Alterations in extracellular substances during the biofilm development of Pseudomonas aeruginosa on aluminium plates

The chemical moieties during biofilm formation of Pseudomonas aeruginosa on aluminium plates were examined for a period of 17 days. The effect of flui d shearing upon biofilm formation has also been investigated. The Fourier t ransform infrared (FTIR) spectrum of the biofilm taken on the fifth day sho wed significant differences compared with the spectrum of the unattached ba cterial cells, indicating that structural changes or modifications of the c ell envelope had taken place during the development of the biofilm. Major c hanges were also observed in the spectrum during the subsequent development of the biofilm from day 5 to day 17. The increasing intensity of a band co rresponding to the symmetric stretching mode of the carboxyl group indicate d interactions between the carboxyl group and the aluminium surface. Increa sed bacterial colonization was also observed at the air-water interface of the aluminium plates when compared with the middle and the bottom parts. Ch anges in FTIR spectra of the biofilm at the bottom, at the middle, and at t he air-water interface suggest that the mechanisms of bacterial attachment differed by a -COO- interaction at the air-water interface, and by both -CO O- and NH3+ groups beneath the water surface.