Thermophilic PHB Depolymerase Mutations for Industrial Stability
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Solution Overview
Problem
Existing PHA depolymerases are not conducive to industrial processes due to insufficient thermodynamic and thermal stability, kinetic speed, and environmental adaptability, particularly in the presence of contaminants like feces and urine, necessitating improved catalysts for biopolymer degradation and decontamination.
Innovation Solution
Development of modified thermophilic PHB depolymerases with single-site mutations for enhanced stability and activity at high temperatures, combined with bioreactor systems for simultaneous degradation and decontamination of biopolymers in post-consumer products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If natural PHA depolymerases are used for industrial processing, then the process can be simple and cost-effective, but the enzymes lack thermodynamic and thermal stability, resulting in short operational lifespan
Solution Approach 1:
The patent applies parameter changes by modifying specific amino acid residues in the enzyme sequence (e.g., changing residues at positions 3, 10, 15, 33, 41, 44, 49, 50, 62, 67, 78, 91, 92, 93, 97, 100, 102, 114, 122, 123, 124, 125, 127, 128, 129, 135, 139, 144, 145, 148, 152, 157, 159, 160, 167, 169, 184, 189, 200, 202, 206, 209, 233, 259, 260, 261, 269, or 275) to enhance thermal and thermodynamic stability while maintaining catalytic activity
Solution Approach 2:
The patent creates a composite enzyme system by combining modified PHA depolymerase with industrial processing conditions (high temperature, controlled pH, presence of contaminants), effectively creating an engineered biocatalyst that integrates multiple functional requirements
2Productivity
If natural PHA depolymerases are used, then the process can operate under mild conditions, but the kinetic speed is insufficient for industrial-scale production
Solution Approach 1:
The patent modifies enzyme parameters including amino acid sequence, active site residues, and structural conformations to increase catalytic rate and substrate turnover, enabling faster degradation of PHA polymers while maintaining consistent activity across industrial batches
3Adaptability or versatility
If the enzyme must function in contaminated industrial environments, then the process can handle real-world waste streams, but the enzyme activity is inhibited by contaminants like feces and urine
Solution Approach 1:
The patent converts the harmful effect of contaminants into a selective pressure that drives evolution of enzyme resistance. By exposing the enzyme to contaminated environments during evolution or using contaminants as selective agents, the patent develops enzymes that not only tolerate but can function effectively in the presence of feces, urine, and other industrial waste contaminants
Solution Approach 2:
The patent modifies enzyme parameters including surface charge distribution, hydrophobicity, and structural rigidity to reduce binding affinity with contaminants while maintaining catalytic activity, enabling the enzyme to function reliably in contaminated industrial environments
4Productivity
If high temperature processing is used to improve degradation speed, then productivity increases, but enzyme stability decreases due to thermal denaturation
Solution Approach 1:
The patent changes the thermal parameters of the enzyme by introducing stabilizing mutations that increase the melting temperature and reduce denaturation rates, allowing the enzyme to maintain structural integrity and catalytic activity at elevated temperatures suitable for industrial processing
Solution Approach 2:
The patent creates a thermally stable enzyme-composite system that integrates heat-resistant structural features with catalytic functional regions, enabling simultaneous operation at high temperatures that provide both rapid degradation and maintained enzyme stability
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 modified PHB depolymerases exhibit improved stability and kinetic characteristics, enabling efficient degradation and decontamination of biopolymers in high-temperature industrial processes, even in contaminated environments.
Implementation Method 1
PHA depolymerases are enzymes that catalyze the degradation of polyhydroxyalkanoate biopolymers
Implementation Method 2
a PHA depolymerase (PHADase)... an enzyme that is used for any bio-industrial process
Implementation Method 3
an enzyme for use in an industrial process should be thermodynamically and/or thermally stable in order to be long-lived in the process
Implementation Method 4
improved stability and kinetic characteristics, enabling efficient degradation and decontamination of biopolymers in high-temperature industrial processes
Data Source
AI summary
The present invention relates to a method for treatment of polyhydroxyalkanoate (PHA) containing post-consumer product, the method comprising contacting a post-consumer product with a polypeptide that can catalyze degradation of the PHA, the contact taking place at a temperature at least 45° C. In a specific embodiment, the poly peptide is a wild-type PHA depolymerase expressed by a thermophilic microorganism or a modified PHA depolymerase that includes one or more single-site mutations as compared to the wild-type PHA depolymerase. In another specific embodiment, the polypeptide comprising a modified poly hydroxy butyrate (PHB) depolymerase comprising one or more single-site mutations as compared to SEQ ID NO: 1, and the modified PHB depolymerase having an optimum temperature of at least 45° C. The present invention also relates to a host cell transformed to express a polypeptide that catalyzes degradation of a PHA, the polypeptide having an optimum temperature for the degradation reaction of at least 45° C., wherein the host cell is selected from an E. coli cell or a thermophilic microorganism.