Dust in the air can carry bacteria thousands of kilometers.


On September 29, 2011, dust from the Arabian Peninsula drifted across the eastern portion of the Mediterranean Sea, perhaps carrying bacteria. Credit: MODIS Rapid Response Team, Jeff Schmaltz, NASA GSFC

Attached bacteria travel with the dust as breezes pick it up from the ground. Aerobiomes are made up of these airborne bacteria, and as the dust settles once more, they have the potential to change the chemistry of the environment and impact both human and animal health, though scientists are unsure exactly how.

Daniella Gat and colleagues recently collected airborne dust in Rehovot, Israel, for a study that was published in the Journal of Geophysical Research: Biogeosciences. While trajectory modeling identified the bacterial community composition in the dust, DNA sequencing allowed the researchers to determine its origins. It was discovered by the researchers that dust from various regions, such as North Africa, Saudi Arabia, and Syria, may transport varied bacterial communities from hundreds to thousands of kilometers away.

The researchers compared Israel's aerobiomes to bacterial communities found on plant leaf surfaces, in Israeli soils, in seawater from the Mediterranean and Red Seas, and in dust collected in Saudi Arabia close to the Red Sea's shoreline in order to determine where the bacteria in Israel's aerobiomes originate. The most similar aerobiomes found in Israel were those found in Saudi Arabia, indicating that a sizeable portion of the bacteria in Israeli air—roughly 33%—can originate from distant places.

In Israel, bacterial populations on the ground exhibited less similarity to aerobiomes. However, 34% of Israel's aerobiome bacteria on average most likely originated from Israeli soils, demonstrating that soil and aerobiomes can trade a sizable number of bacteria. Plant surfaces (11%) and water from the Mediterranean and Red Seas (0.9%) made up a smaller portion of the aerobiome's bacterial population.

The researchers compared the bacterial genes found in airborne dust in Israel with those of the communities from the other analyzed locations because understanding how aerobiomes could impact ecosystems and health depends on knowing what genes they contain. In comparison to bacteria in soil, saltwater, or plant surfaces, they discovered that the bacteria in dust had higher concentrations of genes that biodegrade organic pollutants like benzoate and impart antibiotic resistance.

Higher percentages of these genes reflect widespread anthropogenic influences on the structure and function of the aerobiome community, according to the researchers.

The researchers believe that dust-driven spread of antibiotic resistance genes may have an impact on human and cattle health, but site-specific investigations are required to determine whether dust actually introduces novel antibiotic resistance to a specific area. Furthermore, dust-borne antibiotic-resistant bacteria might not be alive. In order to verify this, the researchers propose to search for bacterial RNA, which would represent living bacteria cells, in dust samples.

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