Airborne microbial abundance and pathogenicity in China and Europe
Around the world, airborne microbes are widely distributed in urban areas, and play a vital role in channeling the transmission of microbes across the atmosphere, biosphere, and anthroposphere. The automobile air conditioning (AAC) filters can act as samplers to trap the atmospheric particles including airborne microbes to reflect the transmission of them and potentially some infectious diseases in certain areas. This study randomly collected AAC filters from China (Guangzhou and Beijing) and Europe (Munich, Lyon, Villeurbanne, and Birkerod). Through colony culture count, it was found that the average concentration of culturable bioaerosols in China was higher than in Europe. Through high-throughput sequencing analysis, we identified the dominant pathogenic microorganism in Chinese and European cities, Mycobacterium is the most abundant pathogenic bacterium (18.19% in Guangzhou,18.99% in Beijing,18.09% in Birkerod,20.47% in Munich,15.35% in Lyon, and 24.63% in Villeurbanne), meanwhile, Bartonella and Bordetella are also widely distributed. Cladosporium was identified as the main pathogenic fungi both in China and Europe(23.04% in Guangzhou,30.17% in Beijing,37.71% in Birkerod,30.71% in Munich, 24.98% in Lyon, and 29.30% in Villeurbanne). BugBase phenotypic prediction results showed significant differences in the phenotypes of Chinese and European urban bacterial communities in terms of mobile elements and biofilm formation. Most bacteria are inversely associated with heavy metals; fungi are more tolerant. To counteract the damage caused by metal exposure, microbes have evolved a variety of metal resistance genes. Therefore, the coexistence of heavy metals and pathogens in an urban atmospheric environment may lead to double biochemical pollution. The proposed AAC filter-based bioaerosol measurement can create surveillance network, which will potentially complement public health systems with early warning ability for global health risks.