SNCA and Parkinson disease: Interestingly, a recent study on 20 patients with PD and 20 healthy controls found that the gut microbiota of PD had significantly higher levels of Desulfovibrio, a hydrogen sulfide producing hydrogenotrophic bacteria, the authors speculating that the LPS, hydrogen sulfide and magnetite produced by the strains of the Desulfovibrio bacteria could trigger alpha-synuclein conformational changes and aggregation [82].