Cold Water-Soluble Gel Medium for Large-Volume Microbe Counting
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Solution Overview
Problem
Existing methods for enumerating low levels of target organisms in large volumes of test samples, such as water and food, are laborious, time-consuming, or require expensive equipment, and are not suitable for turbid samples, especially when dealing with low water activity foods that are toxic to bacteria.
Innovation Solution
A method using a cold water-soluble gelling agent, such as glucomannan, to form a gelable medium with a nutrient base in the sample, allowing for microbial growth and colony formation, enabling direct enumeration of target organisms without filtering or concentrating the sample.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If MPN procedure is used to enumerate low levels of target organisms in large volumes, then the method can handle large sample volumes, but the measurement precision is poor and the process is laborious and time-consuming
Solution Approach 1:
The patent changes the physical state of the medium from liquid to gel by adding a gelling agent, which allows large volumes of sample to be processed while maintaining precise colony counting capability. The gel matrix provides a stable platform for colony formation and visualization, resolving the contradiction between handling large volumes and achieving precise measurements.
Solution Approach 2:
The patent creates a composite medium system combining nutrient base media with a gelling agent to form a gel matrix. This composite structure enables the medium to maintain its physical properties over large volumes while providing optimal conditions for microbial growth and enumeration, thereby achieving both large sample capacity and precise measurement.
2Measurement precision
If membrane filter technique is used to enumerate low levels of target organisms, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the complex filtration apparatus requirement from the enumeration process. By using a gelable medium that can be directly poured or spread in a liquid state and then gelled in situ, the method achieves precise enumeration without needing membrane filters or complex filtration equipment, thereby simplifying the device requirements while maintaining measurement precision.
Solution Approach 2:
The patent employs a disposable gel medium system that can be prepared and used in a simple, cost-effective manner. The gel matrix is formed directly in the sample container and does not require expensive filtration apparatus, making the overall system more economical and accessible while maintaining precise enumeration capability.
3Ease of manufacture
If conventional gel media are used, then colony formation is visible, but heating and divalent cations are required which increases complexity
Solution Approach 1:
The patent changes the gelling mechanism from thermal or chemical (requiring heating and divalent cations) to a cold-water-soluble gel system that gels at ambient temperatures. This parameter change eliminates the need for heating equipment and cation additives, simplifying the manufacturing process while maintaining clear colony visibility through the gel matrix.
Solution Approach 2:
The patent replaces the thermal heating mechanism with a cold-water-soluble gelling system that operates at ambient temperatures. This substitution eliminates the need for heating equipment and complex chemical conditioning, thereby reducing device complexity and ease of manufacture requirements while preserving the ability to produce visible colonies for enumeration.
4Object-affected harmful factors
If spices are diluted to neutralize toxicity, then bacteria can grow, but sample size increases significantly
Solution Approach 1:
The patent introduces a gelable medium as an intermediary substance that neutralizes the toxicity of spices while maintaining a manageable sample volume. The gel matrix acts as a protective environment that allows bacterial growth on spices without requiring extensive dilution, thereby reducing the final sample volume needed for enumeration while still neutralizing harmful effects.
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
Provides rapid and accurate enumeration of low levels of target organisms in large volumes by forming a uniform gel that softens after a few days, facilitating efficient disposal and reducing costs, while eliminating the need for heating and divalent cations, suitable for both clear and turbid samples.
Implementation Method 1
forming, in the container, a gelled layer of the dissolved medium within a gelling time period of less than 1 hour after dissolution of the gelling agent component in the liquid test sample
Implementation Method 2
gelable, cold water-soluble microbiological medium
Data Source
AI summary
Provided are methods for enumerating target microorganisms in a test sample, comprising: retaining a liquid test sample having dissolved therein a nutrient base media component and a glucomannan-containing gelling agent component of a solid cold water-soluble microbiological medium; forming a gelled layer of the dissolved medium; incubating the gelled layer under conditions sufficient for microbial growth and detectable colony formation in and/or on the gelled layer; and enumerating a number of target microorganisms in the test sample by counting the colonies. Preferred gelling agents comprises 5-7 g glucomannan per 100 ml liquid test sample, and optionally comprise a gum(s). Compositions, kits and combinations comprising a nutrient base media and a glucomannan-containing gelling agent, are also provided. The compositions and methods enable enumerating a small number of target microorganisms (e.g., <1 cell/mL) in a large volume (e.g., 50 ml to 150 mL or larger) of a liquid test sample.