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Beverly MB, Basile F, Voorhees KJ. Fatty Acid Analysis of Beer Spoiling Microorganisms Using Pyrolysis Mass Spectrometry. Journal of the American Society of Brewing Chemists 2018. [DOI: 10.1094/asbcj-55-0079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Michael B. Beverly
- Chemistry and Geochemistry Department, Colorado School of Mines, Golden CO 80401
| | - Franco Basile
- Chemistry and Geochemistry Department, Colorado School of Mines, Golden CO 80401
| | - Kent J. Voorhees
- Chemistry and Geochemistry Department, Colorado School of Mines, Golden CO 80401
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Saichek NR, Cox CR, Kim S, Harrington PB, Stambach NR, Voorhees KJ. Strain-level Staphylococcus differentiation by CeO2-metal oxide laser ionization mass spectrometry fatty acid profiling. BMC Microbiol 2016; 16:72. [PMID: 27107714 PMCID: PMC4842276 DOI: 10.1186/s12866-016-0658-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 03/02/2016] [Indexed: 11/10/2022] Open
Abstract
Background The Staphylococcus genus is composed of 44 species, with S. aureus being the most pathogenic. Isolates of S. aureus are generally susceptible to β-lactam antibiotics, but extensive use of this class of drugs has led to increasing emergence of resistant strains. Increased occurrence of coagulase-negative staphylococci as well as S. aureus infections, some with resistance to multiple classes of antibiotics, has driven the necessity for innovative options for treatment and infection control. Despite these increasing needs, current methods still only possess species-level capabilities and require secondary testing to determine antibiotic resistance. This study describes the use of metal oxide laser ionization mass spectrometry fatty acid (FA) profiling as a rapid, simultaneous Staphylococcus identification and antibiotic resistance determination method. Results Principal component analysis was used to classify 50 Staphyloccocus isolates. Leave-one-spectrum-out cross-validation indicated 100 % correct assignment at the species and strain level. Fuzzy rule building expert system classification and self-optimizing partial least squares discriminant analysis, with more rigorous evaluations, also consistently achieved greater than 94 and 84 % accuracy, respectively. Preliminary analysis differentiating MRSA from MSSA demonstrated the feasibility of simultaneous determination of strain identification and antibiotic resistance. Conclusion The utility of CeO2-MOLI MS FA profiling coupled with multivariate statistical analysis for performing strain-level differentiation of various Staphylococcus species proved to be a fast and reliable tool for identification. The simultaneous strain-level detection and antibiotic resistance determination achieved with this method should greatly improve outcomes and reduce clinical costs for therapeutic management and infection control.
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Affiliation(s)
- Nicholas R Saichek
- Department of Chemistry, Colorado School of Mines, Golden, CO, 80401, USA
| | - Christopher R Cox
- Department of Chemistry, Colorado School of Mines, Golden, CO, 80401, USA
| | - Seungki Kim
- Korea Institute of Science and Technology, Hwarangno 14-gil 5, Seongbuk-gu, Seoul, 136-791, Republic of Korea
| | - Peter B Harrington
- Center for Intelligent Chemical Instrumentation, Department of Chemistry, Clippinger Laboratories, Ohio University, Athens, OH, 45701, USA
| | | | - Kent J Voorhees
- Department of Chemistry, Colorado School of Mines, Golden, CO, 80401, USA.
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Stambach NR, Carr SA, Cox CR, Voorhees KJ. Rapid Detection of Listeria by Bacteriophage Amplification and SERS-Lateral Flow Immunochromatography. Viruses 2015; 7:6631-41. [PMID: 26694448 PMCID: PMC4690885 DOI: 10.3390/v7122962] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 11/02/2015] [Accepted: 12/10/2015] [Indexed: 11/16/2022] Open
Abstract
A rapid Listeria detection method was developed utilizing A511 bacteriophage amplification combined with surface-enhanced Raman spectroscopy (SERS) and lateral flow immunochromatography (LFI). Anti-A511 antibodies were covalently linked to SERS nanoparticles and printed onto nitrocellulose membranes. Antibody-conjugated SERS nanoparticles were used as quantifiable reporters. In the presence of A511, phage-SERS nanoparticle complexes were arrested and concentrated as a visible test line, which was interrogated quantitatively by Raman spectroscopy. An increase in SERS intensity correlated to an increase in captured phage-reporter complexes. SERS limit of detection was 6 × 10(6) pfu·mL(-1), offering detection below that obtainable by the naked eye (LOD 6 × 10(7) pfu·mL(-1)). Phage amplification experiments were carried out at a multiplicity of infection (MOI) of 0.1 with 4 different starting phage concentrations monitored over time using SERS-LFI and validated by spot titer assay. Detection of L. monocytogenes concentrations of 1 × 10(7) colony forming units (cfu)·mL(-1), 5 × 10(6) cfu·mL(-1), 5 × 10(5) cfu·mL(-1) and 5 × 10(4) cfu·mL(-1) was achieved in 2, 2, 6, and 8 h, respectively. Similar experiments were conducted at a constant starting phage concentration (5 × 10(5) pfu·mL(-1)) with MOIs of 1, 2.5, and 5 and were detected in 2, 4, and 5 h, respectively.
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Affiliation(s)
- Nicholas R Stambach
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA.
| | - Stephanie A Carr
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA.
| | - Christopher R Cox
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA.
| | - Kent J Voorhees
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA.
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Cody RB, McAlpin CR, Cox CR, Jensen KR, Voorhees KJ. Identification of bacteria by fatty acid profiling with direct analysis in real time mass spectrometry. Rapid Commun Mass Spectrom 2015; 29:2007-2012. [PMID: 26443400 DOI: 10.1002/rcm.7309] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Revised: 08/06/2015] [Accepted: 08/07/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE Bacterial fatty acid profiling is a well-established technique for bacterial identification. Current methods involving esterification and gas chromatography/mass spectrometry (GC/MS) or matrix-assisted laser desorption/ionization (MALDI) analysis are effective, but there are potential benefits to be gained by investigating ambient ionization methods that can provide rapid analysis without derivatization or additional sample handling. METHODS Lipid extracts from colonies of five Gram-positive and five Gram-negative pathogenic bacteria were analyzed by Direct Analysis in Real Time (DART) ionization coupled with a time-of-flight mass spectrometer. Fatty acid profiles were obtained from the negative-ion DART mass spectra without additional derivatization or sample preparation. RESULTS Fatty acid profiles obtained from the deprotonated molecules [M - H](-) were found to be highly species-specific and reproducible. Leave-one-out cross validation (LOOCV) for principal component analysis (PCA) showed 100% correct classification accuracy. CONCLUSIONS The results of this preliminary feasibility study show good precision and accuracy, and the fatty acid patterns are clearly distinctive for each of the ten species examined. The speed and ease of analysis and the high classification accuracy for this initial study indicate that DART is an effective method for bacterial fatty acid profiling.
