12/16/2023 0 Comments Tryptic soy broth media![]() coli strain grown on both minimal (M9) and rich media. Two-dimensional electrophoresis has been used to visualize the protein expression differences for an E. Thus, the question remains how applicable will this technology be with automated identification for organisms grown under conditions different from the signature conditions? In particular, can the bacterial signatures generated by MALDI-TOF MS on clean samples cultured in rich media in the laboratory be used to identify the same organisms cultured under different growth conditions, such as minimal media or blood agar plates? The effect of various culture media on MALDI-TOF MS identification is examined with the media selection based on previous reports of inducing physiological changes in the organisms of interest.Īccording to previous reports, use of the minimal medium chosen for this study has induced changes in protein expression and cell envelope composition for both E. ( 2) recently showed that growth on two different media (Mueller-Hinton agar and Columbia blood agar) did not significantly alter the MALDI-TOF MS profiles. ( 1) also showed visible differences in the MALDI-TOF MS profiles for Escherichia coli obtained throughout the growth curve. ( 16) indicated that different nutrients might affect the pattern of protease production in bacteria. Questions have arisen as to whether microorganisms can be identified by this method if they are grown under different culturing conditions which may turn on different proteins. Also established was an automated statistically based algorithm for objective analysis and evaluation of the MALDI-TOF MS data. ![]() ![]() The ability of MALDI-TOF MS to identify bacteria to the species level in pure cultures and simple microbial mixtures under carefully controlled culture and analysis conditions has been established already ( 20). The approach chosen at Pacific Northwest National Laboratory (PNNL) was to develop a library of reproducible spectral signature peaks characteristic of different bacterial genera and species for identification of unknown samples ( 11). Bacterial identification by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) has been widely studied ( 7, 14). There is a growing need for rapid microorganism identification capabilities in cases of terrorist attacks, in food processing plants, in hospitals, and in health care facilities. ![]()
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