Metabacillus

All members of the genus Metabacillus are aerobic and demonstrates endospore formation. These bacteria can be found in a wide range of environments, from hypersaline lakes, coastal marine regions and soil. While some species are non-motile, most Metabacillus species are motile. Some species are moderately salt tolerant and able to live in saline environments such as coastal regions. Metabacillus can survive in temperatures ranging 4–45 °C (39–113 °F), but optimal growth occurs in the range of 25–37 °C (77–99 °F).

Six conserved signature indels (CSIs) have been identified as specific for Metabacillus species in proteins such as 3-phosphoshikimate-1-carboxyvinyltransferase, fibronectin/fibrinogen-binding protein, spore protease YyaC, and DEAD/DEAH box helicase.[1] These CSIs were identified through the analysis of genome sequences from Metabacillus species and provide a reliable means to distinguish Metabacillus from other Bacillaceae genera in molecular terms.

As of May 2021, there are a total of 15 species with validly published names in the genus Metabacillus.[9] Members of this genus group together and forms a monophyletic branch in phylogenetic trees created from concatenated sequences from various datasets of conserved proteins.[1] This monophyletic clade is also found in the Genome Taxonomy Database (GTDB).[10]

Additional phylogenetic studies have identified the species Bacillus weihaiensis as a member of Metabacillus based on taxonomic placement in phylogenetic trees as well as shared molecular markers (specifically conserved signature indels) with other members of Metabacillus.[8] However, transfer was not proposed due to the lack of strain culture information. As Bacillus continues to be a fast growing genus with the frequent addition of novel species and sequenced genomes, it would be necessary to continually update and validate previous classification proposals.