Alkaline DNA Capture for Difficult-to-Lyse Bacterial Samples
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Solution Overview
Problem
Existing nucleic acid isolation techniques face challenges in efficiently isolating DNA from difficult-to-lyse organisms, particularly Gram-positive bacteria, and in enhancing the detectability of nucleic acid targets in multiplex amplification reactions without compromising the detectability of other targets.
Innovation Solution
A method involving the mixing of a biological sample with an alkaline composition to create a first liquid composition, followed by the addition of a pH buffered detergent reagent to create a second liquid composition, which allows for effective cell lysis, DNA denaturation, and capture of DNA onto solid support particles, thereby isolating DNA from biological samples, including those that are difficult to lyse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nucleic acid isolation techniques are used, then the process is simple and quick, but the efficiency of lysing difficult-to-lyse organisms (such as Gram-positive bacteria) is low
Solution Approach 1:
The sample preparation process is divided into distinct sequential steps: first treating with alkaline composition to achieve cell lysis and DNA denaturation, then neutralizing with pH buffered detergent reagent to restore pH and enable DNA capture. This segmentation allows each step to optimize for its specific function, achieving reliable DNA isolation from difficult-to-lyse organisms while maintaining procedural clarity
Solution Approach 2:
The method employs dramatic pH parameter changes - first raising pH to 12.0-13.5 with alkaline composition for effective lysis of tough cell walls, then lowering to below 9.5 with pH buffered detergent reagent for DNA capture. This parameter transformation enables the system to achieve high DNA isolation efficiency from Gram-positive bacteria and other difficult-to-lyse organisms
2Reliability
If specialized techniques are used for different organisms, then the efficiency of nucleic acid isolation for each organism is improved, but the number of required techniques and reagents increases
Solution Approach 1:
The alkaline shock method using pH buffered detergent reagent serves as a universal sample preparation technique that effectively lysed multiple organism types including Gram-positive bacteria, Gram-negative bacteria, and other difficult-to-lyse organisms. This single multi-functional approach replaced the need for organism-specific techniques, maintaining high isolation efficiency across diverse samples while simplifying the overall methodology
3Productivity
If automated systems are used for sample preparation, then laboratory workflow is streamlined, but the number and type of onboard reagents become critical limitations
Solution Approach 1:
The method combines multiple functions into the pH buffered detergent reagent, which simultaneously performs pH neutralization, provides detergent for protein denaturation, and enables DNA capture. This merging reduces the number of separate reagents needed in automated systems while maintaining effective DNA isolation and supporting streamlined laboratory workflows
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 provides reliable DNA isolation results from a wide range of organisms, including Gram-positive bacteria, and significantly enhances the detectability of nucleic acid targets in amplification reactions, while maintaining the detectability of other targets in multiplex assays.
Implementation Method 1
mixing the biological sample with an alkaline composition that lyses cells and denatures DNA to create a first liquid composition, where the first liquid composition has a pH in the range of from about pH 12.0 to about pH 13.5
Implementation Method 2
mixing the first liquid composition with a pH buffered detergent reagent to create a second liquid composition having a pH lower than about pH 9.5, where the pH buffered detergent reagent includes a pH buffer, a detergent, and a solid support particle that captures DNA
Data Source
AI summary
Method of preparing a biological sample appropriate for use in a subsequent in vitro nucleic acid amplification reaction. A biological sample is combined with an alkaline composition that lyses cells and denatures DNA to create a first liquid composition. The first liquid composition is then mixed with a buffer, a detergent, and a solid support that captures DNA to create a second liquid composition. The buffer, detergent, and solid support can be delivered as components of a single reagent. Captured DNA strands can be used as templates in subsequently performed nucleic acid amplification and detection reactions with improved sensitivity.