Electroactivity of weak electricigen Bacillus subtilis biofilms in solution containing deep eutectic solvent...

Area of Science:

• Microbiology
• Biotechnology
• Electrochemistry

Background:

• Bacillus subtilis is a versatile bacterium used as a cell factory for microbial production.
• Electroactivity, linked to metabolic activity, can enhance bioproduction in B. subtilis.
• Deep eutectic solvents (DESs) offer potential as biocompatible additives.

Purpose of the Study:

• To investigate the use of DESs and their components for enhancing B. subtilis electroactivity.
• To evaluate the impact of DESs on microbial growth and biofilm formation.
• To explore the potential of DESs in electrofermentative bioproduction.

Main Methods:

• Cultivation of Bacillus subtilis in the presence of various DESs and components.
• Assessment of electroactivity using differential pulse voltammetry.
• Analysis of growth kinetics and biofilm formation.
• High-performance liquid chromatography to study metabolic pathways.

Main Results:

• An aqueous choline chloride: glycerol (1:2 mol mol-1) mixture showed the strongest electroactivity enhancement.
• Low concentrations (50-500 mM) of this mixture promoted pseudo-diauxic growth and increased biofilm formation.
• Similarities were observed between DES-induced electroactivity enhancement and B. subtilis quinone redox metabolism.
• Choline chloride-based DESs improved biomass and productivity in biofilm-based electrofermentation.

Conclusions:

• Choline chloride-based aqueous eutectic mixtures are effective in enhancing Bacillus subtilis electroactivity.
• These DESs can improve biomass yield and productivity in biofilm electrofermentation systems.
• The exact mechanism underlying the observed enhancements requires further investigation.