Purification and properties of Streptococcal competence factor isolated from chemically defined medium

Area of Science:

• Microbiology
• Biochemistry

Background:

• Group H streptococci produce a competence factor essential for genetic transformation.
• Efficient isolation and characterization of this factor are crucial for understanding bacterial conjugation.

Purpose of the Study:

• To develop a procedure for isolating and purifying the competence factor from group H streptococci, strain Challis-6.
• To perform partial characterization and chemical analysis of the purified competence factor.

Main Methods:

• Isolation and purification using a defined medium.
• Homogeneity assessment via electrofocusing and SDS-PAGE.
• Chemical analysis to determine composition and properties.

Main Results:

• A high-purity competence factor was successfully isolated.
• The factor is a small, dialyzable, highly basic compound.
• It is colorless, thermoresistant, and free from lipids, phosphorus, and carbohydrates.

Conclusions:

• Competence factor's biological activity is trypsin-sensitive but resistant to other enzymes (DNase, RNase, lipase, lysozyme).
• A high isoelectric point (above pH 11.0) suggests it may be a protamine or a polymer of basic amino acids.
• The potential involvement of a polyamine in the polypeptide structure was not ruled out.