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Affiliation(s)
- Robert B Cody
- JEOL USA, Inc., 11 Dearborn Rd., Peabody, MA, 01960, USA
| | - Casey R McAlpin
- Colorado School of Mines, 1012 14th Street, Golden, CO, 80401, USA
| | | | - Kirk R Jensen
- Colorado School of Mines, 1012 14th Street, Golden, CO, 80401, USA
| | - Kent J Voorhees
- Colorado School of Mines, 1012 14th Street, Golden, CO, 80401, USA
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Cox CR, Jensen KR, Mondesire RR, Voorhees KJ. Rapid detection of Bacillus anthracis by γ phage amplification and lateral flow immunochromatography. J Microbiol Methods 2015; 118:51-6. [PMID: 26310605 DOI: 10.1016/j.mimet.2015.08.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 08/12/2015] [Accepted: 08/13/2015] [Indexed: 11/18/2022]
Abstract
New, rapid point-of-need diagnostic methods for Bacillus anthracis detection can enhance civil and military responses to accidental or deliberate dispersal of anthrax as a biological weapon. Current laboratory-based methods for clinical identification of B. anthracis require 12 to 120h, and are confirmed by plaque assay using the well-characterized γ typing phage, which requires an additional minimum of 24h for bacterial culture. To reduce testing time, the natural specificity of γ phage amplification was investigated in combination with lateral flow immunochromatography (LFI) for rapid, point-of-need B. anthracis detection. Phage-based LFI detection of B. anthracis Sterne was validated over a range of bacterial and phage concentrations with optimal detection achieved in as little as 2h from the onset of amplification with a threshold sensitivity of 2.5×10(4)cfu/mL. The novel use of γ phage amplification detected with a simple, inexpensive LFI assay provides a rapid, sensitive, highly accurate, and field-deployable method for diagnostic ID of B. anthracis in a fraction of the time required by conventional techniques, and without the need for extensive laboratory culture.
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Affiliation(s)
- Christopher R Cox
- Colorado School of Mines, Department of Chemistry and Geochemistry, Golden, CO 80401, United States
| | - Kirk R Jensen
- Colorado School of Mines, Department of Chemistry and Geochemistry, Golden, CO 80401, United States
| | | | - Kent J Voorhees
- Colorado School of Mines, Department of Chemistry and Geochemistry, Golden, CO 80401, United States
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Cox CR, Jensen KR, Saichek NR, Voorhees KJ. Strain-level bacterial identification by CeO2-catalyzed MALDI-TOF MS fatty acid analysis and comparison to commercial protein-based methods. Sci Rep 2015; 5:10470. [PMID: 26190224 PMCID: PMC4507139 DOI: 10.1038/srep10470] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Accepted: 04/16/2015] [Indexed: 12/27/2022] Open
Abstract
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged as a rapid approach for clinical bacterial identification. However, current protein-based commercial bacterial ID methods fall short when differentiating closely related species/strains. To address this shortcoming, we employed CeO2-catalyzed fragmentation of lipids to produce fatty acids using the energy inherent to the MALDI laser as a novel alternative to protein profiling. Fatty acid profiles collected from Enterobacteriaceae, Acinetobacter, and Listeria using CeO2-catalyzed metal oxide laser ionization (MOLI MS), processed by principal component analysis, and validated by leave-one-out cross-validation (CV), showed 100% correct classification at the species level and 98% at the strain level. In comparison, protein profile data from the same bacteria yielded 32%, 54% and 67% mean species-level accuracy using two MALDI-TOF MS platforms, respectively. In addition, several pathogens were misidentified by protein profiling as non-pathogens and vice versa. These results suggest novel CeO2-catalyzed lipid fragmentation readily produced (i) taxonomically tractable fatty acid profiles by MOLI MS, (ii) highly accurate bacterial classification and (iii) consistent strain-level ID for bacteria that were routinely misidentified by protein-based methods.
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Affiliation(s)
- C R Cox
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401
| | - K R Jensen
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401
| | - N R Saichek
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401
| | - K J Voorhees
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401
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Jensen KR, Voorhees KJ. Analytical applications of electron monochromator-mass spectrometry. Mass Spectrom Rev 2015; 34:24-42. [PMID: 24272909 DOI: 10.1002/mas.21395] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 06/17/2013] [Accepted: 06/17/2013] [Indexed: 06/02/2023]
Abstract
An electron monochromator (EM) produces an electron beam with a narrow energy distribution that can be utilized with mass spectrometry (MS). The history and development of the EM from an initial research design to a commercial model are reviewed along with MS research applications. An EM incorporated with a mass spectrometer showed significant improvement in sensitivity over traditional methods for negative-ion generation and selectivity for compounds with electrophilic character. Sensitivity of EM-MS has been shown to be 25 fg for hexachlorobenzene in positive-ion mode and 10 fg for nitrobenzene in negative-ion mode. Reports regarding the analysis of chlorinated compounds, explosives, pesticides, phthalates, polychlorodibenzo-p-dioxins, polycyclic aromatic hydrocarbons (PAHs), nitro-polycyclic aromatic hydrocarbons (NPAHs), antioxidants, and bacterial biomarkers are discussed. Additionally, theoretical methods to predict electron-capture properties are presented.
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Affiliation(s)
- Kirk R Jensen
- Colorado School of Mines, Department of Chemistry and Geochemistry, 1012 14th Street #204, Golden, Colorado, 80401
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Cox CR, Saichek NR, Schweizer HP, Voorhees KJ. Rapid Burkholderia pseudomallei identification and antibiotic resistance determination by bacteriophage amplification and MALDI-TOF MS. Bacteriophage 2014; 4:e29011. [PMID: 25050191 PMCID: PMC4090906 DOI: 10.4161/bact.29011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 04/23/2014] [Accepted: 04/24/2014] [Indexed: 12/02/2022]
Abstract
Phage amplification detected by MALDI-TOF MS was investigated for rapid and simultaneous Burkholderia pseudomallei identification and ceftazidime resistance determination. B. pseudomallei ceftazidime susceptible and resistant ΔpurM mutant strains Bp82 and Bp82.3 were infected with broadly targeting B. pseudomallei phage ϕX216 and production of the m/z 37.6 kDa phage capsid protein observed by MALDI-TOF MS over the course of 3 h infections. This allowed for repoducible phage-based bacterial ID within 2 h of the onset of infection. MALDI-TOF MS-measured time to detection correlated with in silico modeling, which predicted an approximate 2 h detection time. Ceftazidime susceptible strain Bp82, while detectable in the absence of the drug, owing to the reliance of phage amplification on a viable host, was not detectable when 10 μg/mL ceftazidime was added at the onset of infection. In contrast, resistant strain Bp82.3 was detected in the same 2 h timeframe both with and without the addition of ceftazidime.
