Associated bacterial communities of two deep-water sponges

A combination of approaches was used to examine the bacterial communities associated with 2 deep-water Scleritoderma spp. sponges. Denaturing gradient gel electrophoresis analysis of partial 16S rRNA genes extracted from sponge tissue was used to determine the structure of the sponge-associated bacterial community. Cultivation studies using a variety of marine-based media and medium additions were performed to characterize the cultivable aerobic heterotrophic bacterial community. DNA was extracted from recovered isolates, mixed, and PCR-denaturing gradient gel electrophoresis was performed to demonstrate the differences between the recoverable microorganisms and the entire bacterial community. Results indicated that, as expected, only a small fraction of the bacterial community could be cultivated and that the isolates appeared to be non-representative of sponge-associated communities for each specimen. Sequences recovered from the denaturing gel demonstrated the greatest similarity based on GenBank comparisons to uncultivated microbial associates of the lithistid sponge Theonella swinhoei and the verongid sponge Aplysina aerophoba, suggesting that the bacterial communities are similar between different host sponges from phylogenetically disparate orders.