Growth of the Bacillus subtilis cell surface

Area of Science:

• Microbiology
• Cell Biology
• Biochemistry

Background:

• Bacillus subtilis is a model organism for studying bacterial cell division and growth.
• The d-alanine auxotrophy in Bacillus subtilis div IV B1 dal trp highlights the essentiality of d-alanine for cell viability.

Purpose of the Study:

• To investigate the cellular consequences of d-alanine deprivation in a Bacillus subtilis double mutant.
• To understand the role of d-alanine in maintaining cell shape and preventing lysis.

Main Methods:

• Construction of a Bacillus subtilis double mutant (div IV B1 dal trp) requiring d-alanine.
• Culturing the mutant strain under d-alanine replete and deprived conditions.
• Microscopic observation of cellular morphology and ultrastructure.

Main Results:

• The double mutant exhibited filamentous and minicell morphology.
• Deprivation of d-alanine induced cell bulging and subsequent lysis.
• Minimal ultrastructural changes were observed in the cell envelope during bulge formation.

Conclusions:

• d-alanine is essential for normal cell growth and division in Bacillus subtilis.
• The absence of d-alanine leads to specific morphological defects and cell death.
• Cell envelope integrity is compromised upon d-alanine withdrawal, preceding visible lysis.