High-resolution solid-state 13C nuclear magnetic resonance of bacterial spores: identification of the alpha-carbon signal of dipicolinic acid

Abstract

Natural-abundance solid-state 13C nuclear magnetic resonance spectra were obtained for bacterial spores for the first time by using the technique of cross-polarization magic-angle-spinning nuclear magnetic resonance spectroscopy. A resonance at about 150 ppm, detectable in spore samples having a Mn content of less than 0.05%, was consistent with an identification as the alpha-carbon signal of calcium dipicolinate; this signal was missing from a spore sample treated with acid to release dipicolinate and from a spore coat preparation. Carbohydrate peaks were particularly intense in spores and coat preparations of Bacillus macerans. Signals ascribable to beta-hydroxybutyrate were prominent in a B. cereus sample.