# Methylocystis hydrogenophila sp. nov.—A Type IIa Methanotrophic Bacterium Able to Utilize Hydrogen as an Alternative Energy Source

## TL;DR

Scientists discovered a new methane-consuming bacterium that can also use hydrogen for energy and tolerate salt.

## Contribution

A new Methylocystis species is described with unique hydrogen utilization and osmoprotectant traits.

## Key findings

- Strain SC2T is a distinct Methylocystis species with unique genomic and physiological traits.
- The bacterium uses hydrogen as an alternative energy source and asparagine as an osmoprotectant.
- It possesses complete genetic pathways for nitrogen fixation, denitrification, and hydrogen oxidation.

## Abstract

A novel species of the genus Methylocystis is proposed based on polyphasic evidence from strain SC2T, isolated from the heavily polluted Saale River near Wichmar, Germany. Digital DNA–DNA hybridization and phylogenomic analyses demonstrate that strain SC2T represents a distinct species within the genus, clearly separated from its closest relatives, namely Methylocystis suflitae NLS-7T, Methylocystis rosea SV97T, Methylocystis silviterrae FST, and Methylocystis hirsuta CSC1T. As is typical of the family Methylocystaceae, cells possess intracytoplasmic membranes arranged parallel to the cytoplasmic membrane, and the dominant fatty acids are C18:1ω8c and C18:1ω7c. The strain grows aerobically on methane as the primary carbon and energy source and expresses both low- and high-affinity particulate methane monooxygenase (pMMO), but lacks the soluble form. The species epithet reflects the strain’s ability to utilize hydrogen as an alternative energy source. A further feature is its use of asparagine as an osmoprotectant, enhancing salt tolerance. Genomic analysis reveals complete pathways for nitrogen fixation, denitrification, and hydrogen oxidation. These genetic and physiological characteristics support the designation of a novel species, for which the name Methylocystis hydrogenophila sp. nov. is proposed. The type strain is SC2T (=DSM 114506 = NCIMB 15437).