Effects of hydration on molecular mobility in phase-bright Bacillus subtilis spores

• Published in: Microbiology (Society for General Microbiology) 2000-01, Vol.146 (1), p.49-55
• Main Authors: Leuschner, Renata G. K, Lillford, Peter J
• Format: Article
• Language: English
• Subjects: Bacillus subtilis; Bacillus subtilis - genetics; Bacillus subtilis - physiology; Bacteriology; Biological and medical sciences; Carbon Radioisotopes - metabolism; dipicolinic acid; Freeze Drying; Fundamental and applied biological sciences. Psychology; Magnetic Resonance Spectroscopy; Microbiology; Microscopy, Electron; Microscopy, Electron, Scanning; Morphology, structure, chemical composition; Phosphorus Radioisotopes - metabolism; Picolinic Acids - metabolism; Spores, Bacterial - genetics; Spores, Bacterial - metabolism; Spores, Bacterial - physiology; Water
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/00221287-146-1-49

Unilever Research Colworth, Sharnbrook MK44 1LQ, UK 1 Author for correspondence: Renata G. K. Leuschner. Tel: [phone]. Fax: [phone]. e-mail: r.leuschner{at}csl.gov.uk The molecular mobility of 31 P and 13 C in dormant Bacillus subtilis spore samples with different water concentrations was investigated by high-resolution solid-state NMR. Lowest molecular mobility was observed in freeze-dried preparations. Rehydration to a 10% weight increase resulted in increases in molecular motions and addition of excess water furthered this effect. A spore slurry which had been freeze-dried displayed after addition of excess water similar NMR spectra to native wet preparations. Dipicolinic acid (DPA), which is mainly located in the core, was detected at all hydration levels in 13 C cross-polarization magic angle spinning (CPMAS) but not in single-pulse magic angle spinning (SPMAS) spectra, indicating that hydration had no effect on its mobility. The molecular mobility of 31 P, present mainly in core-specific components, was strongly dependent on hydration. This result suggests reversible water migration between inner spore compartments and the environment, whereas 13 C spectra of DPA indicate that it is immobilized in a water-insoluble network in the core. Scanning transmission electron microscopy revealed that freeze-dried spores were significantly longer and narrower than fully hydrated spores and had a 3% smaller volume. Keywords: Bacillus subtilis , structure, NMR, hydration, spores Abbreviations: CPMAS, cross-polarization magic angle spinning; DPA, dipicolinic acid; SPMAS, single-pulse magic angle spinning; STEM, scanning transmission electron microscopy; TEM, transmission electron microscropy a Present address: Central Science Laboratory, Sand Hutton, York YO41 1LZ, UK.