Copper Alloys Were Frequently Able to Sustain Bacterial Concentrations at or near Those Prescribed upon Completion of Terminal Cleaning

(...) We examined the microbiological composition and abundance in space and time of bioaerosols collected in the Barcelona subway system during a cold period. (...) Multitag 454 pyrosequencing of the 16S rRNA gene was used to assess bacterial community composition and biodiversity. The results showed low bioaerosol concentrations regarding the targeted microorganisms, although the bacterial bioburden was rather high (104 bacteria/m3). Airborne bacterial communities presented a high degree of overlap among the different subway environments sampled (inside trains, platforms and lobbies) and were dominated by a few widespread taxa, with Methylobacterium being the most abundant genus. (...) Overall, we found that commuters are not the main source of bioaerosols in the Barcelona subway system.