An atmospheric simulation chamber to investigate dust-borne microbiota composition and viability

Dust storm activity from the largest deserts on the earth, in particular from the North Africa regions, is 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 ecosystems 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 reactive radicals). Only specially resistant organisms are able to survive, so microbiota population composition changes during the long airborne transport to the final site of deposition. In this work we summarize the principal characteristics of ChAMBRe (Chamber for Aerosol Modelling and Bio-aerosol Research), an atmospheric chamber facility recently designed and implemented at the Environmental Physics Laboratory of 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. Here we present the experimental setup and some protocols established to analyze Gram-positive and Gram-negative model bacteria, Bacillus Subtilis and Escherichia Coli respectively, focusing in particular on the use of Field Emission Scanning Electron Microscopy techniques.