Astaxanthin High-Titer Yeast Chassis and Enzyme Evolution Service

Astaxanthin is a potent natural carotenoid with high value in aquaculture (pigmentation) and cosmetics (antioxidant). Traditional production via Haematococcus pluvialis suffers from a long culture cycle and susceptibility to contamination. While yeast expression offers scalability, the product often exhibits low stability and susceptibility to degradation within the host system, leading to low final yield.

CD Biosynsis resolves these bottlenecks by combining metabolic engineering and enzyme optimization. We focus on modification of the beta-carotene pathway in Saccharomyces cerevisiae to maximize the precursor flux towards carotenoid synthesis. Crucially, we use directed evolution of the key enzymes crtW and crtZ to enhance their specific activity and thermal stability. Our goal is to deliver a robust, high-yielding yeast strain capable of efficiently producing stable, high-purity Astaxanthin at commercial scale.

Pain Points

Industrial microbial production of Astaxanthin is limited by the following challenges:

• Rate-Limiting Precursor Supply: The native yeast pathway limits the precursor Geranylgeranyl Diphosphate ( GGPP ) , thereby constricting the entire beta-carotene pathway and subsequent Astaxanthin yield.
• Inefficient Terminal Enzymes: The key enzymes, beta-carotene ketolase ( crtW ) and beta-carotene hydroxylase ( crtZ ) , are responsible for the final two conversion steps. Their low specific activity and poor stability in the yeast environment lead to the accumulation of intermediates and low final Astaxanthin purity .
• Product Degradation and Storage: Astaxanthin is highly prone to oxidation and enzymatic degradation within the microbial host, resulting in significant product loss during fermentation and purification.
• Pathway Imbalance: The lack of coordination between precursor synthesis and the carotenoid pathway causes a metabolic imbalance , leading to inconsistent yields and poor flux control.

The solution requires a synchronized metabolic pathway and super-active, stable terminal enzymes.

Solutions

CD Biosynsis applies advanced enzyme and metabolic engineering to achieve high flux and superior product stability in Astaxanthin production:

Modification of the beta-carotene Pathway

           

We engineer the upstream GGPP and beta-carotene biosynthesis genes (e.g., tHMG-CoA Reductase, crtE , crtB , crtI ) to create a high-flux carotenoid backbone , ensuring maximal carbon flow into the pathway.

Directed Evolution of crtW and crtZ Enzymes

We apply directed evolution to crtW and crtZ to increase their specific activity, substrate affinity, and thermal/oxidative stability, ensuring rapid and complete conversion of beta-carotene to Astaxanthin.

Stable Intracellular Storage Engineering

The yeast host is engineered to enhance lipid body formation and/or modify cell membrane components, promoting the stable and protective accumulation of Astaxanthin against degradation and oxidation within the cell.

Redox Balance and Oxygen Supply Optimization

We modify the host's redox systems ( NADPH/NADP+ ) to meet the high demand of the hydroxylase crtZ . Fermentation protocols are co-optimized to ensure the necessary oxygen supply for efficient crtW and crtZ activity.

This approach transforms the yeast chassis into a highly efficient cellular factory for Astaxanthin production, overcoming the limitations of both algae and conventional yeast systems.

Advantages

Choosing CD Biosynsis's Astaxanthin engineering service offers the following core value:

Rapid and Scalable Fermentation Cycle

Yeast production drastically reduces the culture cycle time compared to slow-growing microalgae, enabling continuous, high-volume industrial production.

High Product Stability and Purity

Enhanced intracellular storage mechanisms and efficient terminal enzymes minimize degradation and accumulation of intermediates, ensuring high final product purity .

Super-Active Engineered Enzymes

Directed evolution delivers crtW and crtZ variants with superior specific activity , maximizing the metabolic flux and final Astaxanthin titer.

Reduced Extraction Cost

Yeast biomass offers simpler and more cost-effective extraction and purification than fragile microalgae, lowering overall manufacturing costs.

Robust and Predictable Chassis

The engineered S. cerevisiae chassis is genetically stable and robust for large-scale fed-batch fermentation under controlled, predictable conditions.

We are committed to delivering the highest-performing microbial strains to meet the global demand for high-quality Astaxanthin.

Process

CD Biosynsis's Astaxanthin strain engineering service follows a standardized research workflow, ensuring every step is precise and controllable:

• Target Definition and Pathway Analysis: Define the target Astaxanthin titer ( g/L ) and purity. Conduct a Metabolic Control Analysis ( MCA ) on the GGPP and beta-carotene pathways to identify precise bottlenecks.
• Enzyme Engineering ( crtW/crtZ ) and Screening: Use directed evolution with high-throughput screening to select crtW and crtZ variants exhibiting the highest specific activity and thermal stability.
• Pathway Integration and Chassis Modification: Integrate the optimized MEV/beta-carotene pathway and the engineered crtW/crtZ genes into the S. cerevisiae chromosome for stable and high-level expression .
• Product Storage and Stability Optimization: Engineer genetic targets related to lipid body formation or membrane composition to enhance the intracellular stability and protective accumulation of Astaxanthin.
• Performance Validation Experiments: Conduct comparative fed-batch fermentation, measuring the final Astaxanthin titer, total carotenoid yield, and specific productivity using HPLC .
• Result Report Output: Compile a Strain Engineering Experimental Report that includes genetic maps, metabolic flux data, enzyme stability reports, and a final titer/yield certificate, supporting commercial documentation.

Technical communication is maintained throughout the process, focusing on timely feedback regarding yield improvement and stability enhancement.

Achieve industrial-scale, stable Astaxanthin production! CD Biosynsis provides customized strain engineering solutions:

• Detailed Metabolic Flux and Enzyme Kinetic Report , highlighting the specific contribution of each engineered element.
• Contracted clients receive consultation on optimizing the fermentation oxygen supply and feeding strategy for maximal carotenoid accumulation.
• Experimental reports include complete raw data on titer, purity, and strain stability , essential for regulatory approval and market entry.