Dry Hydrogel Culture Device for Rapid Aerobic Bacteria Detection
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Solution Overview
Problem
Conventional methods for enumerating aerobic bacteria, such as pour-plate and thin film culture devices, are time-consuming and require at least 48 hours for accurate results, leading to extended storage times for food products and increased costs.
Innovation Solution
A dry, reconstitutable culture device with a plurality of indicator agents, including enzyme activity indicators and a redox indicator, that allows for the rapid detection and enumeration of aerobic bacteria within 48 hours or less, utilizing a self-supporting substrate sheet, cover sheet, and a cold-water-soluble hydrogel-forming composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional agar culture media are used for aerobic bacteria enumeration, then accurate quantitative results can be obtained, but the incubation period requires at least 48 hours, leading to extended storage times and increased costs
Solution Approach 1:
The patent changes the chemical parameters of the culture medium by incorporating specific indicator agents (chromogenic substrates for enzyme activities and redox indicators) that enable rapid detection. This allows the incubation period to be reduced from 48+ hours to 24-36 hours while maintaining accurate quantitative results through enhanced visual detection capabilities.
Solution Approach 2:
The patent employs color-changing indicator agents that undergo chromogenic or fluorogenic transformations when interacted with bacterial enzymes. These color changes provide rapid visual detection of bacterial presence and activity, enabling shorter incubation periods while maintaining measurement accuracy through enhanced detection sensitivity.
2Productivity
If conventional agar medium is used, then aerobic bacteria can be cultured and enumerated, but the process is time-consuming and requires extended storage of food products
Solution Approach 1:
The patent incorporates all necessary indicator agents and nutrients into the culture medium in advance during manufacturing. The medium is prepared with pre-included chromogenic substrates, redox indicators, and nutrient compounds, eliminating the need for time-consuming preparation steps during testing and enabling rapid results within 24-36 hours.
Solution Approach 2:
The patent creates a composite culture medium combining traditional nutrients with specific indicator agents (chromogenic substrates for glycosidase, protease, lipase, phosphatase, and redox indicators). This composite formulation enables simultaneous bacterial growth and rapid detection, reducing the overall testing time and extending food product shelf life.
3Adaptability or versatility
If multiple indicator agents are used to detect various enzyme activities, then a wide variety of aerobic bacteria can be detected, but the device complexity increases
Solution Approach 1:
The patent designs a universal culture medium formulation that simultaneously supports detection of multiple bacterial groups through a standardized set of indicator agents. The medium contains chromogenic substrates for major enzyme categories (glycosidase, protease, lipase, phosphatase) and redox indicators, allowing a single device to detect diverse aerobic bacteria including lactic acid bacteria, Enterobacteriaceae, and Pseudomonads without requiring separate specialized media.
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
Enables rapid detection and enumeration of aerobic bacteria, reducing storage times and costs for food products without compromising product quality, by providing a more efficient method for culturing and detecting microorganisms.
Implementation Method 1
a first layer comprising a substantially dry, cold-water-soluble first hydrogel-forming composition adhered to the first major surface of the substrate sheet
Implementation Method 2
The plurality of indicator agents can comprise three enzyme activity indicator reagents for detecting distinct glycosidase enzyme activities, an enzyme activity indicator reagent for detecting an alkyl esterase enzyme activity, and an enzyme activity indicator reagent for detecting a phosphatase enzyme activity
Implementation Method 3
a redox indicator comprising a tetrazolium dye
Data Source
AI summary
A thin film culture device for detecting aerobic bacteria in a sample is provided. The culture device comprises a self-supporting substrate sheet having a first major surface and a second major surface; a cover sheet attached to the substrate sheet, a sample-receiving zone disposed between the substrate sheet and the cover sheet, a first layer comprising a substantially dry, cold-water-soluble first hydrogel-forming composition adhered to a portion of the sample-receiving zone; and a plurality of indicator agents disposed in at least one layer adhered to the substrate sheet or the cover sheet. The plurality of indicator agents comprises three indicator agents for detecting distinct glycosidase enzyme activities, an indicator agent for detecting an alkyl esterase enzyme activity, an indicator agent for detecting a phosphatase enzyme activity, and a redox indicator. A method of using the culture device is also provided.