For their study, Doitsidou and her colleagues used a nematode worm model that scientists had genetically engineered to express a human version of the alpha-synuclein protein.
These worms normally develop aggregates, or clumps, of alpha-synuclein at day 1 of their adulthood, which is 72 hours after they hatch.
However, when the researchers fed worms a diet containing a probiotic bacterial strain called Bacillus subtilis PXN21, they observed “a nearly complete absence of aggregates,” as they state in their paper. The worms still produced the alpha-synuclein protein, but it did not aggregate in the same way.
In worms that had already developed protein aggregates, switching their diet to B. subtilis cleared the aggregates from the affected cells.
The team then followed a set of worms through their lifespan and compared a B. subtilis diet with a conventional laboratory diet.
“The maximum number of aggregates reached in animals fed with B. subtilis was far lower than that observed on the [standard] diet, indicating that B. subtilis does not simply delay aggregate formation,” the authors explain in the paper.
“B. subtilis PXN21 inhibits and reverses [alpha-synuclein] aggregation in a [roundworm] model,” they note.
Is this effect specific for B. subtilis PXN21, though? To answer this question, the team compared a number of different strains of the bacterium and found that they had similar effects.