0009) (Fig. 3a and b). Although it was not the focus of the study, differences in bacterial community structures between the two sampling locations were examined to
determine if the T-RFLP method is able to detect differences among bacterial Midostaurin cell line assemblages that are assumed to be due to differences in water quality. A PCA clearly separated the bacterial assemblages between the two locations and the two sampling times (Fig. 4). Replicates from each location were more variable during summer than winter, and more variable offshore than inshore (Fig. 4). This result was confirmed using anosim, which revealed significant differences between locations (R = 0.544, P = 0.0177) and sampling times (R = 0.299, P < 0.0001). The length of the species-vectors in the PCA biplot and a SIMPER analysis consistently indicated that T-RFs representing the Roseobacter clade (Roseobacter and Silicibacter), Erythrobacter, Hyphomonas, Gammaproteobacteria and diatom plastids contributed mostly to the dissimilarities (54.9%) between substrates at different seasons and locations (Fig. 1) and between locations and sampling times despite substrate type (Fig. 4). Overall, 37 T-RFs were identified, of which, 89.2% could be assigned to clones that were taxonomically identified from the clone libraries (within ±0.5 bp) (Supporting Information Table S1), and thus could be assigned
to a bacterial taxon. All T-RFs detected were Selleck Tamoxifen present in the glass slide profiles. T-RFLP, cloning and sequencing of 16S rRNA genes revealed that coral reef-associated biofilms comprised of complex bacterial Oxymatrine and microalgal communities. Relatively
similar, although not always identical bacterial community structures were present on different substrate types over two sampling times (during a summer and a winter). Bacterial community composition on reef sediments differed significantly from the other substrate types at the inshore location that was influenced by pronounced changes in water quality during different seasons. Reef sediments also showed the largest variability in bacterial community composition among all investigated substrates. This suggests that reef sediments may have low reproducibility and is therefore not suitable for bioindicator studies in coral reefs in comparison to other more ideal substrates. Relatively variable bacterial community compositions were also identified on ceramic tiles in comparison to the other substrates during winter, suggesting that ceramic tiles are also not ideal substrates for bacterial biofilm bioindicator studies. In contrast, glass slides and coral skeletons substrates produced comparably stable and highly reproducible community compositions independent of sampling time and/or location. Another aspect of substrate choice is the practical requirement for a simple method for the removal of total and/or near complete biofilm biomass from the actual substrate.