The genus Arthrobacter

Abstract

The genus Arthrobacter is a member of the family Micrococcaceae and compared to other genera of the family, it contains the highest number of species. The genus cannot be considered monophyletic because within the clade embracing all Arthrobacter species also members of other genera of the family are present. Based on quinone system and peptidoglycan structure, the genus Arthrobacter can be subdivided into two major groups. One group is characterized by a quinone system with monosaturated menaquinone [MK-8(H 2 and/or MK-9(H 2) and peptidoglycan type A3α. The second group contains completely unsaturated menaquinones (MK-8, MK-9, and/or MK-10) and peptidoglycan type A4α. Combining chemotaxonomic and 16S rRNA based data, the genus can be subdivided at least into 11 subgroups. The majority of established species has been isolated from soil and sediments, but some were recovered from clinical specimens, as well. Arthrobacters are heterotrophic bacteria that do not require fastidious growth conditions. Most of them are mesophilic with growth optima below 30 °C, but some strains isolated from cold environments (Arctica, Antarctica, glaciers) are psychrotolerant or even psychrophilic. Numerous arthrobacters have been studied that are able to degrade harmful compounds such as 4-chlorophenol, 4-fluorophenol, 4-nitrophenol, or phenanthrene. Some strains have been identified as a source of enzymes including cold-adapted β-galactosidases. Since the genus Sinomonas harbors three former Arthrobacter species, its species will be dealt with here without separating from Arthrobacter species.