Characterizing bacterial assemblages in sediments and aerosols at a dry lake bed in Australia using high-throughput sequencing

Dust storms are responsible for the transport of a large quantity of bacteria from arid regions. A severe drought in the first decade of the new millennium in Australia increased the incidence of dust transport further. The major aims of this study were to characterize the bacterial communities in aerosols and their associated source sediments using high-throughput sequencing (HTS) and to investigate the possibility of using HTS to link dust to its source, which has not been previously performed in this way. Four field campaigns were conducted at the recently evaporated saline playa Lake Gnarpurt in the Australian state of Victoria between 2008 and 2010 (3 in the austral summer, 1 in winter) to collect aerosol and sediment samples. Aerosol samples were collected on filters up to 150 m above the lake bed using a tethered helium-filled balloon. DNA was extracted from all samples using commercial kits, and the bacterial communities were examined using 454 HTS on the 16S rRNA gene. Over 200,000 sequences from 29 samples were analysed. In both sediment and aerosol samples, Salinimicrobium was the most abundant taxon; however, there was great variation and diversity across all samples. Analysis of similarities of the bacterial communities indicated that there was a significant overlap between the sediment samples and the aerosols collected above that location, showing that the bacteria in the air was derived from a subset of dust from a nearby source. The challenge remains to use bacterial profiling to link an aerosol sample to a distant source.