ABSTRACT
The current genus Rhodopirellula consists of marine bacteria which belong to the family Pirellulaceae of the phylum Planctomycetota. Members of the genus Rhodopirellula are aerobic, mesophiles and chemoheterotrophs. The here conducted analysis built on 16S rRNA gene sequence and multi-locus sequence analysis based phylogenomic trees suggested that the genus is subdivided into four clades. Existing Rhodopirellula species were studied extensively based on phenotypic, genomic and chemotaxonomic parameters. The heterogeneity was further confirmed by overall genome-related indices (OGRI) including digital DNA-DNA hybridization (dDDH), average nucleotide identity (ANI), average amino acid identity (AAI), and percentage of conserved proteins (POCP). AAI and POCP values between the clades of the genus Rhodopirellula were 62.2-69.6% and 49.5-62.5%, respectively. Comparative genomic approaches like pan-genome analysis and conserved signature indels (CSIs) also support the division of the clades. The genomic incoherence of the members of the genus is further supported by variations in phenotypic characteristics. Thus, with the here applied integrated comparative genomic and polyphasic approaches, we propose the reclassification of the genus Rhodopirellula to three new genera: Aporhodopirellula gen. nov., Allorhodopirellula gen. nov., and Neorhodopirellula gen. nov.
Subject(s)
Bacteria , DNA , Sequence Analysis, DNA , RNA, Ribosomal, 16S/genetics , Phylogeny , Bacteria/genetics , DNA, Bacterial/genetics , Bacterial Typing Techniques , Fatty Acids/chemistryABSTRACT
Cyanobacterial strain PS4G was isolated from seepage soil sampled at Pachmarhi, Madhya Pradesh, India, and was characterized using a polyphasic approach. The results of morphological analysis showed that strain PS4G had unique morphological characteristics which were not observed in the other described species of the genus Fortiea. In the 16S rRNA gene phylogenetic analysis inferred using Bayesian inference, maximum-likelihood and neighbour-joining methods, strain PS4G clustered within the clade consisting of the members of the genus Fortiea. Furthermore, in the secondary structure analysis using the D1-D1' helix and BoxB regions of 16S-23S ITS, strain PS4G showed marked differences in comparison with other members of the genus Fortiea. Overall, the morphological, phylogenetic and folded 16S-23S ITS secondary structure examination indicated that strain PS4G represents a novel species of the genus Fortiea. In accordance with the International Code of Nomenclature of Algae, Fungi and Plants we describe a novel species of Fortiea with the name Fortiea necridiiformans sp. nov.
