THE AUTOLYTIC SYSTEM OF PNEUMOCOCCI

Area of Science:

• Microbiology
• Enzymology
• Bacterial Cell Wall Structure

Background:

• Living Streptococcus pneumoniae cells possess a bacteriolytic system.
• This system can lyse heat-killed pneumococci, affecting Gram staining, cell morphology, and suspension clarity.

Purpose of the Study:

• To investigate the bacteriolytic system of Streptococcus pneumoniae.
• To characterize the enzyme responsible for altering Gram staining and cell lysis.
• To explore the substrate specificity of the identified enzyme.

Main Methods:

• Treatment of heat-killed pneumococci with the bacteriolytic complex.
• Partial purification and characterization of the responsible enzyme.
• Assays for enzyme activity on bacterial cell structures and specific glycosides.

Main Results:

• The bacteriolytic system causes lysis, Gram-negative conversion, and suspension clearing in heat-killed pneumococci.
• Under specific conditions, pneumococci can be rendered Gram-negative without significant morphological change or clearing.
• The enzyme responsible for Gram-negative conversion is resistant to proteolytic enzymes and retains activity on a significantly degraded cell structure.
• The same enzyme preparation liberates reducing sugars from acetyl amino glucose glucuronides.

Conclusions:

• A bacteriolytic system in living pneumococci can degrade heat-killed cells.
• A specific enzyme within this system can alter Gram staining properties and lyse pneumococci.
• This enzyme exhibits dual activity, affecting both bacterial cell walls and specific glycosidic linkages, suggesting a broader role in microbial degradation.