scholarly journals Network Analysis Based on Unique Spectral Features Enables an Efficient Selection of Genomically Diverse Operational Isolation Units

2021 ◽  
Vol 9 (2) ◽  
pp. 416
Author(s):  
Charles Dumolin ◽  
Charlotte Peeters ◽  
Evelien De Canck ◽  
Nico Boon ◽  
Peter Vandamme

Culturomics-based bacterial diversity studies benefit from the implementation of MALDI-TOF MS to remove genomically redundant isolates from isolate collections. We previously introduced SPeDE, a novel tool designed to dereplicate spectral datasets at an infraspecific level into operational isolation units (OIUs) based on unique spectral features. However, biological and technical variation may result in methodology-induced differences in MALDI-TOF mass spectra and hence provoke the detection of genomically redundant OIUs. In the present study, we used three datasets to analyze to which extent hierarchical clustering and network analysis allowed to eliminate redundant OIUs obtained through biological and technical sample variation and to describe the diversity within a set of spectra obtained from 134 unknown soil isolates. Overall, network analysis based on unique spectral features in MALDI-TOF mass spectra enabled a superior selection of genomically diverse OIUs compared to hierarchical clustering analysis and provided a better understanding of the inter-OIU relationships.

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Sivkheng Kann ◽  
Sena Sao ◽  
Chanleakhena Phoeung ◽  
Youlet By ◽  
Juliet Bryant ◽  
...  

Abstract Background Serotyping of Streptococcus pneumoniae is important for monitoring of vaccine impact. Unfortunately, conventional and molecular serotyping is expensive and technically demanding. This study aimed to determine the ability of matrix-assisted laser desorption-ionisation time-of-flight (MALDI-TOF) mass spectrometry to discriminate between pneumococcal serotypes and genotypes (defined by global pneumococcal sequence cluster, GPSC). In this study, MALDI-TOF mass spectra were generated for a diverse panel of whole genome sequenced pneumococcal isolates using the bioMerieux VITEK MS in clinical diagnostic (IVD) mode. Discriminatory mass peaks were identified and hierarchical clustering was performed to visually assess discriminatory ability. Random forest and classification and regression tree (CART) algorithms were used to formally determine how well serotypes and genotypes were identified by MALDI-TOF mass spectrum. Results One hundred and ninety-nine pneumococci, comprising 16 serotypes and non-typeable isolates from 46 GPSC, were analysed. In the primary experiment, hierarchical clustering revealed poor congruence between MALDI-TOF mass spectrum and serotype. The correct serotype was identified from MALDI-TOF mass spectrum in just 14.6% (random forest) or 35.4% (CART) of 130 isolates. Restricting the dataset to the nine dominant GPSC (61 isolates / 13 serotypes), discriminatory ability improved slightly: the correct serotype was identified in 21.3% (random forest) and 41.0% (CART). Finally, analysis of 69 isolates of three dominant serotype-genotype pairs (6B-GPSC1, 19F-GPSC23, 23F-GPSC624) resulted in the correct serotype identification in 81.1% (random forest) and 94.2% (CART) of isolates. Conclusions This work suggests that MALDI-TOF is not a useful technique for determination of pneumococcal serotype. MALDI-TOF mass spectra appear more associated with isolate genotype, which may still have utility for future pneumococcal surveillance activities.


2017 ◽  
Vol 53 (2) ◽  
pp. 162-171 ◽  
Author(s):  
Andrea R. Kelley ◽  
Madeline E. Colley ◽  
George Perry ◽  
Stephan B.H. Bach

2007 ◽  
Vol 79 (4) ◽  
pp. 1639-1645 ◽  
Author(s):  
Alena Krupková ◽  
Jan Čermák ◽  
Zuzana Walterová ◽  
Jiří Horský

1999 ◽  
Vol 71 (15) ◽  
pp. 3226-3230 ◽  
Author(s):  
Ricky D. Holland ◽  
Christopher R. Duffy ◽  
Fatemeh Rafii ◽  
John B. Sutherland ◽  
Thomas M. Heinze ◽  
...  

