Effect of formaldehyde exposure on bacterial communities in simulating indoor environments

Indoor formaldehyde (CH(2)O) exceeding the recommended level is a severe threat to human health. Few studies have investigated its effect on indoor surface bacterial communities, affecting habitants' health. This study used 20-L glass containers to mimic the indoor environment with bacterial inputs from human oral respiration. The behavior of bacterial communities responding to CH(2)O varied among the different CH(2)O levels. The bacterial community structure significantly changed over time in the 0.054 mg·m(−3) CH(2)O group, which varied from the 0.1 mg·m(−3) and 0.25 mg·m(−3) CH(2)O groups. The Chao1 and Shannon index significantly increased in the 0.054 mg·m(−3) CH(2)O group at 6 week, while they remained unchanged in the 0.25 mg·m(−3) CH(2)O group. At 12 week, the Chao1 significantly increased in the 0.25 mg·m(−3) CH(2)O group, while it remained unchanged in the 0.054 mg·m(−3) CH(2)O group. Only a few Operational Taxonomic Units (OTUs) significantly correlated with the CH(2)O concentration. CH(2)O-induced OTUs mainly belong to the Proteobacteria and Firmicutes. Furthermore, bacterial communities formed at 6 or 12 weeks differed significantly among different CH(2)O levels. Functional analysis of bacterial communities showed that inferred genes related to chemical degradation and diseases were the highest in the 0.25 mg·m(−3) CH(2)O group at 12 weeks. The development of nematodes fed with bacteria collected at 12 weeks was applied to evaluate the bacterial community's hazards. This showed significantly impaired growth in the 0.1 mg·m(−3) and 0.25 mg·m(−3) CH(2)O groups. These findings confirmed that CH(2)O concentration and exposure time could affect the indoor bacterial community and formed bacterial communities with a possibly more significant hazard to human health after long-term exposure to high CH(2)O levels.