Bacteria responsible for stomach upset associated with seafood can rest and “wake up”

Scientists have discovered how bacteria that are normally responsible for seafood-related stomach upsets can fall asleep and then “wake up”.

Vibrio parahaemolyticus is a marine bacterium that can cause gastroenteritis in humans when eaten in raw shellfish or undercooked as oysters and mussels.

Some of these bacteria can remain dormant in poor growing conditions such as cold temperatures – and can remain in that state of hibernation for long periods before reappearing.

Scientists at the University of Exeter have identified a population of these dormant cells that are better at arousal, and have discovered an enzyme involved in that awakening process.

“Most of these bacteria die when exposed to poor growth conditions, but we have identified subpopulations of bacteria that can survive for a long time,” said lead author Dr Sariqa Wagley , from the University of Exeter.

“We have found that this population has a better capacity to regenerate when conditions improve.

“Our tests show that, when these temporary bacteria are regenerated they are just as strong and capable of causing disease.”

The decisions could have an impact on seafood safety, as dorm cells are not available using routine microbiological screening tests and the actual bacterial load (bacterial size) could be reduced. reduction.

When they fall asleep, these bacteria change shape, reduce respiratory activity and do not grow as healthy bacteria on agar plates used in routine laboratory tests, so they are much harder to find. Using a range of tools, we were able to detect temporary bacteria in seafood samples and laboratory cultures and look at their genetic content to see how they might survive for long periods. It is important to remember that deep cooking kills bacteria in seafood. Our results may help us predict the conditions in which dorm bacteria need to regenerate. “

Dr Sariqa Wagley, Principal study author, University of Exeter

Working with the seafood industry, the Exeter team identified an enzyme lactate dehydrogenase that breaks down lactic acid into pyruvate, a key component of several metabolic pathways (chemical reactions in a cell).

The findings suggest that lactate dehydrogenase is essential both for maintaining bacterial sleep and recovery back to active form.

Vibrio parahaemolyticus usually grows in warm, tropical marine environments, although Dr Wagley said it is now common in UK waters during the summer months due to rising sea temperatures in the last few years.

During the winter, it is not found in the marine environment across the UK and is thought to die due to the cold winter temperatures.

This study could explain how Vibrio parahaemolyticus is able to re-enter the environment during the summer.

The study was partly funded by the Biotechnology and Biological Sciences Research Council (BBSRC), with additional funding and support from Lyons Seafoods.

The paper, published in the journal Pathogens PLOS, titled: “Bacterial secretion: undergrowth of functional but non – cultured cells indicates improved fitness for regeneration.”