Bacillus-Dominant Airborne Bacterial Communities Identified During Asian Dust Events

Aeromicrobiology: A global review of the cycling and relationships of bioaerosols with the atmosphere

Airborne microorganisms and biological matter (bioaerosols) play a key role in global biogeochemical cycling, human and crop health trends, and climate patterns. Their presence in the atmosphere is controlled by three main stages: emission, transport, and deposition. Aerial survival rates of bioaerosols are increased through adaptations such as ultra-violet radiation and desiccation resistance or association with particulate matter. Current research into modern concerns such as climate change, global gene transfer, and pathogenicity often neglects to consider atmospheric involvement. This comprehensive review outlines the transpiring of bioaerosols across taxa in the atmosphere, with significant focus on their interactions with environmental elements including abiotic factors (e.g., atmospheric composition, water cycle, and pollution) and events (e.g., dust storms, hurricanes, and wildfires). The aim of this review is to increase understanding and shed light on needed research regarding the interplay between global atmospheric phenomena and the aeromicrobiome. The abundantly documented bacteria and fungi are discussed in context of their cycling and human health impacts. Gaps in knowledge regarding airborne viral community, the challenges and importance of studying their composition, concentrations and survival in the air are addressed, along with understudied plant pathogenic oomycetes, and archaea cycling. Key methodologies in sampling, collection, and processing are described to provide an up-to-date picture of ameliorations in the field. We propose optimization to microbiological methods, commonly used in soil and water analysis, that adjust them to the context of aerobiology, along with other directions towards novel and necessary advancements. This review offers new perspectives into aeromicrobiology and calls for advancements in global-scale bioremediation, insights into ecology, climate change impacts, and pathogenicity transmittance.

Environmental processes and health implications potentially mediated by dust-borne bacteria

Understanding microbial migration and survival mechanisms in dust events (DEs) can elucidate genetic and metabolic exchange between environments and help predict the atmospheric pathways of ecological and health-related microbial stressors. Dust-borne microbial communities have been previously characterized, but the impact and interactions between potentially active bacteria within transported communities remain limited. Here, we analysed samples collected during DEs in Israel, using amplicon sequencing of the 16S rRNA genes and transcripts. Different air trajectories and wind speeds were associated not only with the genomic microbial community composition variations but also with specific 16S rRNA bacterial transcripts. Potentially active dust-borne bacteria exhibited positive interactions, including carbon and nitrogen cycling, biotransformation of heavy metals, degradation of organic compounds, biofilm formation, and the presence of pathogenic taxa. This study provides insights into the potential interactive relationships and survival strategies of microorganisms within the extreme dust environment.

Adverse impacts of Asian dust events on human health and the environment-A probabilistic risk assessment study on particulate matter-bound metals and bacteria in Seoul, South Korea

This study aimed to assess the impact of Asian dust (AD) on the human health and the environment. Particulate matter (PM) and PM-bound trace elements and bacteria were examined to determine the chemical and biological hazards associated with AD days and compared with non-AD days in Seoul. On AD days, the mean PM10 concentration was ∼3.5 times higher than that on non-AD days. Elements generated from the Earth's crust (Al, Fe, and Ca) and anthropogenic sources (Pb, Ni, and Cd) were identified as major contributors to coarse and fine particles, respectively. During AD days, the study area was recognized as "severe" for pollution index and pollution load index levels, and "moderately to heavily polluted" for geoaccumulation index levels. The potential cancer risk (CR) and non-CR were estimated for the dust generated during AD events. On AD days, total CR levels were significant (in 1.08 × 10^-5-2.22 × 10^-5), which were associated with PM-bound As, Cd, and Ni. In addition, inhalation CR was found to be similar to the incremental lifetime CR levels estimated using the human respiratory tract mass deposition model. In a short exposure duration (14 days), high PM and bacterial mass deposition, significant non-CR levels, and a high presence of potential respiratory infection-causing pathogens (Rothia mucilaginosa) were observed during AD days. Significant non-CR levels were observed for bacterial exposure, despite insignificant levels of PM10-bound elements. Therefore, the substantial ecological risk, CR, and non-CR levels for inhalation exposure to PM-bound bacteria, and the presence of potential respiratory pathogens, indicate that AD events pose a significant risk to both human lung health and the environment. This study provides the first comprehensive examination of significant non-CR levels for bacteria and carcinogenicity of PM-bound metals during AD events.

Environmental sporobiota: Occurrence, dissemination, and risks

Spore-forming bacteria known as sporobiota are widespread in diverse environments from terrestrial and aquatic habitats to industrial and healthcare systems. Studies on sporobiota have been mainly focused on food processing and clinical fields, while a large amount of sporobiota exist in natural environments. Due to their persistence and capabilities of transmitting virulence factors and antibiotic resistant genes, environmental sporobiota could pose significant health risks to humans. These risks could increase as global warming and environmental pollution has altered the life cycle of sporobiota. This review summarizes the current knowledge of environmental sporobiota, including their occurrence, characteristics, and functions. An interaction network among clinical-, food-related, and environment-related sporobiota is constructed. Recent and effective methods for detecting and disinfecting environmental sporobiota are also discussed. Key problems and future research needs for better understanding and reducing the risks of environmental sporobiota and sporobiome are proposed.

Spatio-temporal variations of airborne bacteria from the municipal wastewater treatment plant: a case study in Ahvaz, Iran

The study of bioaerosol dispersion in wastewater treatment plants (WWTPs) has received considerable attention. This study aimed to investigate the seasonal changes and spatial distributions of airborne bacteria around different parts of Ahvaz WWTP, the capital city of Khuzestan Province, Iran, over 4 months in the cold and warm seasons. Samples were collected from 2 and 10-m intervals of grit chamber (GCh), primary sludge dewatering basin (PSDB), aeration tank (AT), as well as 60-m upstream (US) and downstream (DS) of the WWTP. Further, bacteria in the indoor air of administrative building (AB) of WWTP were investigated. Bioaerosols were collected by passive sampling method. The total bacteria count was 105.3 ± 98.5 CFU/plate/h. The dominant bacteria stood 2 m away from the AT with an average 244.2 ± 73.1 CFU/plate/h in the warm season while they were the lowest with an average 43 ± 11.4 CFU/plate/h in the 10-m distance of the GCh in the cold season. According to the sequencing results, the dominant bacterial species included Bacillus pumilus (26.7%), Staphylococcus arlettae (23.2%), Kocuria turfanensis (13.6%) and Alicycliphilus (9.2%), respectively. There was a positive relationship between the release of bacteria, temperature and wind speed. However, there was a significant negative correlation between total bacteria concentration and humidity. There are accumulative perils to WWTP workers and neighbors exposed by persistent exposure to airborne bacteria. Therefore, AT should be paid more attention as a dominant source of airborne bacteria emissions, especially in the warm season.