Chitosan enhances gas vesicle flotation

Addition of even small quantities of chitosan led to a notable increase in the hydrodynamic radius of the gas vesicles and a significant effect on the rate of decrease of optical density. To verify that the gas vesicles were actually floating, images of gas vesicle suspensions were taken at regular intervals over two hours.

While native gas vesicles retained an almost uniform distribution throughout the column, the suspension containing chitosan treated gas vesicles quickly cleared up. The images that follow were taken at ten minute time intervals for two hours.

Native gas vesicles tend to distribute themselves uniformly throughout the column owing to strong diffusive forces Gas vesicles treated with chitosan cleared up to the top of the column within a few minutes

Evidently, flocculation of gas vesicles using chitosan is a rapid, effective method to aggregate gas vesicles, increase their hydrodynamic radius, and cause them to float.