Molecular bacterial diversity and bioburden of commercial airliner cabin air

Culture-independent, biomarker-targeted bacterial enumeration and identification strategies were employed to estimate total bacterial burden and diversity within the cabin air of commercial airliners. Samples from each of 4 flights on 2 commercial carriers were collected via air-impingement. The total viable microbial population ranged from below detection limits to 4.1 x 10(6) cells/m(3) of air, as assessed by the ATP assay. A gradual accumulation of microbes was observed from the time of passenger boarding through mid-flight, followed by a sharp decline in bacterial abundance and viability from the initiation of descent through landing. Representatives of the alpha-, beta-, and gamma-Proteobacteria, as well as Gram-positive bacteria, were isolated in varying abundance. Neisseria meningitidis rRNA gene sequences were retrieved in great abundance from Airline A followed by Streptococcus oralis/mitis sequences. Pseudomonas synxantha sequences dominated Airline B clone libraries, followed by those of N. meningitidis and S. oralis/mitis. The cabin air samples examined herein housed low bacterial diversity and were often dominated by a particular subset of bacteria: opportunistic pathogenic inhabitants of the human respiratory tract and oral cavity.