The air we breathe contains millions of microbes, yet we are largely unaware of what they are, what they do and how they respond to changing environmental conditions. Air is a key route of global microorganism cycling and a major source of human microbial exposure, but it remains the last of the Earth’s major ecosystems (after terrestrian and aquatic) to be explored for microbial life.
Each cubic meter of air contains thousands to millions of diverse microorganisms – fungi, bacteria, archaea, and viruses – aerosolised from humans and a variety of environmental sources, and influenced by factors including particle size, airflow, irradiation and humidity. Indoors, air is filtered and recirculated, and occupants and surfaces can act as sources and sinks, accumulating and resuspending settled or filtered biological and particulate matter. Evidence is emerging that airborne microorganisms in indoor spaces can differ substantially from outdoor communities, with less diversity and higher bacterial loads. However, the extent and impact of such changes on indoor and airborne microbial communities are not understood, particularly in the tropics.
SCELSE’s Air Microbiome integrated programme focuses on Singapore’s urbanised tropical environment. Modern tropical locations are unique because they offer a range of natural and artificial climatic conditions, to which the microbes respond. Central ventilation and cooling systems may quickly bring relief to the hot ambient temperatures and high humidity, but this action may result in changes to the air microbial composition, function and activity. Increasing numbers of people are spending more and more time indoors, immersed in surrounding microbial conditions that have yet to be discerned. Exercising control over the conditions of circulating air such as pressure and humidity may provide a means to reduce or eliminate potential health risks.
Technological advancements are only now enabling the effective extraction of biological information from the air in the form of DNA and RNA. Deriving knowledge from such samples requires an approach that encompasses not only genomics, but also microbial ecology, chemistry and physics. The Air Microbiome programme adopts such a multidisciplinary approach in its pioneering exploration of the sources, function and ecology of urban air microbiomes in this little-explored ecosystem. The research employs sampling designs informed by aerosol physics and theoretical frameworks based on ecology, adaptive responses and systems biology. Experimental aerosol systems explore microbial interactions and behaviours that are unique to the air microbiome.
Specific research themes for this programme include:
- Environmental genomics – investigating the diverse microbiological communities of unknown composition and function harboured by air;
- Ecological connectivity – describing the dynamic network of sources and sinks that exists in the urban air ecosystem;
- Adaptive responses – understanding how physicochemical parameters induce molecular responses in airborne microbiota.