High-throughput mass measurement of single bacterial cells by silicon nitride membrane resonators

We present a technological approach to precisely measure the dry mass of many individual cells of a bacteria colony. In this technique, bacteria are transported from aqueous solution into gas phase and subsequently guided to the surface of a silicon nitride membrane resonator. Abrupt downshifts in the membrane eigenfrequencies are measured upon every bacterium adhesion and are related to the dry mass of the cell by theoretical methods. We measure the dry mass of Escherichia coli K-12 and Staphylococcus epidermidis with an unprecedented throughput of 20 cells/min and with a mass resolution of.1%. Finally, we apply the Koch & Schaechter model to assess the intrinsic sources of growth stochasticity.