Bacterial community composition based on 16S rRNA gene analyses of the four bubble biofilm samples. BB 1, BB 2, BB 3 and BB 4 correspond to NCBI sample accession numbers SAMN11898234, SAMN11898235, SAMN11898230 and SAMN11898229, respectively. Percentages show the relative abundance of the bacterial community based on the frequency of bacterial 16S rRNA in each samle. Taxonomic assignment is made at family level.