Bacterial primary colonization and early succession on surfaces in marine waters as determined by amplified rRNA gene restriction analysis and sequence analysis of 16S rRNA genes

Abstract

The nearly universal colonization of surfaces in marine waters by bacteria and the formation of biofilms and biofouling communities have important implications for ecological function and industrial processes. However, the dynamics of surface attachment and colonization in situ, particularly during the early stages of biofilm establishment, are not well understood. Experimental surfaces that differed in their degrees of hydrophilicity or hydrophobicity were incubated in a salt marsh estuary tidal creek for 24 or 72 h. The organisms colonizing these surfaces were examined by using a cultivation-independent approach, amplified ribosomal DNA restriction analysis. The goals of this study were to assess the diversity of bacterial colonists involved in early succession on a variety of surfaces and to determine the phylogenetic affiliations of the most common early colonists. Substantial differences in the representation of different cloned ribosomal DNA sequences were found when the 24- and 72-h incubations were compared, indicating that some new organisms were recruited and some other organisms were lost. Phylogenetic analyses of the most common sequences recovered showed that the colonists were related to organisms known to inhabit surfaces or particles in marine systems. A total of 22 of the 26 clones sequenced were affiliated with the Roseobacter subgroup of the alpha subdivision of the division Proteobacteria (alpha-Proteobacteria), and most of these clones were recovered at a high frequency from all surfaces after 24 or 72 h of incubation. Two clones were affiliated with the Alteromonas group of the gamma-Proteobacteria and appeared to be involved only in the very early stages of colonization (within the first 24 h). A comparison of the colonization patterns on the test surfaces indicated that the early bacterial community succession rate and/or direction may be influenced by surface physicochemical properties. However, organisms belonging to the Roseobacter subgroup are ubiquitous and rapid colonizers of surfaces in coastal environments.

FIG. 1

Dendrogram resulting from a hierarchical clustering analysis of the bacterial community structures of the 12 clonal libraries constructed with Ward linkages.

FIG. 2

Phylogenetic tree showing the relationships among the 22 cloned sequences in the Rhodobacter group. The tree was constructed by using the maximum-parsimony method. The distancnes represent the numbers of nucleotide substitutions per homologous sequence site. Percentages of 100 bootstrap resamplings in the maximum-parsimony analysis are shown above nodes, and bootstrap values that supported certain cluster patterns generated by neighbor-joining analysis (to the left of the vertical line) and maximum-likelihood analysis (to the right of the vertical line) are shown below nodes. Bootstrap values less than 50% are not shown.