DGAT Genes Enhance Triglyceride Production in Algae
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Solution Overview
Problem
Current methods for boosting triglyceride (TAG) production in algae, such as alternating nutrient conditions or heterotrophic growth, are costly and prone to contamination, and overexpression of diacylglycerol acyltransferase (DGAT) genes in eukaryotic algae have been unsuccessful in increasing TAG production.
Innovation Solution
Introduction of novel DGAT genes from various sources, including algal, bacterial, and mammalian origins, along with localization peptides, into recombinant microorganisms to enhance TAG production, which can be targeted to specific cellular locations like chloroplasts, thereby increasing TAG synthesis efficiency and reducing production costs and contamination risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If algae are grown under nitrogen limitation to increase TAG production, then TAG concentration per cell increases, but overall lipid productivity decreases due to limited biomass accumulation
Solution Approach 1:
The patent changes the genetic parameters of the algae by introducing heterologous DGAT genes from different species (mammalian, bacterial, algal) to alter the enzymatic activity of the TAG biosynthesis pathway. This allows the system to achieve high TAG production under nutrient-replete conditions, resolving the contradiction between TAG concentration and overall productivity by decoupling these two parameters through genetic modification rather than environmental stress.
2Quantity of substance
If two-step nutrient alternating process is used to boost TAG production, then TAG yield increases, but production cost increases due to extended growth periods
Solution Approach 1:
The patent applies preliminary action by genetically engineering the algae with high-expressing DGAT genes before cultivation, so that the TAG production capability is pre-established. This allows the algae to produce high TAG yields during the growth phase itself, eliminating the need for subsequent nutrient-starvation steps and reducing the overall cultivation time while maintaining high TAG yield.
Solution Approach 2:
The patent enables continuous TAG production throughout the growth phase by introducing DGAT genes that maintain high expression levels under nutrient-replete conditions. This eliminates the intermittent production pattern of traditional two-step methods (growth phase with no TAG production followed by starvation phase with TAG production), achieving continuous useful action and reducing total cultivation time.
3Quantity of substance
If heterotrophic growth with added organic carbon is used to increase TAG production, then lipid yield increases, but contamination risk increases due to stimulation of exogenous bacteria and fungi
Solution Approach 1:
The patent uses DGAT genes as an intermediary element to achieve high lipid yield without directly adding organic carbon sources that would stimulate contaminant growth. The genetic modification acts as a mediator that enables the algae to efficiently convert available carbon into TAG through enhanced enzymatic activity, bypassing the need for heterotrophic conditions and thereby eliminating the contamination risk associated with added carbohydrates.
4Productivity
If DGAT genes are overexpressed in eukaryotic algae to increase TAG production, then TAG synthesis should increase, but previous attempts have been unsuccessful
Solution Approach 1:
The patent applies universality by testing and utilizing DGAT genes from multiple different species (mammalian, bacterial, and algal sources) to achieve TAG production in eukaryotic algae. This multi-source approach increases the likelihood of finding a compatible DGAT gene that can function effectively in the heterologous algal system, thereby improving reliability of expression and TAG production compared to attempting overexpression of a single DGAT gene.
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
The use of novel DGAT genes and localization peptides in recombinant microorganisms leads to significant increases in TAG production, with some strains producing up to 50% more lipid compared to control cells, while maintaining cost-effectiveness and minimizing contamination risks.
Implementation Method 1
In the final reaction of the Kennedy pathway, diacylglycerol (DAG), a precursor to both membrane and storage lipids, is covalently linked to a fatty acyl to produce TAG. This reaction is catalyzed by the diacylglycerol acyltransferase (DGAT) enzyme
Implementation Method 2
The invention also relates to the targeting of particular proteins to the inner membrane surface of a host-cell chloroplast
Data Source
AI summary
The present invention provides diacylglycerol acyltransferase (DGAT) genes, including genes encoding localization peptides. The present invention also provides recombinant cells, such as algae, transformed with DGAT genes and methods of using such recombinant cells to produce triglyceride.