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Affiliation(s)
- Christopher R Cox
- Department of Chemistry and Geochemistry; Colorado School of Mines; Golden, CO USA
| | - Nicholas R Saichek
- Department of Chemistry and Geochemistry; Colorado School of Mines; Golden, CO USA
| | - Herbert P Schweizer
- Department of Microbiology, Immunology and Pathology; Colorado State University; IDRC at Foothills Campus; Fort Collins, CO USA
| | - Kent J Voorhees
- Department of Chemistry and Geochemistry; Colorado School of Mines; Golden, CO USA
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McAlpin CR, Voorhees KJ. Extension of metal oxide laser ionization mass spectrometry to analytes with varied chemical functionalities. Rapid Commun Mass Spectrom 2013; 27:1763-1768. [PMID: 23821569 DOI: 10.1002/rcm.6629] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 05/09/2013] [Accepted: 05/14/2013] [Indexed: 06/02/2023]
Abstract
RATIONALE Applications of metal oxide laser ionization mass spectrometry (MOLI MS) have been limited to compounds that provide protons for ionization upon adsorption to a metal oxide surface. The addition of a small molecule, which can act as a proton source and extend MOLI MS applications to a wider variety of analytes, was investigated. METHODS Mass spectrometric measurements were made with a PerSeptive Biosystems Voyager DE-STR MALDI mass spectrometer, using NiO-based MOLI to generate ions. NiO was pretreated in this study with a number of small molecules to act as proton sources during ionization. Peptides, monosaccharides, and a crude oil sample were analyzed with pretreated and untreated NiO. RESULTS Candidate small molecule proton donors were evaluated based on their effect on signal-to-noise ratio and peak intensity for tristearin. The best performing proton source was used for subsequent analyses. The analysis of monosaccharides, peptides and compounds in heavy crude oil was enhanced by the use of proton source treated NiO for MOLI MS. Proton/cation exchange following ionization was observed. CONCLUSIONS Addition of a proton source to NiO enhanced the MOLI MS response for peptides, carbohydrates, and compounds in a crude oil sample. Efficient ionization of these samples effectively extended applications of MOLI MS beyond lipid analytes containing esters.
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Affiliation(s)
- Casey R McAlpin
- Department of Chemistry, 1500 Illinois, Colorado School of Mines, Golden, CO 80401, USA
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Voorhees KJ, Jensen KR, McAlpin CR, Rees JC, Cody R, Ubukata M, Cox CR. Modified MALDI MS fatty acid profiling for bacterial identification. J Mass Spectrom 2013; 48:850-855. [PMID: 23832941 DOI: 10.1002/jms.3215] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 03/27/2013] [Accepted: 03/27/2013] [Indexed: 06/02/2023]
Abstract
Bacterial fatty acid profiling is a well-established technique for bacterial identification. Ten bacteria were analyzed using both positive- and negative-ion modes with a modified matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) approach using CaO as a matrix replacement (metal oxide laser ionization MS (MOLI MS)). The results show that reproducible lipid cleavage similar to thermal in situ tetramethyl ammonium hydroxide saponification/derivatization had occurred. Principal component analysis showed that replicates from each organism grouped in a unique space. Cross validation (CV) of spectra from both ionization modes resulted in greater than 94% validation of the data. When CV results were compared for the two ionization modes, negative-ion data produced a superior outcome. MOLI MS provides clinicians a rapid, reproducible and cost-effective bacterial diagnostic tool.
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Affiliation(s)
- Kent J Voorhees
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA.
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Kvitko BH, Cox CR, DeShazer D, Johnson SL, Voorhees KJ, Schweizer HP. φX216, a P2-like bacteriophage with broad Burkholderia pseudomallei and B. mallei strain infectivity. BMC Microbiol 2012; 12:289. [PMID: 23217012 PMCID: PMC3548686 DOI: 10.1186/1471-2180-12-289] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 11/28/2012] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Burkholderia pseudomallei and B. mallei are closely related Category B Select Agents of bioterrorism and the causative agents of the diseases melioidosis and glanders, respectively. Rapid phage-based diagnostic tools would greatly benefit early recognition and treatment of these diseases. There is extensive strain-to-strain variation in B. pseudomallei genome content due in part to the presence or absence of integrated prophages. Several phages have previously been isolated from B. pseudomallei lysogens, for example φK96243, φ1026b and φ52237. RESULTS We have isolated a P2-like bacteriophage, φX216, which infects 78% of all B. pseudomallei strains tested. φX216 also infects B. mallei, but not other Burkholderia species, including the closely related B. thailandensis and B. oklahomensis. The nature of the φX216 host receptor remains unclear but evidence indicates that in B. mallei φX216 uses lipopolysaccharide O-antigen but a different receptor in B. pseudomallei. The 37,637 bp genome of φX216 encodes 47 predicted open reading frames and shares 99.8% pairwise identity and an identical strain host range with bacteriophage φ52237. Closely related P2-like prophages appear to be widely distributed among B. pseudomallei strains but both φX216 and φ52237 readily infect prophage carrying strains. CONCLUSIONS The broad strain infectivity and high specificity for B. pseudomallei and B. mallei indicate that φX216 will provide a good platform for the development of phage-based diagnostics for these bacteria.
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Affiliation(s)
- Brian H Kvitko
- Department of Microbiology, Colorado State University, IDRC at Foothills Campus, Fort Collins, CO 80523-0922, USA
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Cox CR, Rees JC, Voorhees KJ. Modeling bacteriophage amplification as a predictive tool for optimized MALDI-TOF MS-based bacterial detection. J Mass Spectrom 2012; 47:1435-1441. [PMID: 23147819 DOI: 10.1002/jms.3087] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a valuable tool for rapid bacterial detection and identification but is limited by the need for relatively high cell count samples, which have been grown under strictly controlled conditions. These requirements can be eliminated by the natural infection of a viable bacterial species of interest with a host-specific phage. This produces a rapid increase in phage protein concentrations in comparison to bacterial concentrations, which can in turn be exploited as a method for signal amplification during MALDI-TOF MS. One drawback to this approach is the requirement for repetitive, time-consuming sample preparation and analysis applied over the course of a phage infection to monitor phage concentrations as a function of time to determine the MALDI-TOF MS detection limit. To reduce the requirement for repeated preparation and analysis, a modified phage therapy model was investigated as a means for predicting the time during a given phage infection when a detectable signal would occur. The modified model used a series of three differential equations composed of predetermined experimental parameters including phage burst size and burst time to predict progeny phage concentrations as a function of time. Using Yersinia pestis with plague diagnostic phage φA1122 and Escherichia coli with phage MS2 as two separate, well-characterized model phage-host pairs, we conducted in silico modeling of the infection process and compared it with experimental infections monitored in real time by MALDI-TOF MS. Significant agreement between mathematically calculated phage growth curves and those experimentally obtained by MALDI-TOF MS was observed, thus verifying this method's utility for significant time and labor reduction.
