Quantification of corrinoids in methanogenic bacteria

Area of Science:

• Microbiology
• Biochemistry

Background:

• Corrinoids, including vitamin B12, are vital cofactors for numerous enzymes.
• Methanogens are a diverse group of archaea crucial for carbon cycling.
• Understanding corrinoid biosynthesis and levels in methanogens is important for microbial metabolism studies.

Purpose of the Study:

• To quantify corrinoid levels in various methanogen species.
• To investigate the influence of growth conditions on corrinoid content.
• To compare corrinoid concentrations across different methanogen genera.

Main Methods:

• Bioassay using the corrinoid auxotroph Escherichia coli 113-3.
• Cultivation of methanogens on different carbon and energy sources (H2/CO2, methanol).
• Quantification of corrinoids via dry cell weight measurements.

Main Results:

• All five examined methanogen species contained over 0.65 nmol corrinoid/mg dry cells when grown on H2/CO2.
• Methanosarcina barkeri grown on methanol showed the highest corrinoid levels, reaching 4.1 nmol/mg cells.
• Corrinoid amounts in Methanosarcina barkeri varied with growth conditions and were consistently higher than in studied Methanobacterium species.

Conclusions:

• Methanogens possess substantial intracellular corrinoid concentrations.
• Methanosarcina barkeri demonstrates particularly high corrinoid accumulation, influenced by growth substrates.
• Corrinoid levels in methanogens are species- and condition-dependent, highlighting metabolic diversity.