Register list for 16 new names including Kaelpiales ord. nov.

This class belongs to the phylum Omnitrophota. All previously visualized cells belonging to this class were small, and of approximately 0.2 µm. In serial-filtration experiments, most organisms were retained by filters with pore sizes at or below 0.2 µm. Genes encoding the tight-adherence complex were largely conserved, and most taxa have predicted capacity for acetogenesis through the bacterial Wood-Ljungdahl pathway. Additionally, group 4g hydrogenases were primarily observed in this class. Very large ORFs are pervasive throughout this class. Genome assemblies belonging to this class originate from lake or river water, groundwater, geothermal springs, wastewater, saline and freshwater sediment, bulk soil, and other engineered environments. The nomenclatural type for the class is the genus Velaminicoccus Kizina et al. 2022.

This class belongs to the phylum Omnitrophota. Observed cell size vary greatly within the class, and cells of 0.2 µm to 2.5 µm have been observed. Sequence data of organisms belonging to the class is also frequently observed from larger cell fractions during serial-filtration experiments. Most members of the class lack several genes associated with parasitism and predation, like those encoding tight-adherence complexes and ATP/ADP translocases, suggesting that most may primarily be free-living. Predicted capacity for acetogenesis through the bacterial Wood-Ljungdahl pathway predominates in the class. Only group 4g hydrogenases are found within members of the class. Several members encode very large ORFs. Genome assemblies belonging to this class originate from a variety of environments, including river or lake water, groundwater, wastewater, saline water, geothermal springs, saline and aquatic sediments, and soil. The type for the class is the genus Gorgyraea Williams et al. 2021. 

This order belongs to the class Velaminicoccia in the phylum Omnitrophota. Available cell size data indicate likely conservation of small cell sizes within the order. In contrast to other members of the class, the genomes belonging to this order encode diverse respiratory pathways and generally lack all genes associated with acetogenesis and the Wood-Ljungdahl pathway. Components for tight-adherence complexes and the very large ORFs are encoded by most genomes belonging to this order. Assemblies originated from water (including groundwater, wastewater and geothermal springs), soil, sediment and engineered environments. Environmental samples from which assemblies were derived were taken in the presence of oxygen at circumneutral to slightly basic pH. The type for this order is the genus Zapsychrus.

The taxonomic placement of this order is uncertain in the phylum Omnitrophota. This is a monotypic order and its description is currently the same as for its nomenclatural type, the genus Kaelpia Williams et al., 2021.

This order belongs to the class Velaminicoccia, in the phylum Omnitrophota. Members of the order with available cell size data are < 0.3 µm. High-quality genomes of members of the order encode very large ORFs, components of tight-adherence complexes, and genes consistent with an acetogenic metabolism. Assemblies belonging to this order originate from lake and groundwater, as well as wastewater. The nomenclatural type for the order is the genus Velaminicoccus.

This order belongs to the class Velaminicoccia, phylum Omnitrophota. Where data is available for putative cell sizes, the cells are below 0.3 µm. Very large ORFs are prevalent in the genomes belonging to this order. Most genomes code for tight-adherence complexes. Predicted energy metabolism in the order is acetogenesis through the Wood-Ljungdahl pathway. Members belonging to this order have been enriched for in a anaerobic bioreactor community grown on propionate at high dilution rate. Assemblies identified as belonging to this order originated from all environments reported for the class Velaminicoccia. Where available, samples from which assemblies were derived were collected at low oxygen concentrations or anaerobic conditions, at temperatures ranging from 10 °C to 40 °C, and at slightly acidic (pH 6) to slightly basic (pH 8.5) conditions. Most genomes belonging to this order possess a Group A [FeFe] and/or a Group 4g [NiFe] hydrogenase. The nomenclatural type of the order is the genus Gygaella.

This order belongs to the class Gorgyraia, in the phylum Omnitrophota. Where available, cells of organisms belonging to the order are small (<0.3 µm). Very large ORFs is present in some members of the order, but are not pervasive within the order. Environmental samples from which assemblies are derived range in pH from acidic to circumneutral. The nomenclatural type of the order is the genus Tantalella.

This order belongs to the class Gorgyraia, in the phylum Omnitrophota. As a monotypic order, the description for the order is currently the same as for the genus Gorgyraea, the nomenclatural type for the order.

This family belongs to the order Zapsychrales, in the class Velaminicoccia, phylum Omnitrophota. Most assemblies within this family encode very large ORFs. Genomes in this family are derived from samples of soil, ground- and wastewater, geothermal springs and engineered environments. When reported samples were typically taken at circumneutral pH, microaerobic conditions and temperatures between 10 °C and 30 °C. The nomenclatural type for the family is the genus Zapsychrus.

This family belongs to the order Kaelpiales, but their taxonomic placement at the class-level within the Omnitrophota is uncertain. The nomenclatural type for the family is the genus Kaelpia.

This family belongs to the order Gorgyraeales, class Gorgyraia, phylum Omnitrophota. As a monotypic family, the description of the family is currently the same as for the genus Gorgyraea, the nomenclatural type for the family.

This family belongs to the order Gygaellales, class Velaminicoccia, phylum Omnitrophota. The available genome assembly belonging to this family was recovered from Ace Lake, Antarctica. The nomenclatural type for the family is the genus Gygaella.

This family belongs to the order Tantalellales, class Gorgyraia, phylum Omnitrophota. The only observed cell size within the family is that of cells SKK-01, at 2.5 µm.  Very large ORFs are intermittently encoded by genomes in this family. Parasitism and predation-related genes are largely absent from this family, and some genes linked to acetogenic metabolism is present in genomes belonging to the family. Members of this family has been recovered from saline water and sediment, and freshwater and lake sediment. The nomenclatural type for the family is the genus Tantalella Williams et al. 2021.

This family belongs to the order Velaminicoccales, class Velaminicoccia, phylum Omnitrophota. When known, cells are small (< 0.3 µm). Very large ORFS, or genomic scaffolds homologous to very large ORFs are found in all genomes in the family. Most genomes encode tight-adherence complexes and genes for acetogenesis through the bacterial Wood-Ljungdahl pathway. Assemblies assigned to the family have been recovered from ground- and wastewater. The nomenclatural type for the family is the genus Velaminicoccus.

This family belongs to the order Zapsychrales, class Velaminicoccia, phylum Omnitrophota. As only a single genus is known for this family, the description of the family is currently still the same as for its nomenclatural type, Aceula.

This species conservatively belongs to the genus Zapsychrus. Low AAI values, typically associated with family-level relationships are observed between this taxon and the nomenclatural type for the genus, however, relative evolutionary divergence based on a phylogenomic tree inferred from the condensed Bac120 marker set indicate likely genus-level relationships. In addition to characteristics provided for the genus, predicted genome sizes range between 2.2-2.7 Mb with %GC between 37.12 and 37.60%. Some genes associated with acetogenesis and an Rnf complex are encoded by the genome. A reversible acetyl-CoA synthetase coupled with a cytoplasmic Group A3 [FeFe] hydrogenase encoded by this species may facilitate acetogenesis. A respiratory F-type ATPase, and a conductive pilin are encoded by genomes of this species. All genes associated with the tight-adherence complex formation and Type-4a pilus production are present in the genomes. Additionally, a "symbiotic" F-type ATPase and very large ORF are present in the genomes. Assemblies for this species originated from soil and groundwater samples from Rifle, Colorado, USA, where a pH of 7.67 was reported for some samples. The nomenclatural type for the species is the genome GCA_001805965.1.