DNA Extraction Precipitant Composition for Food-Matrix PCR Purity
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Solution Overview
Problem
Conventional DNA extraction methods from emulsified foods, such as dairy products, are inefficient due to PCR inhibitors like proteins and fats, leading to low recovery rates and false-positive results in microbial detection.
Innovation Solution
A precipitant composition comprising 1.3-2.1% phosphotungstic acid hydrate, 1.2-1.8% zinc acetate dihydrate, and 13.0-19.0% acetic acid is used to remove impurities during DNA extraction, followed by a method involving cell lysis, silica membrane column processing, and specific buffers for high-purity DNA extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DNA extraction methods are used from emulsified foods, then the extraction process is simple, but the recovery rate is low and PCR inhibitors remain
Solution Approach 1:
The patent applies preliminary action by adding the precipitant composition (containing phosphotungstic acid hydrate, zinc acetate dihydrate, and acetic acid) to the lysate before DNA binding to the silica membrane. This pre-precipitation step removes PCR inhibitors (proteins, fats, calcium) from the sample, ensuring that the DNA bound to the column is free from contaminants that would interfere with subsequent PCR analysis, thereby improving both purity and recovery rate
Solution Approach 2:
The precipitant composition acts as an intermediary substance between the complex food matrix and the DNA extraction process. The specific combination of phosphotungstic acid hydrate, zinc acetate dihydrate, and acetic acid creates a chemical environment that selectively precipitates inhibitors while leaving DNA in solution, facilitating clean separation and binding of DNA to the silica membrane without co-precipitation of contaminants
2Reliability
If phenol/chloroform extraction is used, then DNA can be separated, but the process is time-consuming and requires harmful reagents
Solution Approach 1:
The patent replaces the reusable but hazardous phenol/chloroform system with a disposable silica membrane column containing a precipitant composition. The column is single-use, eliminating the need for repeated handling of harmful reagents, while the precipitant composition (phosphotungstic acid hydrate, zinc acetate dihydrate, acetic acid) provides effective DNA separation without the safety concerns of phenol and chloroform
Solution Approach 2:
The patent substitutes the chemical extraction mechanism of phenol/chloroform with a combined chemical-physical approach using the precipitant composition followed by silica membrane binding. The precipitant chemically precipitates inhibitors, while the silica membrane provides physical adsorption of DNA, replacing the need for organic solvent-based phase separation
3Productivity
If column-based DNA extraction is used, then the process is fast and convenient, but inhibitors from food are not effectively removed
Solution Approach 1:
The patent maintains the fast and convenient column-based extraction format while adding a preliminary precipitation step. The precipitant composition (phosphotungstic acid hydrate, zinc acetate dihydrate, acetic acid) is added to the lysate before loading onto the silica column, pre-removing inhibitors so that the DNA binding step is not compromised by contaminant interference, thus preserving speed while improving reliability
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 achieves high-concentration and high-purity DNA extraction, enabling accurate detection of microbes at low concentrations, improving the limit of detection to 2×101 CFU/mL, and ensuring effective PCR analysis.
Implementation Method 1
a precipitant composition comprising 1.3-2.1% phosphotungstic acid hydrate, 1.2-1.8% zinc acetate dihydrate, and 13.0-19.0% acetic acid is used to remove impurities during DNA extraction
Implementation Method 2
followed by a method involving cell lysis, silica membrane column processing, and specific buffers for high-purity DNA extraction
Data Source
AI summary
There is provided an impurity precipitant composition used for precipitating and removing impurities that inhibit the pure separation of DNA during the process of extracting DNA by lysis of cells in a sample. The composition includes 1.3-2.1% (w/v) phosphotungstic acid hydrate, 1.2-1.8% (w/v) zinc acetate dihydrate, 13.0-19.0% (v/v) acetic acid, with the remainder being water.