Implementation of a biotechnological process for vat dyeing with woad

Area of Science:

• Biotechnology
• Textile Chemistry
• Environmental Science

Background:

• Traditional woad dyeing relies on microbial reduction of indigo dye.
• Synthetic indigo and chemical agents cause environmental pollution.
• Growing demand for sustainable textile dyeing practices.

Purpose of the Study:

• Develop an environmentally friendly biotechnological process for woad vat dyeing.
• Replace polluting chemical reduction agents with microbial methods.
• Optimize fermentation conditions for efficient indigo reduction.

Main Methods:

• Comparative evaluation of yeast extract and corn steep liquor (CSL) media for Clostridium isatidis growth and reducing activity.
• Fermentation of CSL medium with woad powder under anaerobic and microaerophilic conditions in laboratory bioreactors.
• Monitoring of oxidation-reduction potential and indigo dye reduction rates.

Main Results:

• Both media supported bacterial growth and reducing activity, with CSL being effective.
• Sufficiently negative oxidation-reduction potential for indigo reduction was achieved within 24 hours in all fermentations.
• Strict anaerobiosis (N₂ flushing) resulted in significantly faster indigo dye reduction compared to microaerophilic conditions.

Conclusions:

• Corn steep liquor is a suitable medium for biotechnological woad dyeing.
• Strict anaerobic conditions enhance bacterial-driven indigo reduction.
• The developed process offers a sustainable alternative to chemical reduction agents in textile dyeing.