Adipic acid tolerance screening for potential adipic acid production hosts

Area of Science:

• Biotechnology
• Microbiology
• Industrial Biotechnology

Background:

• Biobased adipic acid production is crucial for sustainable chemical manufacturing.
• Current microbial production yields are insufficient for commercialization, possibly due to adipic acid toxicity.
• Understanding microbial tolerance is key to developing efficient biobased routes.

Purpose of the Study:

• To evaluate the tolerance of various microorganisms (yeasts, fungi, bacteria) to adipic acid.
• To identify microbial candidates with high adipic acid tolerance for potential cell factories.
• To investigate the influence of adipic acid's dissociation state on microbial tolerance.

Main Methods:

• Screening of yeasts, filamentous fungi (Aspergillus niger), and bacteria for adipic acid tolerance.
• Microtitre plate and agar plate assays were conducted across a wide concentration range (0-684 mM).
• Cultivations were performed at multiple pH values to account for adipic acid's dissociation states.

Main Results:

• Yeasts and Aspergillus niger demonstrated significantly higher tolerance to adipic acid compared to bacteria.
• Microorganisms were less affected by the undissociated form of adipic acid.
• Candida viswanathii exhibited the highest tolerance, with minimal reduction in growth rate (<15%) at high concentrations, independent of pH.

Conclusions:

• Significant differences in adipic acid tolerance exist among yeasts, fungi, and bacteria, likely due to physiological and metabolic variations.
• Candida viswanathii is a promising candidate for a microbial cell factory for biobased adipic acid production.
• Further research into the physiological basis of tolerance could optimize biobased adipic acid synthesis.