Contaminazione microbica dell’aria in metropolitana

Culture-Independent Analysis of Aerosol Microbiology in a Metropolitan Subway 

The  goal  of  this  study  was  to  determine  the  composition  and  diversity  of   microorganisms associated with bioaerosols in a heavily trafficked metropolitan subway   environment.  We collected bioaerosols by fluid impingement on several New York City  subway  platforms  and  associated  sites  in  three  sampling  sessions  over  a  1½  year  period.    The  types  and  quantities  of  aerosolized  microorganisms  were  determined  by   culture-independent   phylogenetic   analysis   of   small-subunit   ribosomal   RNA   gene  sequences, using both Sanger (universal) and pyrosequencing (bacterial) technologies.  

Overall  the  subway  bacterial  composition  was  relatively  simple;  only  26  taxonomic  families made up ~75% of sequences determined.  The microbiology was more or less  similar throughout the system and with time, and most similar to outdoor air, consistent  with highly efficient air mixing in the system.  Identifiable bacterial sequences indicated  that  the  subway  aerosol  assemblage  was  composed  of  a  mix  of  genera  and  species  characteristic  of  soil,  environmental  water,  and  human  skin  commensal  bacteria.  

Eukaryotic  diversity  was  mainly  fungal,  dominated  by  organisms  of  types  associated   with wood rot.  Human skin bacterial species (at 99% rRNA sequence identity) included  the Staphylococcus spp. S. epidermidis (the most abundant and prevalent commensal  of  the  human  integument),  S.  hominus,  S.  cohnii,  S.  caprae  and  S.  haemoliticus,  all  well-documented human commensal bacteria.  We encountered no organisms of public  health concern.  This study is the most extensive culture-independent survey of subway   microbiota  so  far  and  puts  in  place  pre-event  information  required  for  any  bioterror  surveillance  activities  or  monitoring  of  the  microbiological  impact  of  recent  subway  flooding events.