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Affiliation(s)
- Christopher R Cox
- Colorado School of Mines, Department of Chemistry and Geochemistry, Golden, CO 80401, USA
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Affiliation(s)
- Casey R. McAlpin
- Department of Chemistry
and Geochemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Kent J. Voorhees
- Department of Chemistry
and Geochemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - April R. Corpuz
- Department of Chemistry
and Geochemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Ryan M. Richards
- Department of Chemistry
and Geochemistry, Colorado School of Mines, Golden, Colorado 80401, United States
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Ratcliff MA, Dane AJ, Williams A, Ireland J, Luecke J, McCormick RL, Voorhees KJ. Diesel particle filter and fuel effects on heavy-duty diesel engine emissions. Environ Sci Technol 2010; 44:8343-9. [PMID: 20886845 DOI: 10.1021/es1008032] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The impacts of biodiesel and a continuously regenerated (catalyzed) diesel particle filter (DPF) on the emissions of volatile unburned hydrocarbons, carbonyls, and particle associated polycyclic aromatic hydrocarbons (PAH) and nitro-PAH, were investigated. Experiments were conducted on a 5.9 L Cummins ISB, heavy-duty diesel engine using certification ultra-low-sulfur diesel (ULSD, S ≤ 15 ppm), soy biodiesel (B100), and a 20% blend thereof (B20). Against the ULSD baseline, B20 and B100 reduced engine-out emissions of measured unburned volatile hydrocarbons and PM associated PAH and nitro-PAH by significant percentages (40% or more for B20 and higher percentage for B100). However, emissions of benzene were unaffected by the presence of biodiesel and emissions of naphthalene actually increased for B100. This suggests that the unsaturated FAME in soy-biodiesel can react to form aromatic rings in the diesel combustion environment. Methyl acrylate and methyl 3-butanoate were observed as significant species in the exhaust for B20 and B100 and may serve as markers of the presence of biodiesel in the fuel. The DPF was highly effective at converting gaseous hydrocarbons and PM associated PAH and total nitro-PAH. However, conversion of 1-nitropyrene by the DPF was less than 50% for all fuels. Blending of biodiesel caused a slight reduction in engine-out emissions of acrolein, but otherwise had little effect on carbonyl emissions. The DPF was highly effective for conversion of carbonyls, with the exception of formaldehyde. Formaldehyde emissions were increased by the DPF for ULSD and B20.
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Affiliation(s)
- Matthew A Ratcliff
- National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado, USA.
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McAlpin CR, Cox CR, Matyi SA, Voorhees KJ. Enhanced matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis of bacteriophage major capsid proteins with beta-mercaptoethanol pretreatment. Rapid Commun Mass Spectrom 2010; 24:11-14. [PMID: 19967739 DOI: 10.1002/rcm.4349] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Bacteriophage (phage) proteins have been analyzed previously with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). However, analysis of phage major capsid proteins (MCPs) has been limited by the ability to reproducibly generate ions from MCP monomers. While the acidic conditions of MALDI-TOF MS sample preparation have been shown to aid in disassembly of some phage capsids, many require further treatment to successfully liberate MCP monomers. The findings presented here suggest that beta-mercaptoethanol reduction of the disulfide bonds linking phage MCPs prior to mass spectrometric analysis results in significantly increased MALDI-TOF MS sensitivity and reproducibility of Yersinia pestis-specific phage protein profiles.
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Affiliation(s)
- Casey R McAlpin
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA
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Havey CD, McCormick RL, Hayes RR, Dane AJ, Voorhees KJ. Analysis of nitro-polycyclic aromatic hydrocarbons in conventional diesel and Fischer-Tropsch diesel fuel emissions using electron monochromator-mass spectrometry. Anal Chem 2007; 78:4894-900. [PMID: 16841908 DOI: 10.1021/ac060400q] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The presence of nitro-polycyclic aromatic hydrocarbons (NPAHs) in diesel fuel emissions has been studied for a number of years predominantly because of their contribution to the overall health and environmental risks associated with these emissions. Electron monochromator-mass spectrometry (EM-MS) is a highly selective and sensitive method for detection of NPAHs in complex matrixes, such as diesel emissions. Here, EM-MS was used to compare the levels of NPAHs in fuel emissions from conventional (petroleum) diesel, ultra-low sulfur/low-aromatic content diesel, Fischer-Tropsch synthetic diesel, and conventional diesel/synthetic diesel blend. The largest quantities of NPAHs were detected in the conventional diesel fuel emissions, while the ultra-low sulfur diesel and synthetic diesel fuel demonstrated a more than 50% reduction of NPAH quantities when compared to the conventional diesel fuel emissions. The emissions from the blend of conventional diesel with 30% synthetic diesel fuel also demonstrated a more than 30% reduction of the NPAH content when compared to the conventional diesel fuel emissions. In addition, a correlation was made between the aromatic content of the different fuel types and NPAH quantities and between the nitrogen oxides emissions from the different fuel types and NPAH quantities. The EM-MS system demonstrated high selectivity and sensitivity for detection of the NPAHs in the emissions with minimal sample cleanup required.
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Affiliation(s)
- Crystal D Havey
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, Colorado 80401, USA
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Reiman RW, Atchley DH, Voorhees KJ. Indirect detection of Bacillus anthracis using real-time PCR to detect amplified gamma phage DNA. J Microbiol Methods 2007; 68:651-3. [PMID: 17208322 DOI: 10.1016/j.mimet.2006.11.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 11/03/2006] [Accepted: 11/09/2006] [Indexed: 11/20/2022]
Abstract
Typical real-time PCR methods used to identify Bacillus anthracis do not distinguish between viable and non-viable spores, which would be critical in any first response and remediation scenarios. This study combined both real-time PCR, using primers specifically designed for gamma phage, with the highly specific gamma phage amplification into one simple assay to indirectly detect Bacillus anthracis. Since the amplification of gamma phage only occurs in the presence of a suitable host, the detection of increasing concentrations of progeny gamma phage DNA using real-time PCR implies the presence of viable Bacillus anthracis cells. This method detected a starting Bacillus anthracis concentration of 207 cfu/mL, equivalent to less than one cell in 20 microL, in less than 5 h.
