title: Identification of specific metabolites in culture supernatant of Mycobacterium tuberculosis using metabolomics: exploration of potential biomarkers.
abstract: Although previous studies have reported the use of metabolomics for Mycobacterium species differentiation, little is known about the potential of extracellular metabolites of Mycobacterium tuberculosis (MTB) as specific biomarkers. Using an optimized ultrahigh performance liquid chromatography-electrospray ionization-quadruple time of flight-mass spectrometry (UHPLC-ESI-Q-TOF-MS) platform, we characterized the extracellular metabolomes of culture supernatant of nine MTB strains and nine non-tuberculous Mycobacterium (NTM) strains (four M. avium complex, one M. bovis Bacillus Calmette-Guérin (BCG), one M. chelonae, one M. fortuitum and two M. kansasii). Principal component analysis readily distinguished the metabolomes between MTB and NTM. Using multivariate and univariate analysis, 24 metabolites with significantly higher levels in MTB were identified. While seven metabolites were identified by tandem mass spectrometry (MS/MS), the other 17 metabolites were unidentified by MS/MS against database matching, suggesting that they may be potentially novel compounds. One metabolite was identified as dexpanthenol, the alcohol analog of pantothenic acid (vitamin B5), which was not known to be produced by bacteria previously. Four metabolites were identified as 1-tuberculosinyladenosine (1-TbAd), a product of the virulence-associated enzyme Rv3378c, and three previously undescribed derivatives of 1-TbAd. Two derivatives differ from 1-TbAd by the ribose group of the nucleoside while the other likely differs by the base. The remaining two metabolites were identified as a tetrapeptide, Val-His-Glu-His, and a monoacylglycerophosphoglycerol, phosphatidylglycerol (PG) (16∶0/0∶0), respectively. Further studies on the chemical structure and biosynthetic pathway of these MTB-specific metabolites would help understand their biological functions. Studies on clinical samples from tuberculosis patients are required to explore for their potential role as diagnostic biomarkers.
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases , Hong Kong, China ; Research Centre of Infection and Immunology, The University of Hong Kong , Hong Kong, China ; Carol Yu Centre for Infection, The University of Hong Kong , Hong Kong, China ; Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Susanna K P
authors.initials: SK
authors.lastname: Lau
authors.affiliation: Department of Pathology, The University of Hong Kong , Hong Kong, China.
authors.forename: Ching-Wan
authors.initials: CW
authors.lastname: Lam
authors.affiliation: Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Shirly O T
authors.initials: SO
authors.lastname: Curreem
authors.affiliation: Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Kim-Chung
authors.initials: KC
authors.lastname: Lee
authors.affiliation: Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Candy C Y
authors.initials: CC
authors.lastname: Lau
authors.affiliation: Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Wang-Ngai
authors.initials: WN
authors.lastname: Chow
authors.affiliation: Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Antonio H Y
authors.initials: AH
authors.lastname: Ngan
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases , Hong Kong, China ; Research Centre of Infection and Immunology, The University of Hong Kong , Hong Kong, China ; Carol Yu Centre for Infection, The University of Hong Kong , Hong Kong, China ; Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Kelvin K W
authors.initials: KK
authors.lastname: To
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases , Hong Kong, China ; Research Centre of Infection and Immunology, The University of Hong Kong , Hong Kong, China ; Carol Yu Centre for Infection, The University of Hong Kong , Hong Kong, China ; Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Jasper F W
authors.initials: JF
authors.lastname: Chan
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases , Hong Kong, China ; Research Centre of Infection and Immunology, The University of Hong Kong , Hong Kong, China ; Carol Yu Centre for Infection, The University of Hong Kong , Hong Kong, China ; Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Ivan F N
authors.initials: IF
authors.lastname: Hung
authors.affiliation: Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Wing-Cheong
authors.initials: WC
authors.lastname: Yam
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases , Hong Kong, China ; Research Centre of Infection and Immunology, The University of Hong Kong , Hong Kong, China ; Carol Yu Centre for Infection, The University of Hong Kong , Hong Kong, China ; Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Kwok-Yung
authors.initials: KY
authors.lastname: Yuen
authors.affiliation: State Key Laboratory of Emerging Infectious Diseases , Hong Kong, China ; Research Centre of Infection and Immunology, The University of Hong Kong , Hong Kong, China ; Carol Yu Centre for Infection, The University of Hong Kong , Hong Kong, China ; Department of Microbiology, The University of Hong Kong , Hong Kong, China.
authors.forename: Patrick C Y
authors.initials: PC
authors.lastname: Woo
mesh_terms: D015415:Biomarkers / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D008055:Lipids / Q000032:analysis; D055432:Metabolomics; D009169:Mycobacterium tuberculosis / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D009170:Nontuberculous Mycobacteria / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism; D010205:Pantothenic Acid / Q000031:analogs & derivatives / Q000032:analysis; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: C587948:1-tuberculosinyladenosine; D015415:Biomarkers; D008055:Lipids; D010205:Pantothenic Acid; C007288:dexpanthenol
keywords: Mycobacterium tuberculosis; biomarkers; diagnosis; metabolomics; specific