Physiological studies of Bacillus subtilis minicells

Area of Science:

• Microbiology
• Cell Biology
• Biochemistry

Background:

• Minicells are anucleate cell fragments produced by certain bacterial strains.
• Studying minicells offers insights into cellular processes without the confounding factor of a nucleus.

Purpose of the Study:

• To purify and characterize Bacillus subtilis minicells for physiological studies.
• To assess the metabolic activity and integrity of purified minicells.

Main Methods:

• Ultrasound treatment to lyse parental cells while preserving minicells.
• Autolysis assays under various conditions (medium, temperature, genotype).
• Lysozyme treatment for miniprotoplast formation.
• Luciferase assay for ATP level measurement.
• Respirometry for oxygen consumption analysis.

Main Results:

• High-purity minicell preparations (>10^9 minicells/ml) with minimal parental cell contamination (<10^4 CFU/ml).
• Purified minicells show resistance to autolysis compared to parental cells, with rates influenced by production medium, incubation temperature, and genotype.
• Minicells possess functional energy metabolism, evidenced by ATP production and oxygen consumption.
• Minicells can be converted to miniprotoplasts upon lysozyme treatment.

Conclusions:

• Ultrasound-purified Bacillus subtilis minicells are stable and metabolically active.
• These anucleate cell models are suitable for investigating fundamental physiological processes.
• Minicell autolysis is influenced by environmental and genetic factors, offering avenues for further research.