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Affiliation(s)
- Robert W Reiman
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO, USA.
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Dane AJ, Havey CD, Voorhees KJ. The Detection of Nitro Pesticides in Mainstream and Sidestream Cigarette Smoke Using Electron Monochromator-Mass Spectrometry. Anal Chem 2006. [DOI: 10.1021/ac061309p] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Dane AJ, Havey CD, Voorhees KJ. The detection of nitro pesticides in mainstream and sidestream cigarette smoke using electron monochromator-mass spectrometry. Anal Chem 2006; 78:3227-33. [PMID: 16689520 DOI: 10.1021/ac060328w] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Over the past decade, electron monochromator-mass spectrometry (EM-MS) has been shown to be a selective and sensitive technique for the analysis of a wide variety of electrophilic compounds in complex matrixes. Here, for the first time, three different dinitroaniline pesticides, flumetralin, pendimethalin, and trifluralin, have been shown to be present in both mainstream and sidestream tobacco smoke using an EM-MS system. A number of cigarettes were tested that included three pure-tobacco-type cigarettes, an experimental reference cigarette, and 11 commercial cigarettes. Due to the complexity of the smoke particulate matter, the pesticides were identified only after each sample was subjected to a multistep cleanup process that included phenyl solid-phase extraction; an acid wash; aminopropyl solid-phase extraction; and finally, normal phase LC fractionation. All cigarette types tested showed the presence of the three pesticides in the tobacco smoke, with flumetralin ranging from trace levels up to 37 (+/- 9) ng/cig, pendimethalin ranging from trace levels up to 10.4 (+/- 0.6) ng/cig, and trifluralin ranging from trace levels up to 47 (+/- 17) ng/cig. Acute toxicity information is presented for the three pesticides.
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Affiliation(s)
- A John Dane
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA
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20
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Havey CD, Eberhart M, Jones T, Voorhees KJ, Laramée JA, Cody RB, Clougherty DP. Theory and Application of Dissociative Electron Capture in Molecular Identification. J Phys Chem A 2006; 110:4413-8. [PMID: 16571045 DOI: 10.1021/jp056166+] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The coupling of an electron monochromator (EM) to a mass spectrometer (MS) has created a new analytical technique, EM-MS, for the investigation of electrophilic compounds. This method provides a powerful tool for molecular identification of compounds contained in complex matrices, such as environmental samples. In particular, EM-MS has been applied to the detection of nitrated aromatic compounds, many of which are potent mutagens and/or carcinogens and are considered environmental hazards. EM-MS expands the application and selectivity of traditional MS through the inclusion of a new dimension in the space of molecular characteristics-the electron resonance energy spectrum. EM-MS also enhances detection sensitivity as well because the entire electron flux of the proper energy can be delivered into the negative ion resonance that is analytically most useful to solving the problem at hand. However, before this tool can realize its full potential, it will be necessary to create a library of resonance energy scans from standards of the molecules for which EM-MS offers a practical means of detection. Unfortunately, the number of such standards is very large and not all of the compounds are commercially available, making this library difficult to construct. Here, an approach supplementing direct measurement with chemical inference and quantum scattering theory is presented to demonstrate the feasibility of directly calculating resonance energy spectra. This approach makes use of the symmetry of the transition-matrix element of the captured electron to discriminate between the spectra of isomers. As a way of validating this approach, the resonance values for 25 nitrated aromatic compounds were measured along with their relative abundance. Subsequently, the spectra for the isomers of nitrotoluene were shown to be consistent with the symmetry-based model. The initial success of this treatment suggests that it might be possible to predict negative ion resonances and thus create a library of EM-MS standards.
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Affiliation(s)
- Crystal D Havey
- Colorado School of Mines, Department of Chemistry and Geochemistry, 1500 Illinois Street, Golden, Colorado 80401, USA
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Meetani MA, Voorhees KJ. MALDI mass spectrometry analysis of high molecular weight proteins from whole bacterial cells: pretreatment of samples with surfactants. J Am Soc Mass Spectrom 2005; 16:1422-1426. [PMID: 16023360 DOI: 10.1016/j.jasms.2005.04.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2005] [Revised: 04/08/2005] [Accepted: 04/08/2005] [Indexed: 05/03/2023]
Abstract
The use of surfactants as additives in conjunction with on-probe whole cell bacterial protein analysis employing MALDI-TOF-MS is described. Nonionic and zwitterionic surfactants were used to enhance the detection of high molecular weight proteins. Three nonionic, N-octyl-B-D-glactopyranoside, N-decyl-B-D-maltopyranoside, and N-dodecyl-B-D-maltoside, and two zwitterionic surfactants, N,N-dimethyldodecylamine-N-oxide and zwittergent 3-12 were evaluated with five different MALDI matrix systems. New peaks in the mass range of 2 to 80 kDa were produced with all of the various combinations of matrix and surfactant from both whole cell gram-positive and gram-negative bacteria. Ferulic acid used in conjunction with a 1.0 mM solution of N-octyl-B-D-glactopyranoside produced the highest quality spectra with high signal to noise ratios and peaks up to 140 kDa.
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Affiliation(s)
- Mohammed A Meetani
- Department of Chemistry and Geochemistry, Colorado School of Mines, 14th and Illinois St., 80401, Golden, CO, USA
| | - Kent J Voorhees
- Department of Chemistry and Geochemistry, Colorado School of Mines, 14th and Illinois St., 80401, Golden, CO, USA.
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Rees JC, Voorhees KJ. Simultaneous detection of two bacterial pathogens using bacteriophage amplification coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Rapid Commun Mass Spectrom 2005; 19:2757-61. [PMID: 16136521 DOI: 10.1002/rcm.2107] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The simultaneous analysis of multiple target microorganisms using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) with bacteriophage amplification is discussed. Following infection of target bacteria with specific bacteriophages, proteins contained in the progeny phage are utilized as a secondary biomarker for the target bacterium. Escherichia coli when mixed with MS2 and MPSS-1 phages specific for E. coli and Salmonella spp., respectively, at levels below their corresponding detection limits, produced only the protein (13.7 kDa) characteristic of the MS2. Likewise, Salmonella spp. when mixed with the two phages only produced a protein (13.5 kDa) characteristic of MPSS-1. When the two bacteria and the two phages were mixed together, proteins characteristic of MS2 and MPSS-1 were observed indicating that both bacteriophages had been amplified. Identification of each bacterium was made based on the presence of the secondary bacteriophage biomarkers. No deleterious effects on bacteriophage amplification were observed because of the presence of multiple bacteria or bacteriophages.
