Influence of cobalt on fermentative methylation

Area of Science:

• Microbiology
• Natural Product Chemistry
• Fermentation Technology

Background:

• Streptomyces rishiriensis is known to produce multiple antibiotics.
• Strain selection focused on isolating the most active component, coumermycin A.
• Understanding the composition of coumermycin A is crucial for optimizing its production.

Purpose of the Study:

• To elucidate the chemical structure of coumermycin A.
• To investigate methods for selectively producing a specific coumermycin A fraction.
• To identify factors influencing coumermycin A biosynthesis.

Main Methods:

• Strain selection and culture optimization for coumermycin A production.
• Chemical hydrolysis of coumermycin A using barium hydroxide.
• Separation and identification of hydrolysis products via paper chromatography.
• Fermentation studies with varying metal ion concentrations in the medium.

Main Results:

• Coumermycin A was resolved into two distinct fractions, coumermycin A(1) and coumermycin A(2), based on their pyrrole carboxylic acid moieties.
• Hydrolysis yielded 5-methyl-pyrrole-2-carboxylic acid and pyrrole-2-carboxylic acid.
• Addition of cobalt ions (0.01 mug/ml) to the fermentation medium exclusively directed production towards coumermycin A(1).
• Nickel ions showed no significant effect, likely due to cobalt contamination.

Conclusions:

• Coumermycin A is a complex of at least two related compounds.
• Cobalt is a key element for the selective biosynthesis of coumermycin A(1).
• This finding allows for targeted production of the more active coumermycin A(1) fraction.