Insignificant Impact of Chemotactic Responses of Pseudomonas aeruginosa on the Bacterial Attachment to Organic Pre-Conditioned RO Membranes

Abstract

We investigated the impact of conditioning compositions on the way bacteria move and adhere to reverse osmosis (RO) membranes that have been pre-conditioned by organic compounds. We used humic acid (HA), bovine serum albumin (BSA), and sodium alginate (SA) to simulate conditioning layers on the RO membranes. First, we investigated the chemotactic responses of Pseudomonas aeruginosa PAO1 to the organic substances and the impact of changes in physicochemical characteristics of pre-conditioned membranes on bacterial attachment. Second, we observed bacterial attachment under the presence or absence of nutrients or microbial metabolic activity. Results showed that there was no relationship between the chemotactic response of P. aeruginosa PAO1 and the organic substances, and the changes in hydrophobicity, surface free energy, and surface charge resulting from changing the composition of the conditioning layer did not seem to affect bacterial attachment, whereas changing the roughness of the conditioned membrane exponentially did (exponential correlation coefficient, R2 = 0.85). We found that the initial bacterial attachment on the membrane surface is influenced by (i) the nutrients in the feed solution and (ii) the microbial metabolic activity, whereas the chemotaxis response has a negligible impact. This study would help to establish a suitable strategy to manage bacterial attachment.

Towards a better understanding of the effect of protein conditioning layers on microbial adhesion: a focused investigation of fibronectin and bovine serum albumin layers on SiO2 surfaces

“…The positive impact of the surface roughness on bacterial adhesion has been demonstrated in several studies although the reported outcomes remain contradictory and are shown to be dependent on the bacterial species as well as on the experimental conditions. 58–61…”

“…The positive impact of the surface roughness on bacterial adhesion has been demonstrated in several studies although the reported outcomes remain contradictory and are shown to be dependent on the bacterial species as well as on the experimental conditions. [58][59][60][61] Concerning the PF-QNM surface topography of P. aeruginosa PAO1-Tn7-gfp adhered to the SiO 2 surface conditioned with a BSA layer, resulting from a solution with a protein concentration of 10.0 µM, the bacteria display a tendency to burrow into the BSA layer, thus modifying its local organization and rendering the bacterial flagella undiscernible in the contrary to the BSA layer obtained from solution with a lower protein concentration (0.75 µM) (Fig. 7b and c).…”