Dual Membrane Filtration for Microbial Sample Preparation
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Solution Overview
Problem
Conventional methods for microbiological analysis of liquids containing multiple types of microorganisms, such as those in the manufacturing chain for monoclonal antibodies, face challenges like false negatives and false positives due to the presence of eukaryote cells, which can interfere with detection methods by releasing toxins or perturbing results.
Innovation Solution
A method involving a tubular body with two membranes of different pore diameters is used to select microorganisms based on size, where the liquid passes through a first membrane retaining larger eukaryote cells and then through a second membrane with smaller pores to collect desired microorganisms, such as bacteria and viruses, on the second membrane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional detection on gel growth medium is used, then microbiological analysis can be performed, but false negatives occur due to toxins released by eukaryote cells
Solution Approach 1:
The patent extracts and removes eukaryote cells from the liquid sample before microbiological analysis. This is achieved by adding a lysing agent that specifically lyses eukaryote cells, followed by filtration to remove the lysed cell debris and intact eukaryote cells. The result is a clarified sample containing only bacteria and viruses, eliminating the harmful interference from eukaryote cells while preserving the target microorganisms for accurate detection.
Solution Approach 2:
The patent performs preliminary lysis of eukaryote cells before the actual microbiological detection step. By adding the lysing agent and performing filtration in advance, the harmful eukaryote cells are eliminated before they can interfere with the detection process. This preliminary action ensures that subsequent detection methods operate on a clean sample without interference from eukaryote-derived toxins or cellular debris.
2Reliability
If chemical lysis is used for selection, then eukaryote cells can be removed, but a small proportion of desired microorganisms undergo lysis causing false negatives
Solution Approach 1:
The patent employs a filtration membrane with specific pore size as the selection mechanism instead of chemical lysis. The membrane pores are sized to allow passage of bacteria and viruses while retaining eukaryote cells and their debris. This physical separation method based on size exclusion eliminates the need for chemical lysis, thereby preventing unintended lysis of target microorganisms while achieving effective separation and high recovery of desired bacteria and viruses.
3Reliability
If centrifuging at low speed is used to separate microorganisms, then separation by mass can be achieved, but the process is more complex and less precise than filtration by size
Solution Approach 1:
The patent replaces the mechanical centrifugation system with a simpler filtration system based on size exclusion. Instead of using centrifugal force to separate microorganisms by mass, the invention uses a filtration membrane with predetermined pore sizes that automatically separates microorganisms by their physical size. This substitution of the separation mechanism simplifies the device structure, eliminates the need for complex centrifugation equipment, and provides more precise separation based on the inherent size differences between eukaryote cells and target microorganisms.
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 effectively separates microorganisms by size, reducing marginal errors and providing a simpler, more reliable sample preparation for analysis, improving detection accuracy and convenience compared to existing methods.
Implementation Method 1
passing a predetermined volume of said liquid from the first to the second compartment through said first membrane
Implementation Method 2
passing all the filtrate, having so reached the second compartment, from the second to the third compartment through said second membrane in order to collect said sample on said second membrane
Data Source
AI summary
The preparation unit comprises a body (2) within which are fixed a first (3) and a second (4) membrane, said first membrane (3) having a first predetermined pore diameter and said second membrane (4) a second predetermined pore diameter smaller than said first predetermined pore diameter of said first membrane (3), said body also comprising means (16, 20) for retrieving said sample collected on said second membrane (4).The method of preparing such a sample comprises the step of procuring such a preparation unit (1), the step of passing a predetermined volume of said liquid through said first membrane and through said second membrane (4) in order to collect a sample on said second membrane (4); and the step of retrieving said sample so collected on said second membrane (4).