2D vs 3D tracking in bacterial motility analysis

<abstract> <p>Digital holographic microscopy provides the ability to observe throughout a large volume without refocusing. This capability enables simultaneous observations of numbers microorganisms swimming in an essentially unconstrained fashion. However, computational tools for tracking 4D datasets remain lacking. In this paper, we examine errors introduced by bacterial motion as 2D projections vs. 3D volumes under different circumstances: bacteria free liquid media and near glass surface. We find that while XYZ speeds are generally equal or larger than XY speeds, they still within empirical uncertainties. Additionally, when studying dynamic surface behavior, Z coordinate cannot be neglected.</p> </abstract>