Bacillus Cereus Detection Medium Without Egg Yolk Cross-Reactivity

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Solution Overview

Problem

Existing media for Bacillus cereus detection face challenges such as insufficient growth of Bacillus cereus in 24 hours, false positives with Staphylococcus, and cross-reactivity with Listeria monocytogenes, necessitating a medium that enhances growth and selectivity without egg yolk reaction.

Innovation Solution

A medium incorporating a phosphatidylinositol-specific phospholipase C substrate with a chromogenic or fluorescent free radical and trimethoprim, optionally with a β-lactam antibiotic and antifungal agent, to enhance Bacillus cereus growth while inhibiting other microorganisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If egg yolk-containing medium is used for Bacillus cereus detection, then detection capability is improved, but preparation complexity increases due to multiple temperature control steps

Engineering Contradiction:

Improvedetection capabilityVSAvoidpreparation complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the egg yolk component from the detection medium, replacing it with alternative substances that provide the necessary detection functionality without requiring complex temperature control during preparation. This removes the problematic preparation steps while maintaining detection capability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the chemical composition parameters of the medium by substituting egg yolk with different substances, thereby altering the preparation conditions to eliminate temperature-sensitive steps while preserving the detection function for Bacillus cereus.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If egg yolk is added to the medium, then detection principle is enhanced, but thermal denaturation risk increases requiring extreme temperature control

Engineering Contradiction:

Improvedetection principleVSAvoidthermal denaturation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes the egg yolk substance that is susceptible to thermal denaturation, replacing it with thermally stable alternatives that do not require extreme temperature control during addition, thereby eliminating the harmful thermal effects while maintaining detection functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If collected egg yolk is used for detection, then egg yolk reaction is utilized, but medium performance varies due to hen individual differences

Engineering Contradiction:

Improvedetection consistencyVSAvoidmedium performance stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent extracts and removes the biological variable (egg yolk) that causes performance variation due to hen individual differences, replacing it with a standardized, chemically defined substance that provides consistent medium performance across different preparations and laboratories.

Inventive Principle:

Principle #2Taking out (Extraction)

4Reliability

If existing medium formulations are used, then detection is possible, but false positives occur with Staphylococcus and Listeria monocytogenes

Engineering Contradiction:

Improvedetection abilityVSAvoiddetection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by modifying specific components of the medium formulation to create selective zones of inhibition or enhancement that allow Bacillus cereus to be detected while preventing false positives from Staphylococcus and Listeria monocytogenes, thereby improving detection accuracy without sacrificing detection ability.

Inventive Principle:

Principle #3Local quality

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 medium allows accurate, efficient, and easy discrimination of Bacillus cereus in the presence of various microorganisms, with improved growth and selectivity, suitable for food and environmental testing.

Implementation Method 1

a phosphatidylinositol-specific phospholipase C substrate having a detectable chromogenic or fluorescent free radical

Methodology Applied

Scientific EffectEnzymatic hydrolysis: Hydrolysis

Implementation Method 2

having a detectable chromogenic or fluorescent free radical

Methodology Applied

Scientific EffectChromogenic reaction:

Implementation Method 3

having a detectable chromogenic or fluorescent free radical

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 4

trimethoprim... to enhance Bacillus cereus growth while inhibiting other microorganisms

Methodology Applied

Scientific EffectAntimicrobial inhibition:

Data Source

PatentUS12618095B2Medium for <i>Bacillus cereus </i>group detection

Publication Date: 2026.05.05 SHIMADZU DIAGNOSTICS CORP

AI summary

A medium for Bacillus cereus group detection, which is favorable in growth of Bacillus cereus regardless of the temperature condition, and further is excellent in selectivity; and a method for detecting a Bacillus cereus group using the medium. The medium for Bacillus cereus group detection includes a phosphatidylinositol-specific phospholipase C substrate having a detectable chromogenic or fluorescent free radical; and trimethoprim. The medium further includes a β-lactam antibiotic. The medium further includes an antifungal agent. The method for detecting further includes inoculating a sample into the medium to culture the sample; and determining a detectable colony on the medium.