Applied Maths NV 1 article published in JoVE Biology Use of MALDI-TOF Mass Spectrometry and a Custom Database to Characterize Bacteria Indigenous to a Unique Cave Environment (Kartchner Caverns, AZ, USA) Lin Zhang1, Katleen Vranckx2, Koen Janssens2, Todd R. Sandrin1 1School of Mathematical and Natural Sciences, Arizona State University, 2Applied Maths NV This work details procedures for rapid identification of bacteria using MALDI-TOF MS. The identification procedures include spectrum acquisition, database construction, and follow up analyses. Two identification methods, similarity coefficient-based and biomarker-based methods, are presented.