PHA Culture Viscosity Reduction via Alkaline Oxidation

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Solution Overview

Problem

Conventional methods for reducing viscosity in culture solutions containing PHA-producing microorganisms are not suitable for industrial-scale use due to high costs and inefficiencies, making it difficult to collect and purify polyhydroxyalkanoates effectively.

Innovation Solution

Adding an oxidizer, such as hydrogen peroxide, to the culture solution and adjusting the pH to a specific range (10.5 to 13.0) while maintaining a temperature between 30° C. to 75° C. to reduce viscosity and control molecular weight, facilitating easier PHA collection and purification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional viscosity reduction treatments (heat treatment, hypochlorite addition, nuclease addition) are used, then nucleic acid degradation is achieved, but production costs increase and industrial scalability is reduced

Engineering Contradiction:
Improveviscosity increase due to nucleic acid releaseVSAvoidproduction cost and industrial scalability
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The invention changes the pH parameter to a highly alkaline range (pH 12.0 to 14.0) and combines it with oxidizer treatment to achieve nucleic acid degradation. This parameter change enables effective viscosity reduction while avoiding the need for expensive commercial nucleases, making the process suitable for industrial-scale production.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses strong oxidizers (such as hydrogen peroxide, sodium peroxide, or peracetic acid) to accelerate the degradation of nucleic acids in the highly alkaline environment. This oxidation mechanism efficiently breaks down nucleic acids, reducing viscosity without requiring expensive enzymatic treatments, thereby lowering production costs and improving industrial scalability.

Inventive Principle:
Principle #38Strong oxidants (Accelerated oxidation)

2Object-affected harmful factors

If pH is adjusted to reduce viscosity, then nucleic acid degradation is improved, but molecular weight of PHA may be reduced

Engineering Contradiction:
Improvenucleic acid degradation efficiencyVSAvoidPHA molecular weight control
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The invention performs preliminary inactivation of the microorganism before pH adjustment and oxidizer addition. This preliminary step prevents ongoing metabolic activity that could otherwise lead to PHA degradation, thereby protecting molecular weight while allowing subsequent pH and oxidation treatments to effectively degrade nucleic acids and reduce viscosity.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention carefully controls the combination of highly alkaline pH (12.0-14.0) and oxidizer concentration to achieve selective degradation. By optimizing these parameters, the process preferentially degrades nucleic acids while minimizing impact on PHA molecular weight, thus resolving the contradiction between viscosity reduction and molecular weight preservation.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If microorganism is inactivated, then PHA production is complete, but nucleic acids are released causing high viscosity

Engineering Contradiction:
ImprovePHA production completionVSAvoidculture solution viscosity
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The invention converts the harmful effect of nucleic acid release (which causes high viscosity) into a beneficial outcome by using the released nucleic acids as substrates for oxidation. The highly alkaline environment combined with oxidizers transforms the problematic nucleic acids into degraded products, effectively converting the harm of inactivation into a solution for viscosity reduction.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

By introducing strong oxidizers into the inactivated culture, the invention accelerates the breakdown of released nucleic acids. This oxidation process rapidly degrades the viscous nucleic acid polymers into smaller fragments, effectively reducing culture solution viscosity as a direct consequence of the inactivation process itself.

Inventive Principle:
Principle #38Strong oxidants (Accelerated oxidation)

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 method allows for the efficient reduction of culture solution viscosity, enabling cost-effective industrial-scale production of polyhydroxyalkanoates with desired molecular weights, reducing the need for additional enzymes and surfactants, and minimizing plastic waste, thus contributing to sustainable development goals.

Implementation Method 1

adding an oxidizer to a culture solution containing a PHA-producing microorganism which has been inactivated

Methodology Applied
Scientific EffectOxidation: Oxidation

Implementation Method 2

adjusting the pH to a specific pH

Methodology Applied
Scientific EffectpH adjustment:

Implementation Method 3

maintaining a specific temperature

Methodology Applied
Scientific EffectThermal treatment: Heating

Data Source

PatentUS20240336942A1Method for producing polyhydroxyalkanoic acid and use of same
Publication Date: 2024.10.10 KANEKA CORP

AI summary

It is an object of an embodiment of the present invention to provide an industrially easily applicable technology for reducing a viscosity of a culture solution, in order to collect a polyhydroxyalkanoate from a polyhydroxyalkanoate-producing microorganism. The object is attained by providing a method for producing a polyhydroxyalkanoate, including the following steps (a) and (b): (a) maintaining a culture solution at 40° C. to 80° C., the culture solution including microbial cells containing the polyhydroxyalkanoate; and (b) adding an oxidizer to the culture solution obtained in the step (a), adjusting a pH of the culture solution to 10.5 to 13.0, and maintaining the culture solution at 30° C. to 75° C.