Abstract
Abstract When Pseudomonas aeruginosa PAO1 biofilms (attached to Sepharose surfaces) were subjected to dissolved Fe 3+ , most Fe was removed from solution within 25 h by surface complexation with negatively charged functional groups on the bacterial cell wall via a nucleation and mineralization process. Chemical formation of Fe-(hydr)oxides was partially responsible for dissolved Fe removal, which stemmed from a pH increase, facilitated by microbial activity. PAO1 used Fe 3+ as an electron acceptor producing Fe 2+ under localized anaerobic conditions over the first 50 h. The high ratio of Fe 2+ to total Fe in solution produced a high proportion of Fe(II) in Fe precipitates; however, as the formation of Fe-(hydr)oxides started after 50 h, the Fe 2+ content in solution began to diminish. Biofilms can so influence the local chemical conditions and metal speciation that the bulk solution phase is also affected, thereby mediating a wide-range (bio)geochemical cycling of iron. Long-term survival of natural biofilms, even under strict oligotrophic conditions, could have a broad lasting effect on the bulk geochemical environment.
Published Version
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