Elevated 3-hydroxypropionaldehyde production from glycerol using a Citrobacter freundii mutant

Area of Science:

• Microbiology
• Biotechnology
• Metabolic Engineering

Background:

• Glycerol is a readily available feedstock for bioproducts.
• 3-hydroxypropionaldehyde (3-HPA) is a valuable platform chemical.
• Efficient microbial production of 3-HPA from glycerol is desirable.

Purpose of the Study:

• To isolate a mutant strain of Citrobacter freundii with enhanced 3-hydroxypropionaldehyde (3-HPA) production from glycerol.
• To optimize conditions for 3-HPA production by the identified mutant.

Main Methods:

• Chemical mutagenesis of Citrobacter freundii.
• Screening using minimal medium with glycerol and phloroglucinol staining.
• Cultivation of the parent and mutant strains under varying conditions.

Main Results:

• A mutant strain, HPAO-1, was successfully isolated.
• HPAO-1 exhibited several-fold higher 3-HPA production compared to the parent strain.
• Optimal 3-HPA production by HPAO-1 occurred at specific culture volume to flask volume ratios (1:3 or 1:12.5) with 5% glycerol.

Conclusions:

• Chemical mutagenesis and a novel screening protocol effectively identified a high-yielding 3-HPA producing mutant.
• Culture volume to flask volume ratio is a critical factor influencing 3-HPA production in Citrobacter freundii.
• The isolated mutant HPAO-1 shows potential for industrial 3-HPA production from glycerol.