Conclusion
Bacillus subtilis biofilms were cultivated at Fe2+ inflow concentrations of 0.25 and 2.5 mg/L, respectively, as well as at wall shear stress levels of 0.05 and 0.27 Pa, respectively. Structure development was successfully monitored by means of optical coherence tomography and quantified by a large set of ten structural parameters. Through analysis of ten replicates the following conclusions are drawn:
  1. Iron is - independently of its concentration - incorporated and accumulated within the biofilm matrix as modifications of FeO(OH).Bacillus subtilis biofilms cultivated in this study showed the accumulation of α- and β-FeO(OH).
  2. FeO(OH) seems to provide cross-linking abilities and may thrive EPS production enhancing the adhesive as well as cohesive strength of investigated biofilms.
  3. A positive correlation between the Fe2+ inflow concentration and biofilm development/accumulation partially compensates increased detachment of biofilm at elevated wall shear stress levels.