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Affiliation(s)
- Jon C Rees
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA
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Zhang Z, Wang D, Harrington PDB, Voorhees KJ, Rees J. Forward selection radial basis function networks applied to bacterial classification based on MALDI-TOF-MS. Talanta 2004; 63:527-32. [DOI: 10.1016/j.talanta.2003.11.034] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2003] [Revised: 11/11/2003] [Accepted: 11/17/2003] [Indexed: 10/26/2022]
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Madonna AJ, Voorhees KJ, Taranenko NI, Laiko VV, Doroshenko VM. Detection of cyclic lipopeptide biomarkers from Bacillus species using atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry. Anal Chem 2003; 75:1628-37. [PMID: 12705595 DOI: 10.1021/ac020506v] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel approach to microbial detection using atmospheric pressure matrix-assisted laser desorption/ionization with an ion trap mass spectrometer to analyze whole cell bacteria is introduced. This new approach was tested with lyophilized spores and cultures of Bacillus globigii (BG) grown on agar media for 4 days or longer. At each stage of growth, it was found that biomarkers, identified as cyclic lipopeptides known as fengycin and surfactin, could be detected by pulsed ultraviolet laser irradiation of intact BG cells (approximately 5 mg) cocrystallized with alpha-cyano-4-hydroxycinnamic acid. Furthermore, definitive amino acid sequence information was obtained by performing tandem mass spectrometry on the precursor ions of the cyclic lipopeptides. The investigation was broadened to include the examination of aerosolized BG spores collected from the atmosphere and directly deposited onto double-sided tape. Subsequent analysis of the recovered spores resulted in the production of mass peaks consistent with fengycin. Other Bacillus species were analyzed for comparison and showed mass spectral peaks also identified as originating from various cyclic lipopeptides. Further studies were conducted using a pulsed infrared laser as the excitation source to analyze BG cells (approximately 5 mg) suspended in a matrix of 0.03 M ammonium citrate and glycerol resulting in the production of ions characteristic of fengycin and surfactin.
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Affiliation(s)
- Angelo J Madonna
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, USA
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Madonna AJ, Van Cuyk S, Voorhees KJ. Detection of Escherichia coli using immunomagnetic separation and bacteriophage amplification coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Rapid Commun Mass Spectrom 2003; 17:257-263. [PMID: 12539193 DOI: 10.1002/rcm.900] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The application of whole cell analysis by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has emerged as a valuable tool for rapidly identifying/detecting bacteria. This technique requires minimal sample preparation and is simple to perform, but is generally limited to purified samples of bacteria at concentrations greater than 1.0 x 10(6) cells/mL. In this paper, we describe a bacterial detection method that integrates immunomagnetic separation with bacteriophage amplification prior to MALDI-MS analysis. The developed method consists of three main stages: (1) isolation of a target bacterium by immunomagnetic separation; (2) infection of the immuno-captured bacterium with a lytic bacteriophage; and (3) assay of infected medium for bacteriophage progeny using MALDI-MS to produce a molecular weight signal for the virus capsid protein. With this technique, the presence of Escherichia coli in broth was determined in less then 2 h total analysis time at a concentration of approximately 5.0 x 10(4) cells/mL.
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Affiliation(s)
- Angelo J Madonna
- Department of Chemistry, Colorado School of Mines, Golden, CO 80401, USA
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Basile F, Ferrer I, Furlong ET, Voorhees KJ. Simultaneous multiple substrate tag detection with ESI-ion trap MS for in vivo bacterial enzyme activity profiling. Anal Chem 2002; 74:4290-3. [PMID: 12199605 DOI: 10.1021/ac020249u] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A bacterial identification method in which multiple enzyme activities are measured simultaneously and in vivo with electrospray ionization-mass spectrometry (ESI-MS) is described. Whole-cell bacteria are immobilized onto a filter support and incubated with a mixture of substrates. Each substrate is chosen to measure a specific enzyme activity of a targeted bacterium and to produce a tag of unique molecular weight. After a predetermined incubation time, the solution is filtered, and the supernatant consisting of a mixture of released tags and unhydrolyzed substrates is directly analyzed, without chromatographic separation, by ESI-MS. Bacteria remain viable on the filter for further analyses. The method was tested by measuring the aminopeptidase activity of the bacteria Escherichia coli, Bacillus subtilis, Bacillus cereus, and Pseudomonas aeruginosa. The resulting aminopeptidase enzyme profiles allowed the differentiation between the four bacteria tested. The method is rapid, since a multiplex advantage is realized when assaying for multiple enzymes, and it is amenable to automation via a flow injection analysis setup.
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Allred EL, Voorhees KJ. Orientational effects on cyclopropyl participation in the thermolysis of azo compounds. Assessment of the endo configuration. J Am Chem Soc 2002. [DOI: 10.1021/ja00783a069] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Voorhees KJ, Tsao R. Smoke aerosol analysis by pyrolysis mass spectrometry/pattern recognition for assessment of fuels involved in flaming combustion. Anal Chem 2002. [DOI: 10.1021/ac00285a029] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Voorhees KJ, Hickey JC, Klusman RW. Analysis of groundwater contamination by a new surface static trapping/mass spectrometry technique. Anal Chem 2002. [DOI: 10.1021/ac00277a077] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Greenwalt CC, Voorhees KJ, Futrell JH. Transmission of organic molecules by a silicone membrane gas chromatograph/mass spectrometer interface. Anal Chem 2002. [DOI: 10.1021/ac00254a014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Voorhees KJ, Kunen SM, Durfee SL, Currie LA, Klouda GA. Characterization of airborne particulates by pyrolysis/mass spectrometry and carbon-14 analysis. Anal Chem 2002. [DOI: 10.1021/ac00232a037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Allred EL, Beck BR, Voorhees KJ. Formation of carbon-carbon double bonds by the reaction of vicinal dihalides with sodium in ammonia. J Org Chem 2002. [DOI: 10.1021/jo00926a024] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Harrington PDB, Street TE, Voorhees KJ, Radicati di Brozolo F, Odom RW. A rule-building expert system for classification of mass spectra. Anal Chem 2002. [DOI: 10.1021/ac00182a015] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ishida Y, Madonna AJ, Rees JC, Meetani MA, Voorhees KJ. Rapid analysis of intact phospholipids from whole bacterial cells by matrix-assisted laser desorption/ionization mass spectrometry combined with on-probe sample pretreatment. Rapid Commun Mass Spectrom 2002; 16:1877-1882. [PMID: 12271453 DOI: 10.1002/rcm.802] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), utilizing an on-probe sample pretreatment, was applied to the rapid and direct detection of intact phospholipids from whole bacterial cells. The sample preparation procedure involved depositing growing bacterial colonies from culture dishes directly onto the MALDI probe followed by treatment of the sample spot with a 3 micro L aliquot of an aqueous 0.05 M solution of sodium iodide prior to the addition of a 2,5-dihydroxybenzoic acid (DHB) matrix solution (ca. 8 mg dissolved in 70% acetonitrile/30% H(2)O containing 0.1% of trifluoroacetic acid). The MALDI spectra obtained from whole bacteria cells showed a series of ions generated from bacterial phospholipids, such as phosphatidylethanol-amines (PEs) and phosphatidylglycerols (PGs), which were clearly observed as well-resolved peaks. The ranges of the observed total carbon numbers in two acyl groups for PEs and PGs (30-36 and 33-36, respectively) were in good agreement with those reported previously. Furthermore, the distinct discrimination of four species of the Enterobacteriaceae family cultured identically was achieved by using principal components analysis (PCA) conducted on the relative peak intensities of phospholipids observed from the MALDI spectra.
