Mutant Aspergillus Phytases for Thermostability
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Solution Overview
Problem
Natural phytases lack sufficient thermostability and pH stability to effectively function in the high-temperature feed pelleting process and acidic environments of animal digestive tracts, limiting their bioavailability and effectiveness as animal feed supplements.
Innovation Solution
Development of mutant phytases with specific amino acid substitutions, such as A58E, P65S, Q191R, and T271R, which enhance thermostability and pH profile, maintaining activity and bioavailability in acidic environments like the gastrointestinal tract without sacrificing heat tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If natural phytases are used in feed supplements, then phosphate bioavailability is improved, but thermostability is insufficient for high-temperature feed pelleting process
Solution Approach 1:
The patent applies parameter changes by modifying amino acid residues at specific positions (58, 65, 112, 131, 149, 191, 195, and 271) in the phytase protein sequence. These molecular-level parameter changes alter the enzyme's thermal stability properties, enabling it to withstand high-temperature feed pelleting processes (70-90°C) while maintaining phosphate bioavailability function.
2Reliability
If natural phytases are used in feed supplements, then phosphate bioavailability is improved, but pH stability is insufficient for acidic environments of animal digestive tracts
Solution Approach 1:
The patent modifies the phytase enzyme's pH stability through amino acid substitutions at specific positions. These parameter changes in the protein structure enable the enzyme to maintain stability and activity in the acidic environment (pH 2.5-3.5) of animal digestive tracts, thereby improving phosphate bioavailability.
3Temperature
If amino acid substitutions are made to improve thermostability, then heat tolerance is enhanced, but enzyme activity may be compromised
Solution Approach 1:
The patent applies local quality by making targeted amino acid substitutions at specific positions (58, 65, 112, 131, 149, 191, 195, and 271) rather than throughout the entire protein. This localized modification approach enhances heat tolerance at specific structural regions while preserving the overall enzyme activity and catalytic function.
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 mutant phytases exhibit improved thermostability and pH stability, retaining activity and bioavailability in acidic environments, enhancing phosphate bioavailability in animal feed and reducing phytate-phosphorus pollution.
Implementation Method 1
Phytases catalyze the hydrolysis of phytate (myo-inositol hexakisphostate), a major storage form of phosphorus in plant seeds, to phosphate and myo-inositol
Data Source
AI summary
The present invention is directed to an isolated nucleic acid molecule encoding mutant phytases and the isolated mutant phytases themselves. The present invention further relates to methods of using the isolated nucleic acid molecules and the isolated mutant phytases of the present invention.