ABSTRACT
An amoeba strain was isolated from marine sediment taken from the beach near a fumarole in Italy. The trophozoites of this new marine species transforms into flagellates with variable numbers of flagella, from 2 to 10. The strain forms round to oval cysts. This thermophilic amoeboflagellate grows at temperatures up to 54°C. Molecular phylogenetic analysis of the small subunit ribosomal DNA (SSU rDNA) places the amoeboflagellate in the Heterolobosea. The closest relatives are Stachyamoeba sp. ATCC50324, a strain isolated from an ocean sample, and Vrihiamoeba italica, a recent isolate from a rice field. Like some other heterolobosean species, this new isolate has a group I intron in the SSU rDNA. Because of the unique place in the molecular phylogenetic tree, and because there is no species found in the literature with similar morphological and physiological characteristics, this isolate is considered to be a new genus and a new species, Oramoeba fumarolia gen. nov., sp. nov.
Subject(s)
Amoeba/classification , Amoeba/growth & development , Geologic Sediments/parasitology , Amoeba/cytology , Amoeba/isolation & purification , Cluster Analysis , DNA, Protozoan/chemistry , DNA, Protozoan/genetics , DNA, Ribosomal/chemistry , DNA, Ribosomal/genetics , Flagella/ultrastructure , Genes, rRNA , Hot Temperature , Italy , Microscopy , Molecular Sequence Data , Phylogeny , RNA, Protozoan/genetics , RNA, Ribosomal/genetics , Sequence Analysis, DNA , Spores, Protozoan/cytologyABSTRACT
Tetramitus thermacidophilus n. sp. is a novel thermophilic and acidophilic amoeboflagellate isolated from acidic hot springs in the Caldera Uzon (Kamchatka, Russia) and in Pisciarelli Solfatara (Naples, Italy). We describe it based on physiological, morphological, and sequence data. It was grown in monoxenic culture on the archaeon Acidianus brierleyi as food. Tetramitus thermacidophilus multiplies in a pH range from 1.2 to 5 and in a temperature range from 28 °C to 54 °C. The shortest doubling time was 4.5 h at pH 3 at 45 °C. Its spindle-shaped biflagellated stage was only rarely found in culture. The amoeboid stage shows the typical locomotive form of vahlkampfiid amoebae. Sequence comparisons of the internal transcribed spacer sequences and the small subunit rRNA genes confirm that T. thermacidophilus is a novel species within the genus Tetramitus and that both isolates belong to that species.
