A novel phytoplasma, designated strain SoyST1c1, associated with a newly emerging disease in soybean (Glycine max), known as soybean stunt (SoyST), was found in 2002 in a soybean plantation in Alajuela Province, Costa Rica. The same phytoplasma, or a very closely related strain, also infected sweet pepper (Capsicum annuum) with purple vein syndrome (SwPPV) and passion fruit vine (Passiflora edulis) with bud proliferation disease (PasFBP) in the same region. Sequence analysis of cloned 16S rRNA gene sequences (GenBank accession nos FJ226068–FJ226073 and HQ225624–HQ225635) indicated that all three affected plants were infected by phytoplasmas that shared <97.5 % sequence similarity with previously described phytoplasmas. The SoyST-causing phytoplasma represents a new taxon, most closely related to phytoplasma group 16SrI and 16SrXII strains. Virtual RFLP analysis indicated that the SoyST-causing phytoplasma and its closely related strains represent a novel 16Sr group, designated 16SrXXXI. Phylogenetic analysis of 16S rRNA gene sequences from the new phytoplasma strains, those previously described as ‘Candidatus Phytoplasma spp.’ and other distinct, as yet unnamed, phytoplasmas indicated that the SoyST-causing phytoplasma represents a distinct lineage within the aster yellows/stolbur branch on the phylogenetic tree. On the basis of its unique 16S rRNA gene sequence and biological properties, strain SoyST1c1 represents a novel taxon, for which the name ‘Candidatus Phytoplasma costaricanum’ is proposed with SoyST1c1 as the reference strain.
As part of a study of the diversity of planctomycetes, two novel strains, designated OJF2T and OJF8, were isolated from the sediments of a freshwater aquarium. The organisms were chemoheterotrophic, spherical and pink-pigmented, had an optimum growth temperature of about 30–35 °C and an optimum pH for growth of around 7.5–8.5. The predominant fatty acids were C18 : 1ω9c and C16 : 0. The two strains were able to assimilate several sugars and organic acids. 16S rRNA gene sequence analysis confirmed the affiliation of these organisms to the phylum ‘Planctomycetes’; they showed highest similarity to the type strains of Singulisphaera acidiphila (92.4 %) and Isosphaera pallida (91.9 %). On the basis of physiological, biochemical and chemotaxonomic characteristics, strains OJF2T and OJF8 are considered to represent a novel species of a new genus of the order Planctomycetales, for which the name Aquisphaera giovannonii gen. nov., sp. nov. is proposed. The type strain of Aquisphaera giovannonii is OJF2T ( = CECT 7510T = DSM 22561T).
Caves have generally been found to host phototrophic micro-organisms from various taxonomic groups, with cyanobacteria comprising an important group that have adapted to these stable and highly specific environments. A polyphasic study based on aspects of classical morphology and molecular data revealed two new monospecific genera from fresh material of Greek and Spanish caves. Both taxa are characterized by obligatory true branching (T-type, V-type and false branching), the presence of heterocysts, and reproduction by hormocysts and akinetes. They shared some similarities in their morphological characteristics as revealed by light, scanning electron and transmission electron microscopy, but phylogenetic analysis based on 16S rRNA gene sequences showed that the two phylotypes were different (89.8 % similarity); this represents an example of shared morphology in genetically different strains of cave-adapted species. Phenotypic and genetic traits strongly support classification of the phylotypes as independent taxa in the order Stigonematales (the most differentiated and complicated group of cyanobacteria), family Loriellaceae Geitl 1925. Hence, the names Iphinoe spelaeobios Lamprinou and Pantazidou gen. nov., sp. nov. and Loriellopsis cavernicola Hernández-Mariné and Canals gen. nov., sp. nov. are proposed.