Cytofluorometry of Freeze-Dried Bacterial Cells for Viability Assessment
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Solution Overview
Problem
Current methods for determining the concentration and viability of freeze-dried bacterial cells are laborious, unreliable, and lack standardization, leading to uncertainties in producing stable and effective probiotic products, especially in varying climatic conditions.
Innovation Solution
A cytofluorometry method is applied to evaluate the integrity of the cell wall of freeze-dried bacterial cells, involving fermentation, concentration, cryoprotection with phosphorous salts and polyhydroxy substances, and freeze-drying to ensure cell stability and viability, measured in active fluorescent units (AFU).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plate count method is used to determine bacterial cell concentration and viability, then traditional methodology is applied, but the method is laborious, time-consuming (72 hours incubation), and lacks precision and reproducibility
Solution Approach 1:
The patent replaces the mechanical/cultural plate count method with a cytofluorometry-based optical detection system. This substitution enables rapid, automated, and precise measurement of bacterial cell concentration and viability without requiring incubation periods, thereby resolving the contradiction between productivity and measurement precision.
Solution Approach 2:
The invention changes the measurement parameter from colony-forming units (CFU) requiring incubation to fluorescence intensity signals detectable immediately. By using fluorescent dyes that bind to cellular components and measuring their fluorescence properties, the method achieves rapid and precise quantification, eliminating the 72-hour incubation requirement while improving reproducibility.
2Reliability
If plate count method is used, then traditional approach is followed, but viable but non-culturable cells (VBNC) are underestimated and aggregates give only one colony
Solution Approach 1:
The patent replaces the cultivation-based plate count method with a direct optical detection method using cytofluorometry. This substitution allows detection of all intact cells including VBNC cells and individual cells within aggregates, providing accurate and complete quantification without the limitations of colony formation requirements.
Solution Approach 2:
The invention utilizes fluorescent dyes that produce color/fluorescence changes when binding to cellular components. Different dyes can distinguish between viable and non-viable cells based on their fluorescence properties, enabling accurate detection and quantification of all intact cells regardless of their culturable status, thereby improving reliability and eliminating underestimation.
3Stability of the object's composition
If freeze-drying is performed without proper cryoprotection, then cell wall integrity is compromised, but adding protective agents is required to maintain stability
Solution Approach 1:
The patent applies cryoprotective agents to the bacterial cells before freeze-drying to prevent cell wall damage during the process. This preliminary protective action ensures cell wall integrity is maintained throughout freeze-drying and storage, resolving the contradiction between maintaining stability and avoiding excessive complexity by using well-established protective protocols.
Solution Approach 2:
The invention uses cryoprotective agents as intermediary substances that mediate between the cells and the harsh freeze-drying conditions. These agents form a protective matrix around the cells, preventing direct damage from freezing and desiccation, thereby maintaining cell wall integrity while keeping the process relatively simple and controllable.
4Adaptability or versatility
If different internal count methods are used by different companies, then company-specific protocols are applied, but comparison and confirmation of bacterial strain concentration in finished products becomes difficult
Solution Approach 1:
The patent employs cytofluorometry as a universal measurement platform that can be applied across different bacterial strains and product types. This universal method produces standardized, comparable results that can be consistently used across different laboratories and companies, eliminating the comparability issues associated with company-specific protocols while maintaining adaptability to various probiotic organisms.
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 method provides a reliable, repeatable, and precise assessment of cell wall integrity, resulting in a stable and viable biomass with prolonged shelf-life and enhanced effectiveness, applicable across different bacterial strains and climatic zones.
Implementation Method 1
The method involves placing at contact the fermented biomass, the concentrated biomass, the cryoprotected biomass and/or the freeze-dried biomass with at least one fluorescent dye
Implementation Method 2
mixing the concentrated biomass obtained from step (ii) with a solution comprising... to obtain a cryoprotected biomass of bacterial cells (cryoprotected biomass); (iv) freeze-drying the cryoprotected biomass obtained from step (iii) to obtain the freeze-dried biomass
Data Source
AI summary
A method applying cytofluorometry to a biomass of freeze-dried bacterial cells (freeze-dried biomass) is described. The method is performed for evaluating the stability of said freeze-dried bacterial cells. Methods applying cytofluorometry to preparation of a freeze-dried biomass, and for evaluating the integrity of a cell wall present in freeze-dried bacterial cells are also described.