Differences between <i>A</i><i>. t</i><i>hiooxidans</i> and <i>A</i><i>. </i><i>ferrooxidans</i> Biofilms Formed on Concrete and Stoneware

Abstract

Sulfur-oxidizing bacteria (SOB) of Acidithiobacillus genus, especially of A. thiooxidans and A.ferrooxidans species are considered as very aggressive biological factors that influences deterioration of many materials, including mineral building materials like concrete and stoneware. Biofilms formed by these bacteria play a significant role in microbiologically influenced corrosion (MIC) of various materials in conditions that ensure sufficient moisture. The aim of this work was to assess differences between A. thiooxidans and A. ferrooxidans biofilms formed on concrete and stoneware. Both strains were prone to form biofilms on concrete and stoneware. However, the type of mineral materials strongly influenced metabolic activities of the tested strains, thus providing to formation of biofilms displaying different features. The higher activities of cells were observed in biofilms of A.ferrooxidans bacteria. The higher total biomass attached to the material surface as well as concentration of proteins in liquid culture medium were observed in biofilms grown on concrete samples. The optimal time of biofilm growth on tested materials was 48 hours on concrete, and 72 hours on stoneware. Amongst materials tested, concrete samples were more susceptible to corrosion in the presence of A. thiooxidans and A. ferrooxidans bacteria.