Bacterial communities at airport assessed by high-throughput sequencing

Background. Air travel enables rapid global transport of infectious diseases. Hub airports visited by hundreds of thousands of passengers a day are potential environments for spreading infectious diseases. Therefore, airports need a functional prevention mechanism and a response plan in case of a disease outbreak. With growing number of passengers, the contaminated surfaces could play an important role in spreading the diseases. Sufficient understanding of the microbial communities on surfaces, which could come in contact with the passengers, can facilitate the development of rapid, sensitive and specific tools for monitoring the microorganisms of interest.Objectives. In this study we concentrated on the characterization of bacterial populations recovered from the frequent contact surfaces at an airport.Methods. Sixty different surfaces at the airport were swabbed three times with an interval of 2 weeks. Bacterial numbers were assessed using q-PCR. Bacterial population profiles from 44 samples (22 sampling points, sampled twice) were characterized by high-throughput sequencing. The amplicon library of V3-V4 variable region of 16S rRNA genes was constructed and sequenced on the IonTorrent platform. The sequence data were quality filtered and analyzed using the mothur software. Sequences were classified using the RDP Bayesian Classifier (80% confidence) and clustered into phenotypes at different phylogenetic levels.Results. 142 062 good quality sequences were obtained from all 44 samples. The sequences were grouped into 569 phylotypes at genus level. A total of 21 bacterial phyla were detected. More than 97% of all sequences were assigned to the predominant phyla Actinobacteria, Proteobacteria and Firmicutes. These were the only phyla present in all 44 samples analyzed. The phylum Firmicutes was represented by two classes, Bacilli and Clostridia. The main proteobacterial classes were Gamma- and Alphaproteobacteria. The phylum Actinobacteria was entirely represented by the class Actinobacteria. Most of the genera were identified to be human associated.Conclusions. This study reveals diverse bacterial populations present on all surfaces at the airport. The dynamics of the bacterial populations were followed for two weeks and the results showed that bacterial community profiles sometimes differed between the different sampling times.