(300f) Noninvasive Measurement of Yeast Cell Interactions Using Laser Tweezers Optical Trapping

Interactions between cells are of great importance for many reasons including biofilm formation, transmission of infectious diseases and biofuel production. Optical tweezers have proven to be a powerful tool for the noninvasive measurement of electrostatic interaction forces between colloidal particles, and a great body of literature exists for interactions of various particles quantified through several analysis methods. Yeast cells serve as a living corollary to spherical colloids, given their relative shape and size and ability to maintain a surface charge. In addition, yeast flocculation is a hugely important and well studied phenomenon that has obvious impact for beer production. In this study, optical tweezers are used to trap two living yeast cells, bring them into contact, and observe the force required to separate the cells all the while simultaneously monitoring the interaction force between the cells. Using the direct force measurement technique, attractive forces of ~500 femtoNewtons were measured between two approaching cells. Eventually the cells touched and stuck to one another. The force required to separate the two cells was also measured.

Acknowledgements:

This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.