EFFICIENCY OF DIFFERENT BIOINFORMATICS TOOLS IN METABOLITE PROFILING OF WHOLE COW’S MILK USING SYNTHETICALLY WATER-REMOVED 1H NMR SPECTRA: A COMPARATIVE STUDY

Nora Laref

doi:10.15414/jmbfs.2020.10.2.241-244

Abstract

Large water peak obscures the signals corresponding to important metabolites, and thus hinders in obtaining complete information from samples. This study investigates the efficiency of three bioinformatics tools (Galaxy, Chenomx, and MetaboHunter) on the synthetically water-removed NMR spectra of whole cow’s milk and compares the results obtained. Three samples of whole cow’s milk were collected from Oran region (Algeria) and kept at –18 ºC until analysis. 1H NMR spectra of the samples in DMSO d6 were recorded at ambient temperature without any pretreatment or purification, and the spectra were first processed with MestreNova to remove water and solvent artificially, followed by metabolite profiling using the above mentioned three bioinformatics tools. Detection of several metabolites, such as taurine, glycine, choline, threitol, niacinamide, and 1,3- dimethylurate, etc., was possible using the bioinformatics tools post water and solvent removal. In addition, dry content matter estimation revealed M3 as the richest milk among the three test samples. Although the bioinformatics tools identified many milk metabolites, there are differences in the detection efficiency probably because of the separate algorithm and different file format used by them.

Highlights

IntroductionAn exceptionally complex biological fluid of either human or bovine origin, contains mostly water, carbohydrates (mainly lactose), fat, proteins (casein micelles), minerals and vitamins
Milk, an exceptionally complex biological fluid of either human or bovine origin, contains mostly water, carbohydrates, fat, proteins, minerals and vitamins
Since milk originate from different cell types and metabolisms in the organism, the profiling of milk metabolites has often been carried out using high-throughput metabolomics methodologies such as high-resolution proton nuclear magnetic resonance (1H NMR) spectroscopy, liquid chromatography mass spectrometry (LC-MS), and gas chromatography mass spectrometry (GC-MS)

Summary

Introduction

An exceptionally complex biological fluid of either human or bovine origin, contains mostly water, carbohydrates (mainly lactose), fat, proteins (casein micelles), minerals and vitamins. Many reports are available in literature, on the analysis of milk metabolites using NMR spectroscopy since it allows easy sample handling and simultaneously detects a large number of compounds with a minimal amount of sample (Belloque, 1999 ; Lamanna et al, 2011 ; Santos et al, 2016). Since milk constitutes of large amount of water, without water suppression/removal, it is difficult to detect other signals characteristics to important metabolites present in milk To avoid this issue, 13C or 15P NMR spectroscopy has usually been used to analyze milk; these require pretreatment of milk samples. Pretreatment may result in structural changes in milk components In this scenario, liquid-state 1H NMR is a more nondestructive technique despite the issue of huge water peak obscuring signals characteristics to important milk metabolites. Bioinformatics tools such as Metabohunter, Chenomx, and Galaxy, etc. rely both on efficient water suppression

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Conclusion