Phytosterol Bioproduction Engineering Service

Phytosterols (e.g., sitosterol, campesterol, stigmasterol) are steroid-like compounds structurally similar to cholesterol, known for their ability to lower plasma cholesterol levels. They are widely used in functional foods and pharmaceuticals. Production faces challenges: low purity in plant extraction (often mixed with fatty acids and other sterols) requiring extensive purification, and many steps in chemical synthesis (semi-synthesis from sterol precursors) resulting in high cost and waste. Biosynthesis in engineered yeast offers a sustainable, high-purity alternative.

CD Biosynsis offers a synthetic biology service focused on high-titer, high-purity Phytosterol production using Saccharomyces cerevisiae . Our core strategy involves modification of yeast sterol synthesis pathway , specifically the mevalonate (MVA) pathway, to maximize the precursor lanosterol and block the host’s native ergosterol synthesis pathway. This is coupled with the heterologous expression of phytosterol synthase —introducing key plant genes (e.g., SMT1/SMT2 for C24 methylation, and specific cyclases) necessary to convert the yeast sterol intermediates (like lanosterol) into the desired plant sterols. This integrated approach aims to deliver a high-yield, pure, and sustainable source of specific Phytosterol compounds.

Pain Points

Developing a competitive Phytosterol bioproduction route faces these key limitations:

• Low Purity in Plant Extraction: Phytosterols are obtained from vegetable oils, but are naturally present in low concentrations and mixed with sterol esters and fatty acids , complicating and increasing the cost of purification.
• Many Steps in Chemical Synthesis: Semi-synthetic production requires multiple harsh chemical reaction steps from common animal sterols, leading to high energy use, hazardous waste, and structural complexity.
• Metabolic Competition: The native yeast pathway prioritizes the synthesis of ergosterol (the host’s essential sterol) over the introduced plant sterol pathway, limiting Phytosterol yield.
• Pathway Compatibility: Converting yeast intermediates into plant sterols requires specific plant enzymes (SMT1/SMT2) that may not be optimally expressed or function efficiently in the yeast host.

A successful solution must suppress the native pathway while boosting the introduced heterologous pathway for specific product formation.

Solutions

CD Biosynsis utilizes advanced synthetic biology to engineer S. cerevisiae for high-yield Phytosterol production:

Modification of Yeast Sterol Synthesis Pathway

           

We knock out key genes (ERG5, ERG6, ERG7, ERG24) in the yeast’s native ergosterol pathway to force metabolic flux into the heterologous Phytosterol pathway.

Heterologous Expression of Phytosterol Synthase

We introduce and optimize the expression of plant Sterol C24 Methyltransferases (SMT1/SMT2) and other plant enzymes necessary to synthesize the specific Phytosterol skeleton.

Upstream MVA Pathway Enhancement

We overexpress rate-limiting enzymes (e.g., HMG-CoA reductase) in the mevalonate (MVA) pathway to dramatically increase the supply of the precursor Squalene or Lanosterol.

Cell Membrane and Lipid Optimization

We engineer the host to increase neutral lipid storage (lipid droplets) , which serve as an intracellular sink for the hydrophobic Phytosterol product, boosting accumulation and yield.

This systematic approach is focused on rebuilding the yeast’s native sterol synthesis machinery into a highly efficient Phytosterol production factory.

Advantages

Our Phytosterol engineering service is dedicated to pursuing the following production goals:

High Product Purity

Targeted metabolic pathways ensure the production of a single, specific Phytosterol (e.g., $\beta\text{-sitosterol), simplifying downstream processing.

Sustainable, Non-Plant Source

Fermentation utilizes renewable sugar feedstock , providing an alternative to extraction from vegetable oil byproducts.

Cost-Effective Bioconversion Platform

The robust yeast host facilitates high-density, large-scale fermentation at a lower cost than multi-step chemical synthesis.

High Specific Titer

Integrated pathway enhancement and sink engineering lead to significantly increased product yield per cell mass.

Customized Sterol Profile

The system allows for the precise engineering of the Phytosterol side chain to produce specific target molecules (e.g., sitosterol vs. campesterol) based on market needs.

We provide a specialized metabolic engineering platform aimed at optimizing the yield and purity of specific Phytosterol compounds.

Process

Our Phytosterol strain engineering service follows a rigorous, multi-stage research workflow:

• Native Pathway Blockade: Use CRISPR technology to knock out up to five key genes in the yeast ergosterol synthesis pathway to eliminate the native sterol product.
• Heterologous Pathway Construction: Design and integrate the plant SMT and cyclase genes (codon optimized for yeast) to initiate Phytosterol synthesis.
• Precursor Supply Enhancement: Overexpress HMG-CoA reductase and other MVA pathway genes to boost carbon flux into sterol precursors.
• Lipid Droplet Engineering: Modify genes related to lipid metabolism to maximize intracellular neutral lipid content (lipid droplets), increasing the Phytosterol storage sink.
• Fermentation Performance Validation: Test the final engineered strain in fed-batch fermentation to assess Phytosterol titer, yield, and purity (sterol profile).
• Result Report Output: Compile a detailed Experimental Report including gene modification data, sterol profiling, and fermentation metrics (yield, titer, and purity) , supporting commercial scale-up.

Technical communication is maintained throughout the process, focusing on timely feedback regarding yield and specific sterol profile.

Explore the potential for a high-purity, sustainable Phytosterol supply. CD Biosynsis provides customized strain engineering solutions:

• Detailed Metabolic Profiling Report , demonstrating the successful conversion from Ergosterol to the target Phytosterol profile.
• Consultation on post-fermentation lipid extraction methods optimized for high-efficiency Phytosterol recovery.
• Experimental reports include complete raw data on carbon yield (g Phytosterol}/\text{g sugar) and product purity , essential for food and pharmaceutical regulatory submissions.