Relationship between cortex content and properties of Bacillus sphaericus spores

Area of Science:

• Microbiology
• Bacterial spore structure
• Biochemistry

Background:

• Bacillus sphaericus spores possess a complex structure crucial for survival.
• The spore cortex, primarily composed of peptidoglycan, plays a vital role in spore properties.
• Meso-diaminopimelic acid is a key component in peptidoglycan synthesis.

Purpose of the Study:

• To investigate the relationship between meso-diaminopimelic acid concentration and spore cortex content in Bacillus sphaericus mutants.
• To determine the critical cortex content required for specific spore properties.

Main Methods:

• Culturing Bacillus sphaericus mutants with varying meso-diaminopimelic acid concentrations.
• Quantifying muramic lactam content as a measure of spore cortex.
• Assessing spore properties including refractility, dipicolinic acid accumulation, and resistance to solvents.

Main Results:

• Muramic lactam content increased linearly with meso-diaminopimelic acid concentration.
• Spore cortex content could be modulated by adjusting meso-diaminopimelic acid levels.
• Refractility and dipicolinic acid accumulation required approximately 20% of maximum cortex.
• Xylene octanol resistance required approximately 25% of maximum cortex.

Conclusions:

• Meso-diaminopimelic acid concentration is a key factor in regulating Bacillus sphaericus spore cortex formation.
• Defined levels of spore cortex are essential for achieving characteristic spore properties.
• This provides a method to manipulate spore properties by controlling cortex synthesis.