METHEMOGLOBIN FORMATION BY STERILE CULTURE FILTRATES OF PNEUMOCOCCUS.

Area of Science:

• Microbiology
• Biochemistry

Background:

• Pneumococcus produces hydrogen peroxide during aerobic culture.
• Hydrogen peroxide can oxidize oxyhemoglobin to methemoglobin.
• Blood catalase typically neutralizes hydrogen peroxide, preventing hemoglobin oxidation.

Purpose of the Study:

• To investigate the mechanism by which sterile pneumococcus filtrates convert oxyhemoglobin to methemoglobin.
• To determine the role of hydrogen peroxide and bacterial cell constituents in this conversion.
• To elucidate the conditions under which pneumococcus can induce methemoglobin formation independently of blood catalase.

Main Methods:

• Culturing Streptococcus pneumoniae (pneumococcus) aerobically.
• Preparing sterile filtrates from pneumococcus cultures.
• Analyzing the effect of these filtrates on crystalline oxyhemoglobin solutions.
• Investigating the influence of hydrogen peroxide and bacterial cell components on methemoglobin formation.
• Comparing reactions in the presence and absence of blood catalase.

Main Results:

• Sterile pneumococcus filtrates containing hydrogen peroxide converted oxyhemoglobin to methemoglobin in catalase-free solutions.
• This conversion was dependent on hydrogen peroxide and the absence of blood catalase.
• In catalase-containing hemoglobin solutions, a labile intracellular pneumococcal substance was involved.
• This substance was susceptible to oxidation, and its activity depended on liberation and protection from oxidants in the culture medium.

Conclusions:

• Pneumococcus can generate methemoglobin-forming activity through hydrogen peroxide and labile intracellular factors.
• Optimal conditions involve the release of these factors and their protection from oxidative degradation.
• This mechanism allows pneumococcus to convert oxyhemoglobin to methemoglobin even in the presence of blood catalase, under specific cultural conditions.