Spatial Variation in the Healthy Human Lung Microbiome and the Adapted Island Model of Lung Biogeography

To determine if the lung microbiome is spatially varied in healthy adults.

Bronchoscopy was performed on 15 healthy subjects. Specimens were sequentially collected in the lingula and right middle lobe (by bronchoalveolar lavage [BAL]), then in the right upper lobe, left upper lobe, and supraglottic space (by protected-specimen brush). Bacterial 16S ribosmal RNA-encoding genes were sequenced using MiSeq (Illumina, San Diego, CA). MEASUREMENTS AND MAIN RESULTS: There were no significant differences between specimens collected by BAL and protected-specimen brush. Spatially separated intrapulmonary sites, when compared with each other, did not contain consistently distinct microbiota. On average, intrasubject variation was significantly less than intersubject variation (P = 0.00003). By multiple ecologic parameters (community richness, community composition, intersubject variability, and similarity to source community), right upper lobe microbiota more closely resembled those of the URT than did microbiota from more distal sites. As predicted by the adapted island model, community richness decreased with increasing distance from the source community of the URT (P