Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2013

Extracellular prokaryotic vesicles as drug delivery systems for bioactive compounds? (#284)

Rouba Ballouk 1 , Elliot Best 1 , Tanya Pereira 1 , Gary Dennis 1 , Jo-Anne Chuck 1
  1. University of Western Sydney, Parramatta, NSW, Australia

Prokaryotes often disseminate hydrophobic compounds such as quorum sensing molecules and antibiotics into aqueous environment.   Some of these compounds are found at concentrations higher than their solubility suggesting that they are packaged by the organism for secretion.  One example is Streptomyces nodosus which can produce the antifungal Amphotericin B at 4 g/L whereas its solubility in water is approximately 1 µg/mL.  Using alginate encapsulated amphotericin B and S. nodosus condition medium we have demonstrated that the increase in solubility is not due to chemical association with media components.  The report of aqueous droplets containing high concentrations of vesicles formed on the hydrophobic surface of Streptomyces colonies suggest this maybe a trafficking mechanism for such compounds.  As methods to generate droplets on the colonies of S. nodosus are not available, LC-MS and GC-MS screening of the droplets found on the colonies of 35 Streptomyces soil isolates has been undertaken. Analysis for structural lipids and vesicle components revealed that hopanoids, found in Frankia sp. vesicles were not present indicating that they are not ubiquitous in bacterial vesicles.