Bacteria population soars when temperatures increase
Rising water temperatures have made it more likely for potentially pathogenic bacteria to make an appearance in the North and Baltic Seas. The proliferation of pathogenic bacteria is caused by summer heatwaves in the vicinity. They comprise bacteria from the genus Vibrios, which can cause diarrhoeal illness and severe inflammations.
Now, researchers have discovered that such bacteria may have the ability to survive on microplastic particles. The findings of their research have recently been published in the Marine Environmental Research journal.
Dr Gunnar Gerdts, a microbiologist at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research on Helgoland called them climate-change winners because their population increases during heatwaves, especially when the temperature is above 22 degrees Celsius. This is especially so in the coastal areas of the Baltic Sea, where heatwaves have been associated with illnesses or deaths caused by the bacterium Vibrio vulnificus.
Dr Gerdts and his team examined samples from the ocean to determine whether the bacteria can derive any benefit from the plastisphere. This is the thin layer of biofilm on the surface of plastic particles where bacteria, fungi and microalgae can be found. The composition of the biofilm depends on the condition of the plastic surface and the types of organisms in the surrounding water. Through gene sequencing, it is suggested that Vibrios may also be found within this ecosystem.
Through their research, the researchers have proved for the first time the existence of the Vibrio species in the biofilms on microplastic particles. During an expedition, they took samples from 62 sampling stations in the North and Baltic Seas. In addition, a Neuston catamaran was used to skim off microplastic particles directly below the water surface. Of the 185 samples collected, evidence of Vibrios was found on 19 of them, mostly in samples from the same sampling stations.
“This illustrates the potential of pathogens hitchhiking on these particles, i.e. disseminating as free-loaders within an ecosystem and proliferating beyond,” said Gerdts. His research, however, did not yield any evidence of pathogenic genotypes.
He is in contact with the authorities on this topic. “At the North and Baltic Sea coasts, regional investigation offices already spot-check water samples for Vibrios species. It would be a cause for concern if microplastic particles ‘charged’ with Vibrios became a regular occurrence in the future, as biofilms generally have a higher bacterial density than open water,” he said.
Link to study: www.sciencedirect.com/.../S014111361630112X