Characterisation of the Microbial Community in Indoor Environments: a Chemical-Analytical Approach

Aleksandra Sebastian

Research output: ThesisDoctoral Thesis (compilation)

131 Downloads (Pure)

Abstract

Inhalation of airborne microorganisms and their toxic components and products may induce a wide spectrum of acute and chronic airway manifestations. The study describes important capabilities of chemical marker analysis in defining human exposure to microorganisms in indoor environments. An integrated procedure is presented where gas chromatography - ion trap tandem mass spectrometry is used to determine chemical markers of gram-negative bacterial lipopolysaccharide (3-hydroxy fatty acids with 10-16 carbon atoms), gram-positive bacteria (branched-chain fatty acids with 15 and 17 carbon atoms), bacterial peptidoglycan (muramic acid), and fungal biomass (ergosterol). A hydrolysate of 13C-labelled cyanobacterial cells was used as an internal standard for the first three markers (13C-labelled 3-hydroxytridecanoic acid from labelled Pectinatus cerevisiiphilus was used as an alternative internal standard to improve quantification of the 3-hydroxy fatty acids) and dehydrocholesterol served as an internal standard for ergosterol. These analyses required two 1-5 mg dust samples, one for 3-hydroxy fatty acids, non-hydroxylated fatty acids and muramic acid, and another for ergosterol. The method was used to distinguish between microbial communities in settled and air-borne house dust samples collected from different locations indoors. Both quantitative and qualitative (marker profiles) differences were detected among the studied locations. Air concentrations of 3-hydroxytetradecanoic acid were 4-63 times higher in rooms of smoking students than in parallel rooms of non-smoking students demonstrating that cigarette smoke may be a major source of endotoxin in indoor environments. Settled dust (collected on the floor and from surfaces above the floor) did not show different amounts of lipopolysaccharide with regard to smoking. A school survey demonstrated that the levels of muramic acid were much higher in occupied rooms than in the same rooms when unoccupied. Notably, the levels of 3-hydroxy fatty acids were only slightly higher in occupied than unoccupied rooms suggesting an alteration in bacterial population. Also the particle size distribution in schoolrooms was shown to be quite different in occupied than in unoccupied rooms. This thesis has resulted in the development of a universally applicable method for characterising microbial populations in matrices that are complex chemically. This method forms a basis for epidemiological studies on health consequences upon microbial exposure in indoor environments.
Original languageEnglish
QualificationDoctor
Awarding Institution
  • Department of Translational Medicine
Supervisors/Advisors
  • Larsson, Lennart, Supervisor
Award date2005 Oct 3
Publisher
Print ISBNs91-628-6591-9
Publication statusPublished - 2005

Bibliographical note

Defence details

Date: 2005-10-03
Time: 13:00
Place: Department of Laboratory Medicine Div. of Medical Microbiology Sölvegatan 23 223 62 Lund Patologen Förläsningssal

External reviewer(s)

Name: Norbäck, Dan
Title: Docent
Affiliation: Institutionen för Medicinska Vetenskaper Arbets- och Miljömedicin Akademiska Sjukhuset, Uppsala

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<div class="article_info">A. Sebastian and L. Larsson. <span class="article_issue_date">2003</span>. <a href="javascript:downloadFile(545255)" class="article_link">Characterisation of the microbial community in indoor environments : a chemical-analytical approach</a> <span class="journal_series_title">Applied and environmental microbiology</span>, <span class="journal_volume">vol 69</span> <span class="journal_pages">pp 3103-3109</span>. <span class="journal_distributor">American Society for Microbiology (ASM)</span></div>
<div class="article_info">A. Sebastian, A. Fox, W. Harley and L Larsson. <span class="article_issue_date">2004</span>. <span class="article_title">Evaluation of muramic acid ester O-methyl acetate derivative for the determination of peptidoglycan in environmental samples by ion-trap GC-MSMS</span> <span class="journal_series_title">Journal of environmental monitoring / JEM</span>, <span class="journal_volume">vol 6</span> <span class="journal_pages">pp 300-304</span>. <span class="journal_distributor">Royal Society of Chemistry</span></div>
<div class="article_info">A. Sebastian, B. Szponar and L. Larsson. <span class="article_issue_date">2005</span>. <a href="javascript:downloadFile(545257)" class="article_link">Characterization of the microbial community in indoor environments by chemical marker analysis : an update and critical evaluation</a> <span class="journal_series_title">Indoor air : international journal of indoor air quality and climate</span>, <span class="journal_volume">vol 15</span> <span class="journal_pages">pp 20-26</span>. <span class="journal_distributor">Blackwell</span></div>
<div class="article_info">A. Sebastian, C. Pehrson and L. Larsson.. <span class="article_issue_date"></span>. <span class="article_title">Tobacco smoke introduces large amounts of endotoxin into indoor air</span> (manuscript)</div>
<div class="article_info">A. Fox, W. Harley, A.C. Feigley, D. Salzberg, A. Sebastian and L. Larsson.. <span class="article_issue_date">2005</span>. <span class="article_title">Large particles are responsible for elevated bacterial marker levels in school air upon occupation</span> <span class="journal_series_title">Journal of environmental monitoring / JEM</span>, <span class="journal_volume">vol 7</span> <span class="journal_pages">pp 450-456</span>. <span class="journal_distributor">Royal Society of Chemistry</span></div>

Subject classification (UKÄ)

  • Clinical Medicine

Keywords

  • indoor air
  • microbial chemical markers
  • asthma
  • allergies
  • tobacco smoke
  • Infektioner
  • Infections

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