Researchers from the Max Planck Institute have found out more about how vibrio spreads in the environment.
Vibrio parahaemolyticus causes acute gastroenteritis in humans and is the leading cause for seafood borne illnesses in the world.
Scientists from the Max Planck Institute for Terrestrial Microbiology in Marburg, Germany, identified specialized adventurer cells that ensure the bacterium’s dissemination and prevalence. Findings are published in the ISME Journal. They could help manage the disease in the future.
In Central and Northern Europe, Vibrio infections are among emerging diseases whose incidence has recently increased or is likely to rise in the future. Reasons for this are global trade and the higher water temperatures caused by climate change.
Mussels, oysters and crabs in supermarkets from tropical regions are possibly highly contaminated all year round. They can cause infection if eaten raw or are insufficiently cooked.
Vibrio parahaemolyticus forms colonies in the tidal zone of estuarine areas and its lifecycle is triggered by conditions in this habitat. Scientists simulated conditions of the tidal zone and investigated the bacterial lifecycle and mechanisms of movement.
“In order to develop any measures against the spread of Vibrio parahaemolyticus and related bacteria, we must first understand the structure and distribution strategy of the bacterial colonies,” said Simon Ringgaard of the Max Planck Institute for Terrestrial Microbiology.
Vibrio parahaemolyticus forms special cell types in different environmental conditions. While short swimmer cells with a single polar flagellum can move quickly in a liquid environment, the longer swarm cells reside within bacterial populations that are attached to solid surfaces. Swarmer cells are specialized for movement over surfaces and can rapidly colonize new surface areas.
The Vibrio bacterial swarm colonies are different. While the middle of the colony consists of rather shorter cells, the longer swarm cells are found in the outer areas.
New cell length
Researchers showed that if the swarm colony is flooded with water, like the natural habitat during tidal rhythms, cells are released from the colony into the liquid surroundings. However, the released cells are an unexpected and new cell type of medium length. These adventurer cells are optimized for living in water and are good swimmers.
The team found that once released, the adventurer cells were capable of spreading in their new liquid environments and were able to smell and move towards potential nutrient sources such as chitin – an essential component of marine animals to which Vibrio parahaemolyticus attaches.
So the release of adventurer cells into the water could help spread the bacterium in the environment and bring Vibrio parahaemolyticus to new shores such as the surface of seafood and into the food chain, increasing the risk of infection.
Researchers investigated the lifecycle as a function of environmental conditions and time and found characteristic expression patterns that could be used for future detection of the bacterium.
“Our experiments show that the colony always has a sub-population of adventurer cells that are ready to be released immediately upon flooding. Adventurer cells would thus be of central importance for the worldwide epidemiology of the disease and thus also for measures to contain it, for example in industrial aquaculture,” said Ringgaard.
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