AN ATMOSPHERIC SIMULATION CHAMBER TO INVESTIGATE DUST-BORNE MICROBIOTA COMPOSITION AND VIABILITY

Dust stormsfrom the desert areas, in particular from the Sahara, are the principal source of dust in the atmosphere, capable of dust dispersion and transport over very long distances. Dust clouds may contain high concentrations of microbiota, e.g. fungal spores, plant pollen, algae, bacteria. Bioaerosols associated with dust events can spread pathogens over long distances and can impact ecosystem equilibria, human health and yield of agricultural products. For many microorganisms long-range and high-altitude transport in the free atmosphere can be very stressful due to strong ultraviolet radiation, low humidity (inducing desiccation), too low or too high temperatures, and complex atmospheric chemistry (e.g. presence of radicals or other reactive species). Only specially resistant organisms are able to survive, so microbiota population composition can change during the long airborne transport to the final site of deposition. In this work we summarize the first results on the use of ChAMBRe (Chamber for Aerosol Modelling and Bio-aerosol Research), an atmospheric simulation chamber designed and implemented at the Physics Department of the University of Genoa, in cooperation with INFN (National Institute of Nuclear Physics) to investigate bioaerosol evolution and transformation under different atmospheric conditions. ChAMBRe is the first Italian facility of this type, specifically conceived to study the mechanisms of interaction between bioaerosols and other particles or chemical compounds usually present in the atmosphere. We describe the experimental setup and the protocols to inject, monitor, analyze and extract Gram-positive and Gram-negative model bacteria, bacillus subtilis and escherichia coli respectively. In this initial stage we focused primarily on crucial operational aspects such as growth and injection of suitable amounts of bacteria, measurement of the average lifetime inside the chamber, extraction and sampling, identification of the steps involving the major stress for the microorganisms under investigation.