Metabolomic and Lipidomic Profiling of Bacillus Using Two-Dimensional Tandem Mass Spectrometry

Lipidomic and metabolomic profiles of sporulated and vegetative Bacillus subtilis and Bacillus thuringiensis from irradiated lysates were recorded using a quadrupole ion trap mass spectrometer modified to perform two-dimensional tandem mass spectrometry (2D MS/MS). The 2D MS/MS data domains, acquired using a 1.2 s scan of negative ions generated by nanoelectrospray ionization of microwave irradiated spores, showed the presence of dipicolinic acid (DPA) as well as various lipids. Aside from microwave radiation to extract DPA and lipids from spores, sample preparation was minimal. Characteristic lipid and metabolic profiles were observed using 107─108 cells of the two Bacillus species. Major features of the lipid profiles observed for the vegetative states included sets of phosphatidylglycerol (PG) lipids. Product ion spectra were extracted from the 2D MS/MS data, and they provided structural information on the fatty acid components of the PG lipids. The study demonstrates the flexibility, speed, and informative power of metabolomic and lipidomic fingerprinting for identifying the presence of spore-forming biological agents using 2D MS/MS as a rapid profiling screening method.