Resistance and germination of spores of Bacillus species lacking members of a spore integral inner membrane protein family and locations of these proteins in spores

• Published in: Journal of bacteriology p. e0021725
• Main Authors: Khan, Shermeen, Wicander, James, Korza, George, Caldbeck, Rebecca, Cowan, Ann E., Christie, Graham, Setlow, Peter
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 12.09.2025
• Subjects: Bacillus Outgrowth; Bacterial Physiology; Bacteriology; Editor’s Pick; Germination; Heat Stress; Microbial Physiology and Genetics; Research Article; Spore Cortex Degradation; Spore Germination; Spore Heat Resistance; Sporulation; Sporulation and Spore Inactivation; Sporulation Resistance Mechanisms; spore germination; spore resistance; Bacillus subtilis; spores; Bacillus megaterium; membrane fluidity
• ISSN: 0021-9193; 1098-5530; 1098-5530
• DOI: 10.1128/jb.00217-25

Spores of Bacillota are vectors for food spoilage and disease, and are hard to kill, as B. subtilis spores are killed only slowly by wet heat at 90°C. Multiple factors contribute to spores’ wet heat resistance, including low spore core water content and DNA-protective proteins. Recently, a group of spore-specific inner membrane (IM) proteins was identified as increasing IM rigidity and spore wet heat resistance. B. subtilis has five of these proteins, with multiple homologs in all Bacillus and Clostridium species. These proteins increase IM rigidity, which increases spore wet heat resistance and can either increase or decrease the rates of spore germination, with similar effects on B. megaterium spores. These proteins are thus a new factor important in spore properties.