Cyanobacterial L-lactate Production via Light-Controlled Metabolic Pathway
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Solution Overview
Problem
Current methods for producing L-lactate are inefficient, requiring expensive substrates like glucose and relying on temperature-sensitive expression systems, which are labor-intensive and water-consuming, and have adverse effects on food supplies and energy conservation.
Innovation Solution
A scalable process using cyanobacterial cells capable of converting CO2 into L-lactate with light as the sole energy source, employing a regulatory system responsive to light intensity or nutrient concentration to control enzyme expression, optimizing the conversion of Calvin cycle intermediates into L-lactate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional microbial fermentation using lactic acid bacteria is used to produce L-lactate, then L-lactate production is achieved, but expensive substrates like glucose are required and high energy initial compounds are consumed
Solution Approach 1:
The patent changes the fundamental parameter of carbon source from organic substrates (glucose) to inorganic CO2, and energy source from chemical to solar light. This is achieved by introducing heterologous genes (ldh, pck, gapA) into cyanobacteria to create a metabolic pathway that converts CO2 through Calvin cycle intermediates to L-lactate, driven by photosynthetic energy
Solution Approach 2:
The patent replaces the biological fermentation system (lactic acid bacteria) with a photosynthetic system (cyanobacteria). This substitution allows the use of solar energy and CO2 instead of requiring expensive organic substrates and external energy inputs for fermentation processes
2Adaptability or versatility
If temperature-sensitive expression systems are used in cyanobacterial production processes, then gene expression control is achieved, but the system becomes labor-intensive and requires adaptation for temperature regulation
Solution Approach 1:
The patent changes the control parameter from temperature to light intensity or nutrient concentration. The promoter regions (psbA2 for light, nifD for nitrogen) naturally respond to these environmental parameters, eliminating the need for temperature-sensitive systems and their associated operational complexities
Solution Approach 2:
The cyanobacterial system uses its native physiological responses to environmental cues (light for photosynthesis, nitrogen for growth) to automatically control gene expression. The system self-regulates production based on available resources without requiring external temperature control mechanisms
3Quantity of substance
If conventional photosynthetic processes are used to reduce CO2 to sugars and cell material, then CO2 conversion is achieved, but the overall energy conservation is highly inefficient and demands large surface areas
Solution Approach 1:
The patent extracts the L-lactate production pathway from the conventional photosynthetic pathway that ends at sugars and cell material. By introducing heterologous enzymes (ldh, pck, gapA), the system diverts metabolic flux from biomass accumulation to L-lactate production, achieving chemical production with high CO2 conversion efficiency
Solution Approach 2:
The cyanobacterial system performs multiple functions: photosynthesis for energy capture, CO2 fixation via Calvin cycle, and L-lactate production via heterologous pathways. This multi-functionality allows direct conversion of CO2 and light energy to the target chemical product, eliminating intermediate steps and improving overall efficiency
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
This process achieves efficient production of L-lactate with reduced energy consumption and water usage, utilizing CO2 as the sole carbon precursor, and allows for optimized cell density and production timing, improving yield and reducing environmental impact.
Implementation Method 1
Energy ultimately comes from the sun and this energy drives photosynthetic process in plants and photoautotrophic bacteria
Implementation Method 2
a scalable process using cyanobacterial cells capable of converting CO2 into L-lactate with light as the sole energy source
Implementation Method 3
expression of said nucleic acid molecule is under the control of a regulatory system which responds to light intensity
Implementation Method 4
regulatory system which responds to a change in the concentration of a nutrient in said culture
Implementation Method 5
the expression of said nucleic acid molecule confers on said cell the ability to convert a glycolytic intermediate such as pyruvate or glyceraldehyde 3-phosphate into L-lactate
Data Source
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AI summary
A process of producing L-lactate as defined herein by feeding carbon dioxide to a culture of a cyanobacterial cell and subjecting said culture to light, wherein said cell is capable of expressing a nucleic acid molecule, wherein the expression of said nucleic acid molecule confer on the cell the ability to convert a glycolytic intermediate into L- lactate and wherein said nucleic acid molecule is under the control of a regulatory system which responds to light or to a change in the concentration of a nutrient in said culture.