Ion mobility mass spectrometry for the study of mycobacterial mycolic acids

Abstract Lipids are highly structurally diverse molecules involved in a wide variety of biological processes. The involvement of lipids is even more pronounced in mycobacteria, including the human pathogen Mycobacterium tuberculosis, which produces a highly complex and diverse set of lipids in the cell envelope. These lipids include mycolic acids, which are among the longest fatty acids in nature and can contain up to 90 carbon atoms. Mycolic acids are ubiquitously found in mycobacteria and are alpha branched and beta hydroxylated lipids. Discrete modifications, such as alpha, alpha’, epoxy, methoxy, keto, and carboxy, characterize mycolic acids at the species level. Here, we used high precision ion mobility-mass spectrometry to build a database including 206 mass-resolved collision cross sections (CCSs) of mycolic acids originating from the strict human pathogen M. tuberculosis, the opportunistic strains M. abscessus, M. marinum and M. avium, and the nonpathogenic strain M. smegmatis. Primary differences between the mycolic acid profiles could be observed between mycobacterial species. Acyl tail length and modifications were the primary structural descriptors determining CCS magnitude. As a resource for researchers, this work provides a detailed catalogue of the mass-resolved collision cross sections for mycolic acids along with a workflow to generate and analyse the dataset generated

ANTIBIOTICS SENSITIVITY TEST DIFFUSION AND DILUTION METHODS

An antibiotic sensitivity test is a method to test the response of bacteria to antibiotics. This study aims to determine the effectiveness of an antibiotic against microbial activity. The sensitivity test was conducted with two methods, namely, the diffusion method and the dilution method. The diffusion method was performed using paper discs (Kirby-Bauer) against Escherichia coli and Shigella sonnei bacteria with amoxicillin, neomycin, and sulfonamide antibiotics. The data required is the diameter of the inhibition zone. Results showed that Escherichia coli was sensitive to amoxicillin but resistant to sulfonamide and neomycin. Meanwhile, Shigella sonnei was resistant to amoxicillin, neomycin, and sulfanilamide. Furthermore, the dilution method was performed to test the potency of amoxicillin against Escherichia coli bacteria using the liquid dilution method. The data required were test tubes with liquid media that showed no turbidity. The results showed that the minimal inhibitory concentration of amoxicillin against Escherichia coli was 0.25%. Based on the results of the antibiotic sensitivity test using the diffusion and the dilution methods, it can be concluded that amoxicillin has high effectiveness against Escherichia coli bacteria with a minimum inhibitory concentration of 0.25%, while Shigella sonnei is resistant to the antibiotics tested