Bacteria influence site-specific disease etiology and the host's ability to metabolize
xenobiotics, such as
polycyclic aromatic hydrocarbons (PAHs).
Lung cancer in Xuanwei, China has been attributed to PAH-rich household air pollution from burning
coal. This study seeks to explore the role of lung microbiota in
lung cancer among never smoking Xuanwei women and how
coal burning may influence these associations.
DNA from sputum and buccal samples of never smoking
lung cancer cases (n = 8, in duplicate) and controls (n = 8, in duplicate) in two Xuanwei villages was extracted using a multi-step enzymatic and physical lysis, followed by a standardized clean-up. V1-V2 regions of
16S rRNA genes were PCR-amplified. Purified amplicons were sequenced by 454 FLX
Titanium pyrosequencing and high-quality sequences were evaluated for diversity and taxonomic membership. Bacterial diversity among cases and controls was similar in buccal samples (P = 0.46), but significantly different in sputum samples (P = 0.038). In sputum, Granulicatella (6.1 vs. 2.0%; P = 0.0016), Abiotrophia (1.5 vs. 0.085%; P = 0.0036), and Streptococcus (40.1 vs. 19.8%; P = 0.0142) were enriched in cases compared with controls. Sputum samples had on average 488.25 species-level OTUs in the flora of cases who used smoky
coal (PAH-rich) compared with 352.5 OTUs among cases who used
smokeless coal (PAH-poor; P = 0.047). These differences were explained by the Bacilli species (Streptococcus infantis and Streptococcus anginosus). Our small study suggests that never smoking
lung cancer cases have differing sputum microbiota than controls. Further, bacteria found in sputum may be influenced by environmental exposures associated with the type of
coal burned in the home.