Yeast Medium Acidification Below pKa for Microbial Contamination Control

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Solution Overview

Problem

Microbial contamination in yeast media used for bioethanol production leads to yeast performance inhibition and reduced ethanol yield, necessitating the use of antibiotics that promote antibiotic-resistant strains and pose regulatory and consumer concerns.

Innovation Solution

A process involving the use of an antimicrobial composition comprising weak acids, optionally combined with strong acids and acid-stable bacteriocins, to adjust the pH of the yeast medium below the pKa of the weak acid, maintaining the acidified medium to inhibit microbial activity, and potentially incorporating recombinant yeast and lactic acid bacteria for enhanced fermentation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If antibiotics are used to control microbial contamination, then microbial activity is inhibited, but antibiotic-resistant strains emerge and regulatory concerns arise

Engineering Contradiction:

Improvemicrobial contamination controlVSAvoidantibiotic resistance and residues

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical parameters of the medium by adjusting pH to below the pKa of weak acids (creating acidic conditions) and controlling redox potential, thereby creating an environment that inhibits microbial growth without using antibiotics. This parameter change approach replaces chemical antibiotics with physical-chemical conditions to achieve the same antimicrobial effect while avoiding resistance development.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of acidic conditions (which would normally inhibit yeast growth) into a beneficial tool by carefully controlling pH to be below the pKa of weak acids, creating an environment that selectively inhibits contaminating microbes while allowing yeast to thrive. The harmful acidity is thus transformed into a selective antimicrobial agent.

Inventive Principle:

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

2Reliability

If pH is adjusted below pKa of weak acid to inhibit microbial activity, then contaminating microbes are suppressed, but yeast performance may be affected

Engineering Contradiction:

Improvemicrobial contamination controlVSAvoidyeast performance

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies different conditions to different microbial populations: the acidic environment (pH below pKa) selectively affects contaminating bacteria while the yeast, being more acid-tolerant, maintains its performance. This local quality approach creates selective pressure against contaminants while preserving yeast function through differential sensitivity to the acidic conditions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent dynamically adjusts multiple parameters including pH, redox potential, and nutrient composition to create conditions that are inhibitory to contaminants at critical stages while remaining favorable for yeast growth and fermentation. The system is continuously optimized to maintain the balance between antimicrobial activity and yeast performance.

Inventive Principle:

Principle #15Dynamics

3Reliability

If redox potential is controlled to reduce microbial contamination, then contaminating microbes are inhibited, but process complexity increases

Engineering Contradiction:

Improvemicrobial contamination controlVSAvoidprocess control

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple control functions into a unified approach by simultaneously managing pH and redox potential as interconnected parameters. Rather than treating them as separate control systems, the method integrates them into a single antimicrobial strategy where acidic conditions and reduced redox potential work synergistically to inhibit contaminants, simplifying overall process control despite the multi-parameter nature of the solution.

Inventive Principle:

Principle #5Merging (Combining)

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

Reduces microbial contamination, minimizes the need for antibiotics, and enhances fermentation yield by maintaining yeast viability and activity, thereby increasing ethanol production.

Implementation Method 1

adjusting the pH of a raw medium with a strong acid to provide an acidified medium

Methodology Applied

Scientific EffectpH adjustment:

Implementation Method 2

maintaining the acidified medium at the adjusted pH for a period of time

Methodology Applied

Scientific EffectAcidification:

Implementation Method 3

reduce the activity associated with microbial contamination that may be present in a yeast medium

Methodology Applied

Scientific EffectMicrobial inhibition:

Data Source

PatentUS12441976B2Process for reducing the activity of microbial contamination in a yeast medium

Publication Date: 2025.10.14 DANSTAR FERMENT AG

AI summary

The present disclosure provides an antimicrobial composition as well as a process using same to limit microbial activity in a yeast medium. The antimicrobial composition includes at least one weak acid, optionally in combination with an acid stable bacteriocin and/or an antibiotic. The antimicrobial composition can be used for propagating yeasts and for making a fermentation product. The present disclosure also provides yeasts and lactic acid bacteria that can be used with the antimicrobial composition.