Optimization of the first extraction protocol for metabolomic studies of Brucella abortus.

Brucellosis is a zoonosis prevalent worldwide and very recurrent in less developed or developing regions. This zoonosis affects livestock, generating high financial losses to producers, in addition to transmitting diseases to humans through meat consumption or handling contaminated products and animals. In this study, five extraction methods for Brucella abortus intracellular metabolites, using different solvent compositions and cell membrane disruption procedures, were evaluated. Derivatized extracts were analyzed by GC-HRMS. Raw data were processed in XCMS Online and the results were evaluated through multivariate statistical analysis using the MetaboAnalyst platform. The identification of the extracted metabolites was performed by the Unknowns software using the NIST 17.L library. The extraction performance of each method was evaluated for thirteen representative metabolites, comprising four different chemical classes. Most of these compounds are reported in the cell membrane composition of Gram-negative bacteria. The method based on extraction with methanol/chloroform/water presented the best performance in the evaluation of the extracted compounds and in the statistical results. Therefore, this method was selected for extracting intracellular metabolites from cultures of Brucella abortus for untargeted metabolomics analysis.