Multi-stage search for microbial mass spectra libraries
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Solution Overview
Problem
Current methods for identifying microbes using mass spectrometry face challenges in speed and efficiency, particularly as the size of reference libraries grows, leading to increased computation times that are not compatible with rapid sample acquisition rates.
Innovation Solution
Implementing a multi-stage search strategy that divides the reference library into hierarchically organized sub-libraries based on the statistical prevalence of microbes, allowing for a focused initial search in a small sub-library and subsequent searches in higher stages only if necessary, thereby minimizing identification time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reference library size is increased to improve identification accuracy, then the completeness of microbe coverage is improved, but the computation time increases
Solution Approach 1:
The reference library is divided into multiple sub-libraries organized in a hierarchical structure with different stages. Each sub-library contains reference spectra for specific groups of microbes (e.g., by genus, family, or statistical frequency). The search process segments the comparison into multiple passes, first searching smaller sub-libraries and progressively moving to larger ones only if needed, thereby reducing the average computation time while maintaining complete coverage for accurate identification.
2Adaptability or versatility
If the reference library size is increased to improve identification accuracy, then the coverage of microbe species is improved, but the processing speed deteriorates
Solution Approach 1:
The reference library is pre-organized into a hierarchical structure with multiple stages before the actual identification process begins. Sub-libraries are prepared in advance with reference spectra grouped by taxonomic categories or statistical frequency. During identification, the system performs preliminary searches in smaller, pre-defined sub-libraries first, and only expands to larger sub-libraries if the initial search fails to produce a confident match, thereby maintaining high processing speed while preserving comprehensive species coverage.
3Reliability
If a complete library search is performed to ensure accurate identification, then the identification reliability is improved, but the identification time increases
Solution Approach 1:
The identification process is segmented into multiple passes through hierarchical sub-libraries. The first pass searches a small sub-library containing reference spectra for frequently encountered microbes or specific taxonomic groups. If no confident match is found (below a threshold similarity score), the search automatically proceeds to subsequent passes with progressively larger sub-libraries. This segmentation ensures that most identifications are completed quickly in the first pass, while maintaining the option to search the complete library for difficult cases, thereby balancing reliability with reduced average identification time.
Data Source
AI summary
Microbes in a sample are identified by calculating similarities between a mass spectrum of the sample and reference mass spectra in a spectral library. The spectral library is divided into a hierarchy of sub-libraries where each sub-library contains reference mass spectra of microbes which are statistically the most prevalent in the samples, but are not included in other sub-libraries and all additional reference mass spectra in the library that have substantial similarity to the reference mass spectra of these microbes. Only if the search in a sub-library does not provide a hit with sufficient certainty of identification, is the search carried out in sub-libraries of higher stages.