Isolation and Molecular Identification of Pathogenic Free-Living Amoebae from Environmental Samples in Tenerife, Canary Islands, Spain

Free-living amoebae (FLA) are protozoa that have been reported worldwide from various environmental sources. However, only some groups (Acanthamoeba spp., Naegleria fowleri, Balamuthia mandrillaris, Sappinia pedata, Vahlkampfia spp., and Vermamoeba vermiformis) are considered to be pathogenic for humans and other animals. FLA has been previously reported in the Canary Islands archipelago since 2005. However, climate change and other environmental factors that could affect the communities of FLA in the islands lead to the development of this extra study. This study was carried out in Tenerife, the largest and most populated island, between June 2021 and July 2022. A total of 28 soil samples and 23 water samples were seeded in 2% non-nutrient agar (NNA) plates, incubated at 26 °C, and monitored daily to evaluate the presence of FLA. DNA was extracted from those plates on which there was suspected FLA growth, and polymerase chain reaction amplification of the 18S rRNA gene (DF3• region on the case of Acanthamoeba) was carried out. The obtained results showed that the genus Acanthamoeba (25/51:48.07%), with the genotype T4 being the most common (21/25; 84%), and the species V. vermiformis (7/51; 13.73%) were the most abundant FLA in the surveyed samples collected from Tenerife.