Scalable catalyst production process for oleate hydratase whole-cell biocatalysis

Area of Science:

• Biotechnology
• Industrial Microbiology
• Biochemical Engineering

Background:

• Sustainable production of hydroxy fatty acids like 10-hydroxystearic acid (10-HSA) is crucial, offering alternatives to petrochemicals.
• Industrial biocatalysis often uses whole cells, necessitating efficient fermentation for biocatalyst production.
• Current processes require high-yielding and scalable fermentation methods to reduce costs.

Purpose of the Study:

• To establish and scale a fed-batch fermentation process for producing an Escherichia coli-based whole-cell biocatalyst.
• To optimize the process for high biomass concentration and sustained biocatalyst activity.
• To demonstrate the feasibility of the fermentation route for industrial 10-HSA production.

Main Methods:

• Developed a two-phased lactose-induced fed-batch process using Escherichia coli BL21 (DE3) expressing oleate hydratase.
• Employed an initial glucose growth phase followed by a glycerol and lactose feed phase for enzyme induction.
• Investigated the impact of different growth rates on biomass yield and biocatalyst activity.
• Scaled the process to a 150 L bioreactor to assess industrial feasibility.

Main Results:

• Achieved a high biomass concentration of 69.2 g L^-1 at an optimal growth rate, increasing yield by 80% while maintaining >85% biocatalyst activity.
• Demonstrated successful scale-up in a 150 L bioreactor, reaching 60.6 g L^-1 biomass with 91.5% conversion.
• Identified process design variables, like growth rate, as critical for high-yielding and economic biocatalyst production.

Conclusions:

• The optimized fed-batch fermentation process provides an efficient route for producing whole-cell oleate hydratase biocatalysts.
• This scalable fermentation strategy supports the industrial production of 10-HSA via biocatalysis.
• Further scale-up and integration with downstream processing are feasible for commercial 10-HSA manufacturing.