Implementing sponge physiological and genomic information to enhance the diversity of its culturable associated bacteria

Abstract

In recent years new approaches have emerged for culturing marine environmental bacteria. They include the use of novel culture media, sometimes with very low-nutrient content, and a variety of growth conditions such as temperature, oxygen levels, and different atmospheric pressures. These approaches have largely been neglected when it came to the cultivation of sponge-associated bacteria. Here, we used physiological and environmental conditions to reflect the environment of sponge-associated bacteria along with genomic data of the prominent sponge symbiont Candidatus Poribacteria sp. WGA-4E, to cultivate bacteria from the Red Sea sponge Theonella swinhoei. Designing culturing conditions to fit the metabolic needs of major bacterial taxa present in the sponge, through a combined use of diverse culture media compositions with aerobic and microaerophilic states, and addition of antibiotics, yielded higher diversity of the cultured bacteria and led to the isolation of novel sponge-associated and sponge-specific bacteria. In this work, 59 OTUs of six phyla were isolated. Of these, 22 have no close type strains at the species level (< 97% similarity of 16S rRNA gene sequence), representing novel bacteria species, and some are probably new genera and even families.

Keywords: Porifera; Theonella swinhoei; bacterial cultivation; sponge-specific cluster; symbionts.