Citric Acid Bioproduction Engineering Service

Citric Acid is the most widely produced organic acid globally, used extensively as an acidulant, flavor enhancer, and preservative in food, as well as a chelating agent in chemical and pharmaceutical industries. Production relies almost entirely on the fermentation of Aspergillus niger . However, industrial strains often suffer from a low acid production rate in Aspergillus niger fermentation due to tight metabolic control and low yield. Furthermore, the traditional calcium citrate precipitation method leads to high extraction cost and substantial gypsum waste. This necessitates a solution that boosts both productivity and efficient product recovery.

CD Biosynsis offers a synthetic biology service focused on maximizing Citric Acid yield and simplifying downstream processing. Our core strategy involves modification of Aspergillus niger metabolic pathway , focusing on boosting flux through glycolysis and the initial stages of the TCA cycle, while knocking out enzymes that consume Citrate (e.g., isocitrate dehydrogenase) to ensure maximum accumulation. This is coupled with the optimization of cell membrane permeability by modifying membrane composition or overexpressing specific Citrate transporters. Enhanced permeability allows the Citric Acid to be efficiently secreted into the medium, leading to higher titers, reduced intracellular toxicity, and simplified downstream processing. This integrated approach aims to deliver a high-yield, pure, and economically viable Citric Acid product.

Pain Points

Maximizing the efficiency of Citric Acid bioproduction faces these key challenges:

• Low Acid Production Rate: The pathway is tightly controlled by ATP and other metabolites. Enzymes like PFK and PK are under strict feedback regulation, resulting in low carbon flux from glucose to Citrate.
• High Extraction Cost: Conventional purification requires precipitation with lime (CaOH2), resulting in low efficiency and the generation of large quantities of calcium sulfate (Gypsum) waste , increasing environmental and disposal costs.
• Metabolic Leakage: Citrate is an intermediate; it is rapidly consumed by downstream enzymes (Isocitrate dehydrogenase, Aconitase) within the TCA cycle for energy production and biomass synthesis.
• Product Toxicity: High intracellular concentration of Citric Acid is toxic to the Aspergillus host , limiting the maximum final titer achieved during fermentation.

An effective solution must boost the upstream supply, block the downstream consumption, and facilitate efficient product export.

Solutions

CD Biosynsis utilizes advanced metabolic engineering to optimize Citric Acid production in Aspergillus niger:

Modification of Aspergillus niger Metabolic Pathway

           

We overexpress key upstream enzymes (e.g., PFK) and knock out enzymes consuming Citrate (IDH) to redirect maximum carbon flux toward Citrate accumulation.

Optimization of Cell Membrane Permeability

We screen for or engineer Citrate-specific transporters/exporters to boost product secretion, relieving intracellular feedback inhibition and toxicity.

Pyruvate Carboxylase (PC) Optimization

We increase the activity or expression of PC to ensure a constant supply of Oxaloacetate (OAA) , the key co-substrate for the final Citrate synthesis step.

Morphology and Stress Tolerance Engineering

We modify the fungal morphology to favor a pellet form over a mycelial form to improve mass transfer, viscosity control, and tolerance to high Citric Acid concentrations.

This systematic approach is focused on optimizing every stage from carbon uptake to final product secretion to maximize economic efficiency.

Advantages

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

Dramatically Increased Titer

Enhanced flux and pathway blockade lead to significantly higher Citric Acid accumulation in the fermentation broth.

Reduced Downstream Processing Cost

High purity and concentration, combined with optimized secretion, simplify initial recovery , bypassing costly precipitation steps.

Minimized Byproduct Formation

Metabolic engineering reduces the co-production of isocitrate and other unwanted organic acids, simplifying purification. [Image of Cost Reduction Icon]

Low Environmental Burden

Efficient non-precipitation recovery methods and optimized fermentation reduce gypsum waste and energy consumption .

Robust Fungal Platform

A. niger is a well-established, safe (GRAS) organism with a proven track record in industrial acid production.

We provide a biosynthetic platform aimed at maximizing the yield and minimizing the purification and environmental costs of Citric Acid production.

Process

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

• Metabolic Blockade: Knock out Isocitrate Dehydrogenase (IDH) to stop Citrate from entering the downstream TCA cycle, ensuring its accumulation.
• Upstream Flux Enhancement: Overexpress PFK or Citrate Synthase to increase the rate of carbon entry into the Citrate synthesis route.
• Transporter Engineering: Introduce or upregulate Citrate-specific membrane transporters to enhance the rate of product efflux.
• Morphology and Tolerance Tuning: Modify genes related to cell wall synthesis or stress response to improve fungal morphology and tolerance to high acid concentrations.
• Fermentation Performance Validation: Test the final engineered strain in optimized submerged fermentation to assess Citric Acid titer, yield, and fermentation stability .
• Result Report Output: Compile a detailed Experimental Report including gene modification data, flux analysis, and fermentation metrics (yield, titer, and purity) , supporting process transfer.

Technical communication is maintained throughout the process, focusing on timely feedback regarding yield and product integrity.

Explore the potential for a high-performance, sustainable Citric Acid supply. CD Biosynsis provides customized strain engineering solutions:

• Detailed Metabolic Flux and Titer Analysis Report , demonstrating success in carbon redirection and titer increase.
• Consultation on downstream recovery processes optimized for high-concentration Citrate broth (e.g., membrane separation or chromatography).
• Experimental reports include complete raw data on carbon yield (g Citric Acid}/\text{g sugar) and product purity , essential for commercial application.