Assessment of the Presence of Free-Living Amoebae in Soil Samples from the Northwest Region of Spain Using Culture and Molecular Assays

Free-living amoebae (FLA) such as <i>Acanthamoeba</i> spp., <i>Balamuthia mandrillaris</i>, <i>Naegleria fowleri</i>, <i>Sappinia</i> spp., <i>Vahlkampfia</i> spp., and <i>Vermamoeba vermiformis</i> are naturally widespread in the environment, causing rare but fatal and debilitating infections in humans. In the present study, a total of 87 soil samples were collected from four provinces in the autonomous community of Castilla y León, Spain. These samples were collected in three different seasons during 2022-2023 (t1-t3) and were analysed by culture and molecular techniques (conventional PCR/sanger sequencing and qPCR). The obtained data revealed that the genus <i>Acanthamoeba</i> and the species <i>Vermamoeba vermiformis</i> were the most prevalent FLA. Furthermore, other genera/species of FLA were identified in the tested soil sources, suggesting a rich microbial biodiversity in Castilla y León soils. In addition, this study provides an important basis for future research on the ecology of these organisms and their potential impact on public health and the environment.