Bacillus cereus Detection Kit Using Fluorescent PC-PLC Substrate
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Solution Overview
Problem
Current methods for detecting and counting Bacillus cereus group bacteria are hindered by false positives and negatives, long detection times, and the need for complex inhibitor systems, which complicates rapid and accurate identification in both food-processing and clinical diagnostics.
Innovation Solution
A method using a reaction medium with a fluorescent PC-PLC substrate and an inhibitor for Gram-negative bacteria, optimized for pH 6.8-8.0 and a detection time of 6-30 hours, allowing for rapid and specific detection of Bacillus cereus group bacteria by adapting the pH and time for the hydrolysis reaction to distinguish them from other Gram-positive bacteria.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional selective plating culture media (PEMBA or MYP) are used for detection, then the detection process is simple, but false positives and false negatives occur due to ineffective inhibitor systems and absence of key characteristics in certain strains
Solution Approach 1:
The patent changes the chemical parameters of the culture medium by incorporating specific chromogenic substrates (such as X-CP or 5-bromo-4-chloro-3-indoxyl-beta-D-galactopyranoside) that undergo colorimetric changes when hydrolyzed by specific bacterial enzymes. This allows for reliable differentiation of Bacillus cereus group bacteria based on enzymatic activity patterns, eliminating false positives and negatives while maintaining media simplicity
Solution Approach 2:
The patent introduces chromogenic substrates as intermediary compounds that mediate between bacterial enzymatic activity and visual detection. These substrates serve as specific markers that produce distinct color reactions for different bacterial groups, enabling accurate identification without complex inhibitor cocktails or multiple testing steps
2Reliability
If inhibitor cocktails are added to improve specificity, then false positives are reduced, but the growth of target microorganisms is delayed
Solution Approach 1:
The patent extracts and eliminates the need for complex inhibitor cocktails by relying on the inherent selective properties of chromogenic substrates. The substrates themselves provide specificity through their enzymatic hydrolysis patterns, allowing target bacteria to grow and express their diagnostic characteristics without time-consuming inhibition steps
Solution Approach 2:
The patent incorporates chromogenic substrates into the culture medium beforehand, so that as soon as target bacteria grow and express their specific enzymatic activities, immediate colorimetric differentiation occurs. This preliminary preparation of the medium with diagnostic substrates eliminates the need for subsequent inhibitor addition and waiting periods
3Productivity
If chromogenic plating media with multiple substrates are used to improve detection speed, then results are obtained faster, but false positives increase due to cross-reactions
Solution Approach 1:
The patent applies local quality by using specific chromogenic substrates targeted at particular enzymatic activities characteristic of Bacillus cereus group bacteria. Rather than using multiple general substrates that could cross-react, the method employs substrates with specific affinity for key bacterial enzymes, producing localized and specific colorimetric responses that maintain both speed and accuracy
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 approach significantly reduces false positives and negatives, improves sensitivity for low contamination levels, and simplifies the detection process with easy, automated reading, enabling faster and more accurate identification of Bacillus cereus group bacteria.
Implementation Method 1
a reaction medium with a fluorescent PC-PLC substrate and an inhibitor for Gram-negative bacteria, optimized for pH 6.8-8.0 and a detection time of 6-30 hours, allowing for rapid and specific detection of Bacillus cereus group bacteria by adapting the pH and time for the hydrolysis reaction
Implementation Method 2
A method using a reaction medium with a fluorescent PC-PLC substrate
Data Source
AI summary
The present invention relates to the field of microbiological testing of food. It relates to a kit comprising a reaction medium containing at least one inhibitor of Gram-negative bacteria and a fluorescent substrate specific for PC-PLC. It further relates to a diagnostic kit for identifying bacteria of the Bacillus cereus group comprising a container of a selective or nonselective reaction medium with a pH between 6.8 and 8.0, the medium comprising at least one inhibitor of Gram-negative bacteria and a fluorescent phosphatidylcholine phospholipase C (PC-PLC) substrate.