title: ATR-FTIR spectroscopic evidence for biomolecular phosphorus and carboxyl groups facilitating bacterial adhesion to iron oxides.
abstract: Attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy has been used to probe the binding of bacteria to hematite (α-Fe2O3) and goethite (α-FeOOH). In situ ATR-FTIR experiments with bacteria (Pseudomonas putida, Pseudomonas aeruginosa, Escherichia coli), mixed amino acids, polypeptide extracts, deoxyribonucleic acid (DNA), and a suite of model compounds were conducted. These compounds represent carboxyl, catecholate, amide, and phosphate groups present in siderophores, amino acids, polysaccharides, phospholipids, and DNA. Due in part to the ubiquitous presence of carboxyl groups in biomolecules, numerous IR peaks corresponding to outer-sphere or unbound (1400 cm(-1)) and inner-sphere (1310-1320 cm(-1)) coordinated carboxyl groups are noted following reaction of bacteria and biomolecules with α-Fe2O3 and α-FeOOH. However, the data also reveal that the presence of low-level amounts (i.e., 0.45-0.79%) of biomolecular phosphorous groups result in strong IR bands at ∼1043 cm(-1), corresponding to inner-sphere Fe-O-P bonds, underscoring the importance of bacteria associated P-containing groups in biomolecule and cell adhesion. Spectral comparisons also reveal slightly greater P-O-Fe contributions for bacteria (Pseudomonad, E. coli) deposited on α-FeOOH, as compared to α-Fe2O3. This data demonstrates that slight differences in bacterial adhesion to Fe oxides can be attributed to bacterial species and Fe-oxide minerals. However, more importantly, the strong binding affinity of phosphate in all bacteria samples to both Fe-oxides results in the formation of inner-sphere Fe-O-P bonds, signifying the critical role of biomolecular P in the initiation of bacterial adhesion.
authors.affiliation: Department of Land and, Air and Water Resources, University of California, Davis, One Shields Avenue, LAWR, Davis, CA 95616, United States. Electronic address: sjparikh@ucdavis.edu.
authors.forename: Sanjai J
authors.initials: SJ
authors.lastname: Parikh
authors.affiliation: Department of Land and, Air and Water Resources, University of California, Davis, One Shields Avenue, LAWR, Davis, CA 95616, United States.
authors.forename: Fungai N D
authors.initials: FN
authors.lastname: Mukome
authors.affiliation: Department of Land and, Air and Water Resources, University of California, Davis, One Shields Avenue, LAWR, Davis, CA 95616, United States.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000464:Alginates / Q000737:chemistry; D000596:Amino Acids / Q000737:chemistry; D001422:Bacterial Adhesion / Q000502:physiology*; D002396:Catechols / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D004926:Escherichia coli / Q000737:chemistry* / Q000502:physiology; D005290:Ferric Compounds / Q000737:chemistry*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D058085:Iron Compounds / Q000737:chemistry*; D008903:Minerals / Q000737:chemistry*; D010461:Peptones / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000502:physiology; D016958:Pseudomonas putida / Q000737:chemistry* / Q000502:physiology; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013499:Surface Properties
chemical_list: D000464:Alginates; D000596:Amino Acids; D002396:Catechols; D005290:Ferric Compounds; D006603:Hexuronic Acids; D058085:Iron Compounds; D008903:Minerals; D010461:Peptones; C017721:casamino acids; C094886:goethite; C000499:ferric oxide; D010758:Phosphorus; C001830:tryptones; D020723:Glucuronic Acid; D004247:DNA; C034221:catechol
keywords: ATR–FTIR spectroscopy; Bacterial adhesion; Biofilm; Goethite; Hematite