The recently discovered comammox process encompasses both nitrification steps, the aerobic oxidation of ammonia and nitrite, in a single organism. All known comammox bacteria are affiliated with Nitrospira sublineage II and can be grouped into two distinct clades, referred to as A and B, based on ammonia monooxygenase phylogeny. In this study, we report high-quality draft genomes of two novel comammox Nitrospira from the terrestrial subsurface, representing one clade A and one clade B comammox organism. The two metagenome-assembled genomes were compared with other representatives of Nitrospira sublineage II, including both canonical and comammox Nitrospira. Phylogenomic analyses confirmed the affiliation of the two novel Nitrospira with comammox clades A and B respectively. Based on phylogenetic distance and pairwise average nucleotide identity values, both comammox Nitrospira were classified as novel species. Genomic comparison revealed high conservation of key metabolic features in sublineage II Nitrospira, including respiratory complexes I-V and the machineries for nitrite oxidation and carbon fixation via the reductive tricarboxylic acid cycle. In addition, the presence of the enzymatic repertoire for formate and hydrogen oxidation in the Rifle clades A and B comammox genomes, respectively, suggest a broader distribution of these metabolic features than previously anticipated.

The genomes of the aerobic methanotrophs "Methyloterricola oryzae" strain 73aT and Methylomagnum ishizawai strain 175 were sequenced. Both strains were isolated from rice plants. Methyloterricola oryzae strain 73aT represents the first isolate of rice paddy cluster I, and strain 175 is the second representative of the recently described genus Methylomagnum.

Genome sequences of Methylobacter luteus, Methylobacter whittenburyi, Methylosarcina fibrata, Methylomicrobium agile, and Methylovulum miyakonense were generated. The strains represent aerobic methanotrophs typically isolated from various terrestrial ecosystems.

Methylohalobius crimeensis strain 10Ki is a moderately halophilic aerobic methanotroph isolated from a hypersaline lake in the Crimean Peninsula, Ukraine. This organism has the highest salt tolerance of any cultured methanotroph. Here, we present a draft genome sequence of this bacterium.

The genome sequences of Methylobacter marinus A45, Methylobacter sp. strain BBA5.1, and Methylomarinum vadi IT-4 were obtained. These aerobic methanotrophs are typical members of coastal and hydrothermal vent marine ecosystems.