Cellulolytic Ethanologenic Bacteria for Direct Cellulose-to-Ethanol Conversion
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Solution Overview
Problem
The production of bioethanol from cellulose is hindered by the crystalline structure of cellulose, which makes its conversion to glucose difficult and costly, and existing enzymatic and chemical hydrolysis methods are resource-intensive and costly, limiting the widespread adoption of biofuels.
Innovation Solution
A method using genetically modified ethanologenic organisms, such as Zymomonas mobilis, incorporating cellulolytic genes to degrade cellulose into glucose, which are then fermented into ethanol, minimizing the need for enzymatic cocktails and optimizing conditions for efficient conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional enzymatic hydrolysis methods are used to convert cellulose to glucose, then glucose can be produced for ethanol fermentation, but the process becomes resource-intensive and costly
Solution Approach 1:
The patent combines cellulolytic gene clusters (including endoglucanases, exoglucanases, and beta-glucosidases) into a single genetically modified organism, merging multiple enzymatic functions into one biological system that can simultaneously hydrolyze cellulose to glucose without requiring external enzymatic cocktails
Solution Approach 2:
The genetically modified organism is engineered to perform multiple functions: it possesses cellulolytic capabilities to degrade cellulose, fermentative capabilities to convert glucose to ethanol, and can operate under varying pH and temperature conditions, making it a universal solution for cellulosic ethanol production
2Quantity of substance
If chemical hydrolysis methods are used to break down cellulose, then glucose can be obtained, but the process becomes costly and requires harsh conditions
Solution Approach 1:
The patent replaces harsh chemical hydrolysis methods with a biological system that uses genetically modified organisms to perform cellulose degradation under milder, more energy-efficient conditions, substituting chemical mechanisms with biological catalysis
3Productivity
If starch-based feedstock is used for bioethanol production, then glucose can be readily extracted, but food resources are consumed and costs increase when gasoline prices decline
Solution Approach 1:
The patent changes the substrate parameter from starch to cellulose by engineering organisms with cellulolytic capabilities, enabling the system to process non-food lignocellulosic biomass while maintaining high ethanol production efficiency, thus adapting to diverse feedstock sources
4Quantity of substance
If delignification reactions are performed on lignocellulosic biomass, then cellulose can be recovered, but the process becomes complex and costly
Solution Approach 1:
The genetically modified organism performs self-service by producing its own cellulolytic enzymes to degrade cellulose, eliminating the need for external delignification and hydrolysis steps, thereby simplifying the overall process while recovering glucose for ethanol production
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 approach reduces the cost and complexity of bioethanol production by leveraging genetically modified organisms with integrated cellulolytic capabilities, enhancing the conversion of cellulose to ethanol while avoiding the limitations of enzymatic and chemical hydrolysis.
Implementation Method 1
incorporating cellulolytic genes to degrade cellulose into glucose
Implementation Method 2
which are then fermented into ethanol
Data Source
AI summary
A method of producing an alcohol or alcohol precursor from a cellulosic material and a genetically modified live ethanologenic organism, wherein the method comprises the steps of:exposing said genetically modified live ethanologenic organism to a culture media with a pH of between 2 and 9 thereby creating an incubation mixture;exposing said incubation mixture to a source of cellulose;incubating said genetically modified live ethanologenic organism in said incubation mixture with said source of cellulose under aerobic and/or anaerobic conditions at a temperature ranging from 0° C. to 60° C. for a first period of time sufficient for the degradation of cellulose, thereby creating a degraded cellulose mixture;optionally, incubating said genetically modified live ethanologenic organism in said degraded cellulose mixture under aerobic and/or anaerobic conditions at a temperature ranging from 0° C. to 60° C. for a second period of time sufficient for the production of said alcohol or alcohol precursor; andoptionally, recovering said alcohol or alcohol precursor from the cells and/or spent culture media.wherein said genetically modified live ethanologenic organism comprises at least one of the following polynucleotide sequences in its genome:i. at least one endoglucanase (cen-like) polynucleotide sequence selected from the group consisting of an endoglucanase A-like (cenA-like) polynucleotide sequence, an endoglucanase B-like (cenB-like) polynucleotide sequence and an endoglucanase C-like (cenC-like) polynucleotide sequence;ii. an exoglucanase (cex-like) polynucleotide sequence; andiii. a β-glucosidase 1 (bgl1) polynucleotide sequence;wherein said source of cellulose has a lignin content of at most 1 wt. % and a hemicellulose content of at most 15 wt. %, and wherein said live ethanologenic organism belongs to a genus is selected from the group consisting of: Aspergillus, Mucor, Zymomonas, Escherichia, Clostridia, Bacillus, and Pseudomonas.