80 Effects of Carbon Sources on Secondary Metabolite Production in Teredinibacter turnerae

Faculty Mentor: Eric Schmidt (Medicinal Chemistry, University of Utah)

Shipworms are wood-digesting marine bivalves that rely upon symbiotic bacteria for cellulose digestion. The symbiotic bacteria, which grow intracellularly in shipworm gill tissue, produce cellulases that are then transported to the shipworm’s cecum. It has also been hypothesized that the bacteria produce antibiotics, exported to the cecum with the cellulases, to prevent microbial glucose scavenging upon cellulose digestion, thus making the bacteria medicinally interesting. While various species of bacteria can form symbioses with shipworms, the most well-characterized is Teredinibacter turnerae, in part due to the success of in-lab culturing. Nonetheless, the lab growth conditions are significantly different from the in situ environment, as the physical conditions of intracellular growth are incredibly difficult to replicate with flask or fermenter culturing and the chemical conditions would require complex and potentially expensive media.

Since physical and chemical growth conditions both affect microbial metabolism, these conditions also affect growth patterns and secondary metabolite production. To investigate these effects, various growth conditions (such as presence of cytosolic compounds and carbon source, among others) were manipulated to study how they might impact secondary metabolite production of the bacteria. Compounds produced by the bacteria were isolated, purified via HPLC, and analyzed using NMR and mass spectrometry. By more closely replicating the growth conditions found in the bacteria’s natural environment, and generally changing conditions known to impact metabolic activity, it may be possible to promote the production of antibiotics that are not seen under standard culture conditions.

Additionally, while T. turnerae has primarily been utilized in the natural products world, its cellulolytic properties ensure that its utility extends beyond pharmaceuticals. As such, complex cellulose-containing carbon sources were tested, ranging from paper to corn husks, to determine, broadly, whether such sources could be digested and whether known high-value compounds would still be produced by the bacteria. The investigation thus holds implications not only for natural products, but also for sustainability and second-generation biofuel production efforts.