Colorimetric screening model for identification of menaquinone-7 (MK-7) producing strains

Area of Science:

• Microbiology
• Biotechnology
• Biochemistry

Background:

• Menaquinone-7 (MK-7) is a vital form of vitamin K2 with significant health implications.
• Efficient screening methods are crucial for identifying high-yield MK-7 producing microorganisms.
• Current methods for MK-7 strain identification can be indirect or labor-intensive.

Purpose of the Study:

• To develop and validate a novel, direct colorimetric screening method for MK-7 producing strains.
• To discover new microbial strains capable of producing MK-7.
• To optimize fermentation conditions for enhanced MK-7 yield.

Main Methods:

• Development of a colorimetric assay utilizing potassium permanganate for direct MK-7 strain identification.
• Screening of environmental samples, including soil from the Tibetan Plateau.
• Optimization of a fermentation medium and conditions for Bacillus subtilis GSA-184.

Main Results:

• A novel, direct colorimetric screening method for MK-7 producing strains was successfully established.
• A new MK-7 producing strain, Bacillus subtilis GSA-184, was isolated from the Tibetan Plateau.
• Optimized fermentation yielded 25.7 mg/L MK-7, with a maximum of 36.46 mg/L in a 5-L fermenter.

Conclusions:

• The developed colorimetric method is effective for identifying MK-7 producing strains.
• Bacillus subtilis GSA-184 represents a promising candidate for industrial MK-7 production.
• Optimized fermentation conditions significantly enhance MK-7 yields, paving the way for scalable production.