Determination of biofilm mechanical properties from tensile tests performed using a micro-cantilever method

Recently, a micro-cantilever method was introduced for measuring the ultimate tensile strength of intact bacterial biofilms. Herein, is reported the analysis of the video files from the testing of a 4-day-old Staphylococcus epidermidis biofilm to determine the elastic modulus, toughness, and failure strain. Elastic modulus (1270 +/- 280 Pa) was within the range of previously reported values (17-6000 Pa). The high failure strains (240 +/- 16%) indicate the substantial ductility of bacterial biofilms. In addition, the toughness of the biofilm sample was determined from the area under the stress-strain plot (2.8 +/- 0.44 kJ m(-3)). Thus, it was demonstrated that the micro-cantilever test video files can be used for the determination of other mechanical property parameters besides ultimate tensile strength.