from the Mars Analog Lake Salda.

Lake Salda in Türkiye serves as a valuable Earth analog for studies of the properties of Mars due to its mineralogical and microbiological similarities to Jezero Crater on Mars. This study investigated the role of sulfate-reducing bacteria (SRB) enrichment culture isolated from Lake Salda on the microbiologically influenced corrosion (MIC) of an aluminum alloy (AA7075) using electrochemical, microbiological, molecular, and spectroscopic methods. Potentiodynamic polarization (PDP) tests confirmed SRB-enriched biofilm significantly accelerated corrosion. Fourier Transformed Infrared Spectroscopy (FTIR) further distinguished the control and biotic surfaces, showing the replacement of a 980 cm-1 polysaccharide band with a 1075 cm-1 cyclic polysaccharide vibration in SRB-colonized coupons. This spectral transition reflects biofilm maturation and EPS accumulation, providing molecular evidence for SRB-driven MIC. Molecular analysis identified Proteobacteria and Firmicutes as dominant phyla, and Desulfofustis limnaeus was detected in Lake Salda for the first time. Moreover, benthic foraminifera and ostracods were observed, some with morphological anomalies. These results provide mechanistic insight into the biochemical and electrochemical interactions driving SRB-induced corrosion, highlighting Lake Salda's importance for studying microbial-material interactions in extreme environments.