Adhesion potential of bacteria isolated from tap water to several materials using a modified microtiter-plate test

Abstract

Autochthonous heterotrophic aerobic bacteria from drinking water were isolated, identified by growth on selective media, biochemical tests and 16S rDNA gene sequence. From 25 different isolated bacteria, 8 representative bacteria were selected in order to test their adhesion ability to four different support materials. The bacteria selected were Acinetobacter calcoaceticus, Burkholderia cepacia, Methylobacterium sp., Mycobacterium mucogenicum, Sphingomonas capsulata, Staphylococcus sp., Stenotrophomonas maltophilia and the materials used for adhesion were stainless steel ASI 316 (SS), polyethylene (PE), polyvinyl chloride (PVC) and polystyrene (PS). Strain variation on adherence ability was assessed by using two distinct strains of Sph. capsulata (sp. 1 and sp. 2) and S. maltophilia (sp.1 and sp. 2). The adhesion assays were performed during 2 h using a modified microtiter-plate test. The results obtained revealed that the bacteria adhered in a higher extent to PE (P < 0.05), with the exception of Methylobacterium sp. (higher colonization of SS) and Staphylococcus sp. (higher colonization of PS). Strong and moderate adherence were detected for A. calcoacticus and Staphylococcus sp. - adhered to the four materials used, while only Sph. capsulata sp. 1 was non-adherent to the tested materials. Furthermore, it is expected that some of the strong and moderately (A. calcoaceticus, Staphylococcus sp. and S. maltophilia sp. 1) adherent bacteria will play a determinant role in the primary colonization of the surfaces. The use of distinct S. maltophilia and Sph. capsulata strains showed the existence of varying ability of adherence for the distinct strains, demonstrating that no strain can effectively represent its species. This study provides information about a rapid and reliable methodology for bacteria adherence ability assessment and gives useful clues about the behaviour of drinking water autochthonous bacteria when exposed to potential adhesion surfaces.