The project is aimed at the development of new tools for the identifications of various microorganisms including bacteria causing a wide range of diseases from common cold to bloodstream infections. Knowing exactly which type of bacterium is involved in a disease is very important, since the choice of appropriate medication largely depends on it. Likewise, in case of public health or food safety, the correct classification of bacterial contaminations helps with the identification of their source and elimination of the contamination. Currently, samples containing bacterial cells are collected and sent to laboratories. Microbiologists grow the bacteria in Petri-dishes containing special nutrients. Based on the types of nutrients the bacteria can use and the results of multiple chemical tests, the bacterium is tentatively identified. If proper classification is necessary, nucleic acids are extracted from the bacterial cells, and their base-pair sequence is determined, which helps in the unambiguous identification. All of these processes are time consuming, which considerably delays the efficient intervention both in case of infectious diseases and in case of a waterborne disease outbreak. The purpose of the proposed research is to develop an alternative, much faster technique for the identification of bacteria. Mass spectrometry is an analytical technique capable of the measurement of the weight of molecules, and also the selective detection of hundreds of different molecules at the same time. We plan to use this well-established technique for looking at some special building blocks of bacterial cells. One novel aspect of the research is that mass spectrometers are not used in the traditional way, including a lengthy preparation of bacterial cells prior to analysis, but the cells are simply heated up, and electrically charged molecules formed on the boiling of cells are analysed using mass spectrometry. The idea of rapid mass spectrometric analysis by using simply heat has already been applied in case of surgery, where cancer tissue is identified in a similar way. In course of the proposed project we plan the adopt this technology (Rapid Evaporative Ionization Mass spectrometry; REIMS) for the analysis of bacteria grown in the laboratory and also for the direct analysis of liquid samples (ranging from pond water to blood) containing bacterial agents. We plan to build a large library of the spectroscopic fingerprints of the bacteria, which will be used as a training set for computer based search algorithms. The method, the database and the algorithm together will enable the unambiguous identification of bacteria in considerably shorter timeframe than the current routine. Furthermore, the proposed research can potentially lead to an approach, where bacteria are directly identified in their natural environment (e.g. in urine for a urinary infection) without growing them in the laboratory for several hours or days.