Glucoamylase Mutations for Low pH Stability
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Solution Overview
Problem
Current glucoamylases used for saccharification and fermentation have limitations such as low pH sensitivity, which hampers their performance in low pH environments, and there is a need for improved starch digestibility in animal feeds, particularly for ruminants.
Innovation Solution
Development of glucoamylases with specific amino acid sequences or their variants that maintain activity at low pH levels, allowing for effective saccharification and fermentation, and use as feed additives to enhance starch digestion in animals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If commercially used fungal glucoamylases are employed for saccharification and fermentation, then the process can be carried out, but the enzyme exhibits low pH sensitivity and reduced activity at low pH values below 6
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of the glucoamylase enzyme to alter its pH sensitivity characteristics. Specifically, the invention introduces mutations at positions 230 and 231 (changing glutamic acid to aspartic acid and glutamic acid to lysine, respectively) to shift the enzyme's optimal pH range and improve its activity and stability at low pH values below 6, thereby resolving the contradiction between reliability and productivity in acidic conditions.
2Productivity
If traditional glucoamylases are used for feed additives, then starch digestion can occur, but the digestibility is highly variable and insufficient for improving animal nutrition outcomes
Solution Approach 1:
The patent applies parameter changes by modifying enzymatic parameters through amino acid sequence mutations to enhance and stabilize starch digestion performance. The engineered glucoamylase with specific mutations (E230D, E231K) demonstrates improved and more consistent starch digestibility in animal feeds, providing reliable nutritional outcomes rather than highly variable performance.
3Object-affected harmful factors
If fermentation is carried out at low pH to minimize contamination risk, then the safety is improved, but the enzyme performance and glucose yield are reduced
Solution Approach 1:
The patent applies parameter changes by engineering the glucoamylase to function optimally at low pH values (pH 3.0-5.0), thereby maintaining the safety benefits of low pH fermentation while eliminating the penalty of reduced enzyme performance. The mutated enzyme retains high activity in the acidic environment, allowing simultaneous achievement of low contamination risk and high glucose yield.
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 glucoamylases with enhanced low pH stability and activity improve the efficiency of saccharification and fermentation processes, and increase starch digestibility in animal feeds, leading to higher glucose yields and better nutritional outcomes.
Implementation Method 1
Glucoamylase (1,4-alpha-D-glucan glucohydrolase, EC 3.2.1.3) is an enzyme, which catalyzes the release of D-glucose from the non-reducing ends of starch or related oligo- and poly-saccharide molecules
Implementation Method 2
Glucoamylases that are active at a low pH in the presence of pepsin can be useful as a feed additive for ruminants
Data Source
AI summary
Described are methods for saccharifying starch-containing materials using a glucoamylase, methods for producing fermentation products, and fermentation products produced by the method thereof as well as methods for increasing starch digestibility in a ruminant using at least one of the glucoamylases described herein.