Phylogenetic relationships and coaggregation ability of freshwater biofilm bacteria

Nineteen numerically dominant heterotrophic bacteria from a freshwater biofilm were identified by 16S ribosomal DNA gene sequencing, and their coaggregation partnerships were determined. Phylogenetic trees showed that both distantly related and closely related strains coaggregated at intergeneric, intrageneric, and intraspecies levels. One strain, Blastomonas natatoria 2.1, coaggregated with all 18 other strains and may function as a bridging organism in biofilm development.