Effect of peptone on Azotobacter morphology

Area of Science:

• Microbiology
• Bacterial Physiology
• Cell Morphology

Background:

• Azotobacter vinelandii exhibits pleomorphism, a change in cell shape and size.
• Growth medium components can influence bacterial morphology and physiology.

Purpose of the Study:

• To investigate the cause of pleomorphism in Azotobacter vinelandii cultures.
• To identify the specific component in Difco peptone responsible for inducing morphological changes.

Main Methods:

• Culturing Azotobacter vinelandii with varying concentrations of Difco peptone.
• Observing morphological changes and assessing osmotic fragility of bacterial cells.
• Identifying the pleomorphism-inducing agent within the peptone.

Main Results:

• Addition of Difco peptone induced pleomorphism, characterized by transient "fungoid cells".
• These fungoid cells were osmotically fragile but became stable after approximately 48 hours.
• Glycine was identified as the specific component in peptone responsible for inducing pleomorphism.

Conclusions:

• Glycine is a key factor inducing pleomorphism in Azotobacter vinelandii.
• The induced pleomorphic forms exhibit transient osmotic instability.