Oxalate-degrading Enterococcus faecalis

Area of Science:

• Microbiology
• Gastroenterology
• Biochemistry

Background:

• Oxalate degradation is crucial for preventing calcium oxalate urolithiasis.
• Oxalate-degrading bacteria are primarily known as obligate anaerobes, such as Oxalobacter formigenes.
• The isolation of oxalate-degrading facultative anaerobic bacteria from humans has not been previously reported.

Purpose of the Study:

• To isolate and characterize oxalate-degrading bacteria from human stools.
• To investigate the proteins involved in oxalate degradation in Enterococcus faecalis.
• To determine if these proteins are homologous to known oxalate-degrading enzymes.

Main Methods:

• Isolation of bacteria from human stools under anaerobic conditions.
• Culturing bacteria in a poor nutritional environment with repeated subculturing.
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to analyze protein production.
• Western blotting using antibodies against known oxalate-degrading enzymes from Oxalobacter formigenes.

Main Results:

• An oxalate-degrading Enterococcus faecalis strain was successfully isolated from human stools.
• This E. faecalis strain produced three unique proteins (65, 48, and 40 kDa) compared to non-degrading strains.
• Antibodies against oxalyl-coenzyme A decarboxylase (65 kDa) and formyl-coenzyme A transferase (48 kDa) from O. formigenes reacted with the corresponding proteins in E. faecalis.
• The oxalate-degrading ability of E. faecalis was maintained under specific nutritional and subculturing conditions.

Conclusions:

• This study reports the first isolation of oxalate-degrading facultative anaerobic bacteria (Enterococcus faecalis) from humans.
• The identified E. faecalis utilizes enzymatic pathways similar to O. formigenes for oxalate degradation, involving proteins of 65 and 48 kDa.
• These findings suggest a potential role for E. faecalis in oxalate metabolism within the human gut microbiome.