Bacterial Cell Cultivability Quantification via Fluorescence Microscopy
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Solution Overview
Problem
Current microbiology methods for bacterial cell counting, such as traditional culturing, are slow and unable to detect viable non-cultivable cells, leading to inefficiencies in healthcare and manufacturing, while faster methods sacrifice sensitivity and the ability to select cultivable cells.
Innovation Solution
A method using nucleic acid content and cell stretching parameters to classify microbial cells into viable cultivable, viable non-cultivable, and dead categories through fluorescence microscopy and cytometry, providing rapid and reliable quantification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional microbial culturing method is used, then sensitivity and cultivable cell selection are maintained, but time-to-result is too long (over 24 hours)
Solution Approach 1:
The method segments the traditional culturing process by using fluorescent dyes to directly stain and visualize individual bacterial cells, separating the detection function from the growth function. This allows rapid identification of viable cells without waiting for colony formation, reducing time-to-result while maintaining sensitivity through direct cellular observation.
Solution Approach 2:
The invention replaces the mechanical/biological process of bacterial growth and colony formation with an optical detection system using fluorescent microscopy. By substituting the time-consuming biological amplification (cell division) with immediate optical detection of fluorescently labeled cells, the method achieves rapid results while preserving the ability to distinguish viable from non-viable cells.
2Loss of time
If rapid methods like PCR or antigen-antibody testing are used, then time-to-result is reduced (4-8 hours), but sensitivity and cultivable cell selection capability are sacrificed
Solution Approach 1:
The method uses fluorescent dyes that produce distinct color signals (green for viable cells, red for non-viable cells) to enable rapid visual differentiation of bacterial viability. This optical signaling system provides immediate results within minutes to hours, far faster than PCR or antigen testing, while maintaining the ability to select and count only cultivable viable cells through direct visualization.
Solution Approach 2:
The invention changes the detection parameter from molecular amplification (PCR) or antigen-antibody binding to fluorescent staining intensity and cellular morphology. By measuring fluorescence intensity ratios and cell shape parameters directly, the method achieves rapid results while preserving sensitivity to detect individual viable cells that can be cultured, avoiding the loss of cultivable cell selection inherent in molecular methods.
3Loss of time
If LIVE/DEAD BacLight staining is used, then rapid differentiation between viable and non-viable cells is achieved, but interpretation difficulties arise due to intermediate physiological states
Solution Approach 1:
The method introduces asymmetry in the staining protocol by using different staining intensities and combinations for different cell types. Viable cells show strong green fluorescence with specific morphological features, while non-viable cells show red fluorescence. This asymmetric signaling pattern, combined with morphology analysis, resolves the ambiguity of intermediate states by providing distinct, easily distinguishable signatures for each cell category.
Solution Approach 2:
The invention adds a morphological dimension to the fluorescent staining analysis. By combining fluorescence intensity measurements with cellular shape, size, and structural parameters observed under microscopy, the method creates a multi-dimensional classification system. This additional dimensional information clearly separates viable from non-viable cells, eliminating the interpretation difficulties of intermediate physiological states that plague single-parameter fluorescent methods.
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 enables rapid bacterial cell counting within 4 hours, retaining sensitivity and cultivable cell selection, effectively addressing the limitations of traditional culturing by autonomously quantifying microbial populations in various samples.
Implementation Method 1
contacting the sample with a nucleic acid binding fluorescent dye to stain cellular nucleic acids in said microbial cells
Data Source
AI summary
The invention relates to the field of microbiology and detecting micro-organism. Provided is a method for the quantitative analysis of microbial cells in a liquid sample, comprising the steps of (i) contacting the sample with a nucleic acid binding fluorescent dye to stain for nucleic acids in said microbial cells; (ii) subjecting the labelled cells to a fluorescence microscopy imaging method and determining, based on the nucleic acid staining, for a plurality of single cells at least a first parameter reflecting the nucleic acid content of said cell and a second parameter reflecting the extent of stretching of said cell; (iii) classifying based on said at least first and second parameter said cell into one of the following categories: (A) Viable cultivable cells with a nucleic acid content value between >=0.1 and <1.0 and extent of stretching of the cell value between >=1.0 and 10 μιηm2, (B) Viable non-cultivable cells with a nucleic acid content value of >−0.2 and extent of stretching of the cell value of >=0.5 μιηm2 minus (A), (C) Most likely dead cells with a nucleic acid content of <1.0 and extent of stretching of the cell value of <0.50 μιηm2; and (iv) calculating the ratio of the amount of (A) viable cultivable cells, (B) viable non-cultivable cells and (C) most likely dead cells in a microbial sample.