title: Microbial communities related to volatile organic compound emission in automobile air conditioning units.
abstract: During operation of mobile air conditioning (MAC) systems in automobiles, malodours can occur. We studied the microbial communities found on contaminated heat exchanger fins of 45 evaporators from car MAC systems which were operated in seven different regions of the world and identified corresponding volatile organic compounds. Collected biofilms were examined by scanning electron microscopy and fluorescent in situ hybridization. The detected bacteria were loosely attached to the metal surface. Further analyses of the bacteria using PCR-based single-strand conformation polymorphism and sequencing of isolated 16S rRNA gene fragments identified highly divergent microbial communities with multiple members of the Alphaproteobacteriales, Methylobacteria were the prevalent bacteria. In addition, Sphingomonadales, Burkholderiales, Bacillales, Alcanivorax spp. and Stenotrophomonas spp. were found among many others depending on the location the evaporators were operated. Interestingly, typical pathogenic bacteria related to air conditioning systems including Legionella spp. were not found. In order to determine the nature of the chemical compounds produced by the bacteria, the volatile organic compounds were examined by closed loop stripping analysis and identified by combined gas chromatography/mass spectrometry. Sulphur compounds, i.e. di-, tri- and multiple sulphides, acetylthiazole, aromatic compounds and diverse substituted pyrazines were detected. Mathematical clustering of the determined microbial community structures against their origin identified a European/American/Arabic cluster versus two mainly tropical Asian clusters. Interestingly, clustering of the determined volatiles against the origin of the corresponding MAC revealed a highly similar pattern. A close relationship of microbial community structure and resulting malodours to the climate and air quality at the location of MAC operation was concluded.
authors.affiliation: AMODIA Bioservice GmbH, Rebenring 31, 38106, Braunschweig, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Diekmann
authors.forename: Melanie
authors.initials: M
authors.lastname: Burghartz
authors.forename: Lars
authors.initials: L
authors.lastname: Remus
authors.forename: Anna-Lena
authors.initials: AL
authors.lastname: Kaufholz
authors.forename: Thorben
authors.initials: T
authors.lastname: Nawrath
authors.forename: Manfred
authors.initials: M
authors.lastname: Rohde
authors.forename: Stefan
authors.initials: S
authors.lastname: Schulz
authors.forename: Louisa
authors.initials: L
authors.lastname: Roselius
authors.forename: Jörg
authors.initials: J
authors.lastname: Schaper
authors.forename: Oliver
authors.initials: O
authors.lastname: Mamber
authors.forename: Dieter
authors.initials: D
authors.lastname: Jahn
authors.forename: Martina
authors.initials: M
authors.lastname: Jahn
mesh_terms: D000389:Air Conditioning / Q000295:instrumentation*; D001336:Automobiles; D001419:Bacteria / Q000145:classification* / Q000254:growth & development / Q000378:metabolism*; D018407:Bacterial Physiological Phenomena; D018441:Biofilms / Q000254:growth & development*; D058448:Biota; D002980:Climate; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004783:Environmental Microbiology; D008401:Gas Chromatography-Mass Spectrometry; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D055549:Volatile Organic Compounds