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Affiliation(s)
- Yasuyuki Ishida
- Research Center for Advanced Energy Conversion, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
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de H, Voorhees KJ, Basile F, Hendricker AD. Validation using sensitivity and target transform factor analyses of neural network models for classifying bacteria from mass spectra. J Am Soc Mass Spectrom 2002; 13:10-21. [PMID: 11777195 DOI: 10.1016/s1044-0305(01)00345-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Temperature constrained cascade correlation networks (TCCCNs) are computational neural networks that configure their own architecture, train rapidly, and give reproducible prediction results. TCCCN classification models were built using the Latin-partition method for five classes of pathogenic bacteria. Neural networks are problematic in that the relationships among the inputs (i.e., mass spectra) and the outputs (i.e., the bacterial identities) are not apparent. In this study, neural network models were constructed that successfully classified the targeted bacteria and the classification model was validated using sensitivity and target transformation factor analysis (TTFA). Without validation of the classification model, it is impossible to ascertain whether the bacteria are classified by peaks in the mass spectrum that have no causal relationships with the bacteria, but instead randomly correlate with the bacterial classes. Multiple single output network models did not offer any benefits when compared to single network models that had multiple outputs. A multiple output TCCCN model achieved classification accuracies of 96 +/- 2% and exhibited improved performance over multiple single output TCCCN models. Chemical ionization mass spectra were obtained from in situ thermal hydrolysis methylation of freeze-dried bacteria. Mass spectral peaks that pertain to the neural network classification model of the pathogenic bacterial classes were obtained by sensitivity analysis. A significant number of mass spectral peaks that had high sensitivity corresponded to known biomarkers, which is the first time that the significant peaks used by a neural network model to classify mass spectra have been divulged. Furthermore, TTFA furnishes a useful visual target as to which peaks in the mass spectrum correlate with the bacterial identities.
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Affiliation(s)
- HarringtonPeterB de
- Center for Intelligent Chemical Instrumentation, Department of Chemistry and Biochemistry, Clippinger Laboratories, Ohio University, Athens 45701-2979, USA.
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Madonna AJ, Voorhees KJ, Hadfield TL. Rapid detection of taxonomically important fatty acid methyl ester and steroid biomarkers using in situ thermal hydrolysis/methylation mass spectrometry (THM-MS): implications for bioaerosol detection. J Anal Appl Pyrolysis 2001; 61:65-89. [PMID: 32287530 PMCID: PMC7127332 DOI: 10.1016/s0165-2370(01)00136-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2000] [Accepted: 02/21/2001] [Indexed: 05/23/2023]
Abstract
Implications for the rapid interrogation of biological materials collected from the atmosphere using a simple, one step, sample preparation technique was explored. For this purpose, various samples of whole bacteria, fungi, pollen, media contaminated with viruses, and proteins were treated with an aliquot of methanolic tetramethylammonium hydroxide prior to thermal introduction into the ion source of a triple quadrupole mass spectrometer. Molecular and fragment ions, consistent with fatty acid methyl esters (FAMEs) and steroids (non-methylated and methylated), generated during electron ionization (70 eV) of the volatile hydrolysates were subsequently detected. The varying distributions and relative intensities of these ions were used to discriminate between the different biological samples. More specifically, it was found that polyunsaturated FAMEs and steroids could be used to differentiate eukaryotic cells from prokaryotic cells since the latter do not generally synthesize either of these lipid membrane constituents. Further discrimination of the different eukaryotic samples was made based on the detection of ergosterol for fungi, cholesterol for the viral media, and C18:3Me for pollen. Multivariate statistical analysis was employed to evaluate and compare the large set of mass spectra generated during the study and to build a trained model for predicting the class membership of test samples entered as unknowns. Of 132 different samples subjected to the model as unknowns, 131 were correctly classified into their proper biological categories. Moreover, 29 out of 30 bacteria test samples representing five species of pathogenic bacteria were correctly classified at the species level.
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Affiliation(s)
- Angelo J. Madonna
- Department of Chemistry, Colorado School of Mines, Golden, CO 80401, USA
| | - Kent J. Voorhees
- Department of Chemistry, Colorado School of Mines, Golden, CO 80401, USA
| | - Ted L. Hadfield
- Armed Forces of Institute of Pathology, Washington DC 20306-6000, USA
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Madonna AJ, Basile F, Furlong E, Voorhees KJ. Detection of bacteria from biological mixtures using immunomagnetic separation combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Rapid Commun Mass Spectrom 2001; 15:1068-1074. [PMID: 11404843 DOI: 10.1002/rcm.344] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A rapid method for identifying specific bacteria from complex biological mixtures using immunomagnetic separation coupled to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry has been developed. The technique employs commercially available magnetic beads coated with polycolonal antibodies raised against specific bacteria and whole cell analysis by MALDI-MS. A suspension of a bacterial mixture is mixed with the immunomagnetic beads specific for the target microorganism. After a short incubation period (20 mins) the bacteria captured by the beads are washed, resuspended in deionized H(2)O and directly applied onto a MALDI probe. Liquid suspensions containing bacterial mixtures can be screened within 1 h total analysis time. Positive tests result in the production of a fingerprint mass spectrum primarily consisting of protein biomarkers characteristic of the targeted microorganism. Using this procedure, Salmonella choleraesuis was isolated and detected from standard bacterial mixtures and spiked samples of river water, human urine, and chicken blood.
