Extracellular Pigment Synthesis Using Exported Microbial Intermediates
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Solution Overview
Problem
Existing methods for producing colourant polymers like melanin, carotenoids, and flavins are inefficient and often result in undesired byproducts, making them unsuitable for commercial use due to low yield and unwanted colour properties.
Innovation Solution
A process for extracellular production of pigment molecules by genetically engineering cells to overproduce and export specific intermediates, such as tyrosine and tyrosinase, while disrupting import genes and using signal peptides to enhance extracellular reaction and modulating the reaction with additional intermediates like cysteine and glutathione to control pigment properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If melanin is synthesized inside the cell using engineered strains, then the production process is established, but the yield per hour is low and the process is not economical for commercial use
Solution Approach 1:
The patent extracts the pigment synthesis reaction from the intracellular environment and relocates it to the extracellular medium. The engineered strain exports precursor molecules (tyrosine, cysteine) and enzymes (tyrosinase, dopachrome tautomerase) to the external environment where pigment polymerization occurs, thereby increasing production efficiency and commercial viability while avoiding intracellular metabolic constraints
2Manufacturing precision
If conventional strain engineering is used to produce pigment polymers, then production is achieved, but undesired byproducts are formed and colour properties are not controlled
Solution Approach 1:
The patent employs specific enzymes as intermediaries to control the pigment synthesis pathway. Dopachrome tautomerase acts as a key intermediary that directs the conversion of dopachrome to DHICA, thereby controlling polymerization and preventing unwanted byproducts. The extracellular environment serves as an intermediary space where substrate concentrations and enzyme activities can be optimized for precise colour control
Solution Approach 2:
The patent controls pigment properties by changing key parameters: substrate concentrations (tyrosine, cysteine, glutathione), enzyme activities (tyrosinase, dopachrome tautomerase), pH, and temperature in the extracellular medium. These parameter changes enable precise control over polymerization rate, molecular weight distribution, and final colour properties while minimizing byproduct formation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves controlled production of pigments with desired properties, such as melanin, by minimizing intracellular reactions and optimizing extracellular synthesis, leading to higher yields and improved commercial viability.
Implementation Method 1
production of the first intermediate by an engineered cell and exporting the first intermediate to an extracellular medium outside the cell
Implementation Method 2
the first intermediate reacts with the second intermediate in the extracellular medium to produce the pigment compound
Implementation Method 3
the second intermediate being active upon export to the extracellular medium, and the first and second intermediates reacting at the extracellular medium to produce the pigment compound
Implementation Method 4
In birds, various melanins contribute to feather colour. Melanin accumulation in soil is an important mode for sequestration of carbon, and melanin has been identified as a potential molecule for increasing the amount of carbon stored in soils. The black, brown, buff and Tyndall-blue pigments found in feathers, hairs, eyes, insect cuticle, fruit and seeds are usually melanins and are assumed to result from the action of tyrosinase.
Implementation Method 5
using signal peptides to enhance extracellular reaction
Implementation Method 6
modulating the reaction with additional intermediates like cysteine and glutathione to control pigment properties
Data Source
AI summary
Disclosed are processes and methods for production of pigment compounds, such as melanin, using engineered microbial systems and chemical modifications to intermediate compounds. One process involves producing a first intermediate (e.g., an amino acid like tyrosine) and a second intermediate (e.g., an enzyme like tyrosinase) within a microbial cell, exporting the intermediates to an extracellular medium, and enabling their reaction outside the cell to form the pigment compound. The microbial cell is genetically engineered to enhance production and export of intermediates, prevent reuptake, and optimize enzyme activity post-export. Additional intermediates or capping agents are introduced to modulate pigment properties, such as color, molecular weight, and solubility. The process may be applied to produce various pigments, including pheomelanin and violacein, and is scalable for industrial applications in textiles, cosmetics, and carbon sequestration. The system minimizes cellular toxicity, simplifies purification, and allows for tailored pigment production.