Community structure of bacteria and fungi in aerosols of a pig confinement building

Modern intensive husbandry practices can create poor indoor air quality, with high levels of airborne dust, endotoxins, ammonia, and microorganisms. Air in a sow breeding barn was investigated to determine the biomass composition of bioaerosols using molecular methods supplemented with microscopic and cultivation‐dependent approaches. A total of 2.7 ± 0.7 × 10 7  bacterial cells m −3 air and 1.2 ± 0.3 × 10 6  fungi spores m −3 were detected, corresponding to the fungal biovolume constituted 98% of the total microbial biovolume (fungal and bacterial). Fifty‐two percent of all 4′,6‐diamidino‐2‐phenyl indole‐stained cells were detectable with fluorescence in situ hybridization ( FISH ) with a general bacterial probe mixture. Quantitative FISH of the bacterial consortium revealed F irmicutes as the dominant group with S treptococcus as the major genus, while A ctinobacteria constituted 10% of the detectable bacteria. Additionally, the study revealed an abundant and diverse fungal community including species not previously found in similar environments. The most abundant fungal 18S rRNA gene clone sequences identified affiliated with the A spergillus – E urotium cluster, but among others, species of W allemia , M ucorales , and R ussulales were detected. For both fungi and anaerobic bacteria, a hitherto undescribed diversity was found in bioaerosols from a modern sow breeding barn, which potentially could create poor indoor air quality, although their effect on the health of farmworkers and stock still is not resolved.