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Affiliation(s)
- A J Madonna
- Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401, USA
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46
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Beverly MB, Voorhees KJ, Hadfield TL, Cody RB. Electron monochromator mass spectrometry for the analysis of whole bacteria and bacterial spores. Anal Chem 2000; 72:2428-32. [PMID: 10857617 DOI: 10.1021/ac991318g] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spores from a variety of Bacillus species were analyzed with direct probe mass spectrometry using an electron monochromator to select electrons of distinct energies for ionization. Electron energies were chosen to match the electron capture energies of taxonomically important compounds such as dipicolinic acid and fatty acids. Previous negative ion interferences were not observed when the monochromator was used, and the signal-to-noise ratio of targeted compounds was significantly enhanced using this approach. To demonstrate the selectivity of the technique, the monochromator was swept over a range of electron energies while monitoring the masses of compounds with known electron capture energies. Scanning the monochromator while the mass spectrometer was operated in single-ion mode enabled dipicolinic acid to be detected in 10(5) spores. The results presented here demonstrate the utility of the electron monochromator for selectively ionizing compounds directly in bacteria and bacterial spores.
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Affiliation(s)
- M B Beverly
- Chemistry and Geochemistry Department, Colorado School of Mines, Golden 80401, USA
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Madonna AJ, Basile F, Ferrer I, Meetani MA, Rees JC, Voorhees KJ. On-probe sample pretreatment for the detection of proteins above 15 KDa from whole cell bacteria by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Rapid Commun Mass Spectrom 2000; 14:2220-2229. [PMID: 11114032 DOI: 10.1002/1097-0231(20001215)14:23<2220::aid-rcm155>3.0.co;2-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A rapid methodology is described for the enhancement of the signal-to-base-line (S/B) ratio of high molecular weight protein signals from whole cell bacteria analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). The procedure involves depositing growing bacteria colonies from culture dishes directly onto the MALDI probe followed by treatment of the sample spot with a 2 microL aliquot of 40% ethanol prior to the addition of a ferulic acid matrix solution (12.5 mg dissolved in 17% formic acid/33% acetonitrile/50% H(2)O). Protein signals of more than 20 kDa were routinely produced from both Gram positive and Gram negative bacteria prepared in this manner. Moreover, a substantial number of intense protein signals were also produced in the more 'conventional' fingerprint region extending from 4 to 20 kDa. This approach is rapid, easy to implement into existing methodologies, and does not require any special hardware.
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Affiliation(s)
- A J Madonna
- Department of Chemistry, Colorado School of Mines, Golden, CO 80401, USA
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Holland RD, Rafii F, Heinze TM, Sutherland JB, Voorhees KJ, Lay JO. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometric detection of bacterial biomarker proteins isolated from contaminated water, lettuce and cotton cloth. Rapid Commun Mass Spectrom 2000; 14:911-7. [PMID: 10825256 DOI: 10.1002/(sici)1097-0231(20000530)14:10<911::aid-rcm965>3.0.co;2-c] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectra of bacterial proteins were obtained from water, lettuce and cloth samples contaminated with Shigella flexneri, Escherichia coli, and Aeromonas hydrophila. Spectra were obtained using proteins directly isolated from water (or water used for rinsing samples) without culturing the bacteria. For S. flexneri and E. coli, two marker ions for specific proteins associated with a virulence-related property (acid resistance) were easily detected. For A. hydrophila, ions from two specifically selected marker proteins, as well as ions from the larger group of proteins isolated from pure cultures, all matched spectra from a contaminated water sample, providing strong evidence that A. hydrophila was the bacterial contaminant. Rinse water from contaminated lettuce and cloth samples showed the same marker ions as the contaminated water samples.
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Affiliation(s)
- R D Holland
- National Center for Toxicological Research, Jefferson, AR 72079, USA
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Beverly MB, Basile F, Voorhees KJ, Hadfield TL. The effects of electron and chemical ionization modes on the MS profiling of whole bacteria. J Am Soc Mass Spectrom 1999; 10:747-758. [PMID: 10439512 DOI: 10.1016/s1044-0305(99)00050-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Free fatty acid profiling of whole bacteria [Francisella tularensis, Brucella melitensis, Yersinia pestis, Bacillus anthracis (vegetative and sporulated), and Bacillus cereus] was carried out with direct probe mass spectrometry under 70-eV electron ionization (EI) and isobutane chemical ionization in both the positive (CI+) and negative modes (CI-). Electron ionization produced spectra that contained molecular ions and fragment ions from various free fatty acids. Spectra acquired with isobutane chemical ionization in the positive mode yielded molecular ions of free fatty acids as well as ions from other bacterial compounds not observed under EI conditions. Spectra obtained with negative chemical ionization did not contain as much taxonomic information as EI or CI+; however, some taxonomically significant compounds such as dipicolinic acid and poly(3-hydroxybutyrate) did produce negative ions. All ionization modes yielded spectra that could separate the bacteria by Gram-type when observed with principle components analysis (PCA). Chemical ionization in the positive ion mode produced the greatest amount of differentiation between the four genera of bacteria when the spectra where examined by PCA.
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Affiliation(s)
- M B Beverly
- Chemistry and Geochemistry Department, Colorado School of Mines, Golden 80401, USA
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Holland RD, Duffy CR, Rafii F, Sutherland JB, Heinze TM, Holder CL, Voorhees KJ, Lay JO. Identification of bacterial proteins observed in MALDI TOF mass spectra from whole cells. Anal Chem 1999; 71:3226-30. [PMID: 10450164 DOI: 10.1021/ac990175v] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Characteristic ions in the MALDI TOF mass spectra from bacterial cells have been associated with four known proteins. The proteins, observed both from cells and in filtered cellular suspensions, were isolated by HPLC and identified on the basis of their mass spectra and their partial amino acid sequence, determined using the Edman method (10-15 residues). The acid resistance proteins HdeA and HdeB give rise to ions near m/z 9735 and 9060 in MALDI TOF mass spectra from cells and from extracts of both Escherichia coli 1090 and Shigella flexneri PHS-1059. However, the proteins associated with proteolytic cleavage by the peptidase Lep, rather than the precursor proteins, were observed, both using cells and from cellular extracts. A cold-shock protein, CspA, was associated with the ion near m/z 7643 from Pseudomonas aeruginosa. Similarly, a cold-acclimation protein, CapB, was identified as the source of the ion near m/z 7684 in P. putida. This last protein was homologous with a known CapB from P. fragi. While these experiments involved the detection of known or homologous proteins from typical bacteria, this same approach could also be applied to the detection of unique proteins or biomarker proteins associated with other bacteria of public health significance.
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Affiliation(s)
- R D Holland
- Division of Chemistry, Food and Drug Administration, Jefferson, Arkansas 72079, USA
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