Microorganism Discrimination Using Wavelet-Masked Mass Spectra

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Solution Overview

Problem

Conventional MALDI-MS methods face challenges in accurately discriminating between closely related microorganisms, such as subspecies, strains, or types, requiring the analysis of numerous biomarker peaks.

Innovation Solution

A method and system that acquire mass spectra from known microorganisms, create a mask based on marker-candidate protein m/z values, perform continuous wavelet transforms, and use machine learning to create a discriminant model for accurate discrimination of unknown microorganisms by transforming their mass spectra into wavelet images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional MALDI-MS methods are used to discriminate closely related microorganisms, then discrimination can be performed, but a considerable number of biomarker peaks must be checked, reducing efficiency

Engineering Contradiction:
Improvediscrimination accuracyVSAvoiddiscrimination efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent extracts only the essential biomarker peaks that are actually useful for discrimination from the complete mass spectrum. By identifying and isolating these key peaks through the proposed method, the system eliminates the need to analyze all peaks, thereby maintaining high discrimination accuracy while significantly improving processing efficiency.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies local quality by assigning different importance weights to different regions of the mass spectrum. Instead of treating all peaks equally, the method identifies specific local regions containing biomarker peaks and focuses analysis there, allowing efficient discrimination with fewer peaks while maintaining accuracy.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If more biomarker peaks are checked to improve discrimination accuracy, then discrimination precision improves, but the complexity and time required increases

Engineering Contradiction:
Improvediscrimination precisionVSAvoidanalysis time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary action by pre-identifying and marking the positions of biomarker peaks before the actual discrimination analysis. This preliminary step allows the system to quickly locate and focus only on relevant peaks during analysis, reducing the time required while maintaining high precision discrimination.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent applies partial action by analyzing only the necessary subset of biomarker peaks rather than all possible peaks. This selective approach achieves sufficient discrimination precision with reduced analysis time, avoiding the excessive action of checking every possible peak.

Inventive Principle:
Principle #16Partial or excessive action

3Ease of operation

If traditional peak comparison methods are used, then the process is straightforward, but discrimination accuracy for closely related microorganisms is insufficient

Engineering Contradiction:
Improvemethod simplicityVSAvoiddiscrimination accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent changes the parameters used for discrimination by introducing a scoring system that evaluates multiple characteristics of biomarker peaks (such as position, intensity, and pattern). This parameter transformation allows the method to maintain simplicity while achieving high discrimination accuracy for closely related microorganisms that traditional methods cannot distinguish.

Inventive Principle:
Principle #35Parameter changes

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 approach enables highly accurate and efficient discrimination of microorganisms by enhancing the visibility of differences between subspecies, strains, or types, allowing for improved classification capabilities using high-performance machine-learning algorithms.

Implementation Method 1

matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS)

Methodology Applied
Scientific EffectIonization: Ionisation

Implementation Method 2

matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS)

Methodology Applied
Scientific EffectLaser desorption: Laser Ablation

Data Source

PatentUS20230282310A1Microorganism Discrimination Method and System
Publication Date: 2023.09.07 SHIMADZU CORP
  • US20230282310A1 patent drawing
  • US20230282310A1 patent drawing
  • US20230282310A1 patent drawing

AI summary

To enable a correct and easy discrimination of microorganisms, a microorganism discrimination method includes: acquiring mass spectra related to known microorganisms which belong to the same species and whose subspecies, strains or types are known (S11); retrieving a list describing m/z values of marker-candidate proteins which are supposed to vary in mass among different subspecies, strains or types (S12); creating a mask which gives non-zero values only within a predetermined range including each of the listed m/z values (S14); masking each of the mass spectra (S15); creating wavelet images by performing continuous wavelet transform on the mass spectra (S16); creating a discriminant model by machine learning using, as training data, the wavelet images and information of the subspecies, strains or types of the known microorganisms; and discriminating the subspecies, strain or type of an unknown microorganism by applying a mass spectrum of this microorganism to the discriminant model.