Enzymatic D-Mannitol Production With 2-Propanol Cofactor Regeneration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing D-mannitol suffer from inefficient sugar conversion, formation of byproducts, need for complex and expensive nitrogen sources, long fermentation times, and unsuitable cofactor regeneration systems, leading to low yields and high production costs.
Innovation Solution
An enzymatic process using NAD(P)H-dependent oxidoreductases, such as mannitol dehydrogenase, combined with alcohol dehydrogenase and 2-propanol as a cosubstrate, to regenerate cofactors, avoiding product inhibition and byproduct formation, with the use of resting cells or enzyme suspensions for substrate conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If heterofermentative lactic acid bacteria are used for fermentative D-mannitol production, then D-mannitol can be produced from D-fructose, but the conversion efficiency is low and byproducts such as lactate and acetate are formed
Solution Approach 1:
The patent extracts and uses only the essential enzymatic activity (mannitol dehydrogenase) without the complex microbial cell system. By removing the entire fermentation system and retaining only the specific enzyme needed for D-fructose conversion to D-mannitol, the process eliminates byproduct formation while maintaining high conversion efficiency.
Solution Approach 2:
The patent replaces the biological fermentation system (microorganisms, metabolic pathways, cell membranes) with a simplified enzymatic system. The mannitol dehydrogenase enzyme directly catalyzes the conversion of D-fructose to D-mannitol without requiring the complex cellular machinery and metabolic networks of heterofermentative bacteria, thereby eliminating byproduct formation.
2Quantity of substance
If heterofermentative lactic acid bacteria are used for fermentative D-mannitol production, then D-mannitol can be produced, but complex and expensive nitrogen sources are required
Solution Approach 1:
The patent removes the requirement for complex nitrogen sources by using a cell-free enzymatic system. Instead of requiring microbial cells with their associated nitrogen-containing components (yeast extract, peptone, meat extracts), the process uses purified mannitol dehydrogenase enzyme that can function without external nitrogen sources, significantly simplifying the medium composition.
3Quantity of substance
If heterofermentative lactic acid bacteria are used for fermentative D-mannitol production, then D-mannitol can be produced, but fermentation times are long
Solution Approach 1:
The patent replaces the slow microbial fermentation process with a rapid enzymatic reaction. The purified mannitol dehydrogenase enzyme catalyzes the conversion of D-fructose to D-mannitol directly and rapidly, eliminating the need for prolonged fermentation times required by heterofermentative bacteria to achieve high D-mannitol titers.
4Productivity
If cofactor regeneration systems such as glucose dehydrogenase or formate dehydrogenase are used, then NAD(P)H must be regenerated, but large amounts of water-soluble D-gluconate or CO2 are produced
Solution Approach 1:
The patent converts the harmful byproduct issue into a benefit by using 2-propanol oxidation to regenerate NAD(P)H. Instead of producing unwanted byproducts like D-gluconate or CO2, the oxidation of 2-propanol to acetone provides a clean cofactor regeneration pathway that maintains process efficiency without generating problematic substances.
Solution Approach 2:
The patent changes the substrate for cofactor regeneration from traditional options (glucose, formate) to 2-propanol. This parameter change in the regeneration system substrate leads to different reaction products (acetone instead of D-gluconate or CO2), eliminating the harmful byproduct formation while maintaining NAD(P)H regeneration capability.
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 high yields of D-mannitol with minimal byproducts, reducing production costs and time, and enabling efficient large-scale production without the need for complex separation processes.
Implementation Method 1
The reduction of D-fructose to D-mannitol is accomplished with a mannitol dehydrogenase (MDH) which requires either nicotinamide adenine dinucleotide (NAD) or nicotinamide adenine dinucleotide phosphate (NADP) as a cofactor
Implementation Method 2
the reduction of D-fructose to D-mannitol with significant product yields, the cofactor NAD(P)H required for this must be regenerated in a thermodynamically favored reaction
Implementation Method 3
2-propanol, which is oxidized to acetone
Implementation Method 4
combined with alcohol dehydrogenase and 2-propanol as a cosubstrate, to regenerate cofactors
Data Source
Figure 1
AI summary
A process for producing an aqueous solution containing D-mannitol, in which D-fructose, dissolved in an aqueous solution, is reduced to D-mannitol by an NAD(P)H-dependent oxidoreductase, forming the oxidized cofactor NAD(P)+, characterized in that the oxidized cofactor NAD(P)+ formed by the reduction is reduced to NAD(P)H by an alcohol dehydrogenase and a secondary alcohol, forming a ketone. The NAD(P)H-dependent oxidoreductase is either mannitol dehydrogenase I (EC 1.1.1.67, NADH-dependent) or mannitol dehydrogenase II (EC 1.1.1.138, NADPH-dependent).