RT-PCR Pre-rRNA Assay for Viable Microbial Detection
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Solution Overview
Problem
Current methods for distinguishing viable from non-viable microbial cells in preservative efficacy testing are time-consuming and fail to detect viable but non-cultivable cells, with existing molecular methods not clearly differentiating between viable and non-viable organisms after treatment with preservatives.
Innovation Solution
A method and kit using reverse transcription-polymerase chain reaction (RT-PCR) to amplify and quantify species-specific DNA from precursor rRNA (pre-rRNA) in microbial samples, employing primers and probes specific to pre-rRNA regions, which indicates the presence and quantity of viable microbial cells by comparing treated and untreated samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional microbiological culture methods are used for PET assessment, then results can be obtained through standard procedures, but the time to results is very long and viable but non-cultivable cells are not detected
Solution Approach 1:
The patent replaces conventional microbiological culture methods (mechanical/growth-based system) with molecular biology methods (RT-PCR and RNA sequencing) to detect pre-rRNA and mRNA transcripts. This substitution enables direct molecular detection of viable cells without requiring culturing, thereby significantly reducing time to results while improving detection accuracy including viable but non-cultivable cells
Solution Approach 2:
The patent changes the detection parameter from growth-based metrics (colony formation) to molecular biomarkers (pre-rRNA and mRNA transcript levels). By measuring transcript abundance and metabolic activity markers instead of growth, the method achieves faster results and detects cells that cannot be cultured, resolving the contradiction between reliability and time
2Reliability
If RT-PCR assays targeting microbial rRNA are used, then molecular detection is achieved, but the ability to clearly distinguish viable from non-viable organisms after treatment with preservatives is limited
Solution Approach 1:
The patent applies local quality by selecting specific RNA targets (pre-rRNA and mRNA) that are locally indicative of viability rather than using general rRNA detection. Pre-rRNA represents active ribosome biogenesis in viable cells, and mRNA indicates metabolic activity, providing localized molecular signatures that precisely distinguish viable from non-viable cells after preservative treatment
Solution Approach 2:
The patent uses pre-rRNA and mRNA transcripts as intermediary biomarkers that mediate between cellular viability status and detectable signals. These RNA molecules serve as intermediaries that reflect metabolic activity and ribosomal function, providing a precise indirect measure of viability that overcomes the limitations of direct rRNA detection
3Reliability
If ratiometric pre-rRNA analysis with two sample sets is used, then viable cell detection is improved, but the device complexity and procedure complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-processing samples with nutrient stimulation before RNA extraction and analysis. This preliminary step induces pre-rRNA accumulation in viable cells, creating a baseline enhancement that simplifies subsequent detection and reduces the need for complex ratiometric comparisons, thereby maintaining reliability while reducing procedural complexity
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 the time to results, detects viable but non-cultivable cells, and provides a clear distinction between viable and non-viable cells, with a ΔCt value of ≥10 indicating effective preservative treatment, thereby improving the accuracy and efficiency of preservative efficacy testing.
Implementation Method 1
A method and kit using reverse transcription-polymerase chain reaction (RT-PCR) to amplify and quantify species-specific DNA from precursor rRNA (pre-rRNA) in microbial samples
Implementation Method 2
using a fluorescently labeled hybridizing probe complementary to the mature rRNA region of the microorganism of interest, and performing multiple cycles of amplification using the fluorescently labeled hybridizing probe and the first and the second primers to yield increasing levels of fluorescence signal
Data Source
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AI summary
Methods and kits are disclosed for distinguishing viable from nonviable microbial cells. The methods and kits are useful in the screening of cell culture formulations and the testing of preservative efficacy. The methods involve the amplification and quantitation of microbe-specific DNA from precursor rRNA or Elongation Factor 3 mRNA in treated versus nontreated test samples using the reverse transcription polymerase chain reaction.