2007 ◽  
Vol 24 (1) ◽  
pp. 63-70 ◽  
Author(s):  
D. Mantini ◽  
F. Petrucci ◽  
P. Del Boccio ◽  
D. Pieragostino ◽  
M. Di Nicola ◽  
...  

2011 ◽  
Vol 76 (12) ◽  
pp. 1687-1701 ◽  
Author(s):  
Bojana Damnjanovic ◽  
Biljana Petrovic ◽  
Jasmina Dimitric-Markovic ◽  
Marijana Petkovic

In this work, the matrix-assisted laser desorption and ionization time-of-flight (MALDI-TOF) mass spectra of two cationic complexes, i.e., [PdCl(dien)]Cl and [Ru(en)2Cl2]Cl, acquired under different conditions were analyzed. The spectra were recorded with three matrices with or without trifluoroacetic acid (TFA), i.e., two traditional matrices, i.e., 2,5-dihydroxybenzoic acid and ?-cyano-hydroxycinnamic acid, and one flavonoid, quercetin. The spectra acquired with quercetin appeared to be the simplest, whereas in the spectra obtained with other matrices, peaks arising either from the addition of matrix molecules or from the fragmentation products were detectable. Addition of TFA did not complicate the spectra of the Pd(II) and Ru(III) complexes when the traditional matrices were used. On the other hand, the spectra of Pd complex were simpler, whereas the addition of TFA in the case of the Ru complex resulted in a higher number of peaks, some of which could not be identified. Taken together, the results of this study once more emphasize the differences arising in the MALDI-TOF mass spectra of transition metal complexes in dependence on the applied matrix.


Analusis ◽  
1998 ◽  
Vol 26 (10) ◽  
pp. 36-36 ◽  
Author(s):  
D. Suckau ◽  
L. Cornett ◽  
K. O. Kräuter

2017 ◽  
Author(s):  
Eugenio Del Prete ◽  
Angelo Facchiano ◽  
Aldo Profumo ◽  
Claudia Angelini ◽  
Paolo Romano

Introduction Computational reproducibility refers to the possibility of reconstructing all the steps of a workflow that connects raw data, processed data and results: it is a fundamental issue in the omic studies because of the complex and high-dimensional nature of the involved data. The analysis of omics data needs to exploit multi-step workflows including pre-processing, elaboration, statistical validation, interpretation and presentation. Although some analysis platforms are able to ensure computational reproducibility for different omics studies, they do not provide explicit information about the executed code. The availability of the code increases the quality of research in terms of transparency and knowledge transfer. Moreover, it allows other researchers to reproduce the results in a local system, make a comparison among the results and re-use computer code for analyzing different dataset. Methods Geena 2 is a robust web tool for MALDI-ToF mass spectra pre-processing. Its main output is the list of common peaks identified by aligning average spectra originated from groups of replicates from different samples. Intermediate results are also made available. GeenaR is an extension of Geena 2 still under development. Its objective is the integration in the platform of some R libraries, which may provide advanced statistical analyses, thus enriching the current output. It is noteworthy that many R packages follow the reproducible research philosophy.For the aims of GeenaR, the following R packages and tools have been considered: R-Markdown, knitr and spin. The implementation of these resources on an existing web platform can be an added value for its reporting features, since it improves the creation of a report about the work carried out, especially with reference to the code. Results and Discussion One of the aims of both Geena 2 and GeenaR is facilitating the users in analyzing MALDI-ToF mass spectra by providing a web-interface that allows to upload data, select different algorithms and parameters, execute the analysis in order to obtain results according to a specific demand. Thanks to the novel reproducible research module implemented in GeenaR, the system generates a report containing all the steps performed. More in details, the report will provide: date and time of the execution, the R libraries used for the process, chunks of code for main elaborations, selected parameters (either by the users or by the system), uploaded data in MALDIquant ‘Mass Spectrum’ class type, numerical and graphical results, short explanation about the workflow, version of the system and of the packages. GeenaR generates the results in a compressed archive, with separated log and graphical results, and a report, both in R-Markdown and in HTML format. It is important to underline strongly that reproducible research is not an optional, but a fundamental component of a good computational practice, which becomes essential in computational biology.


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