Arthrobacter arilaitensis

Taxonomy

The genus Arthrobacter belongs to the Actinobacteria class, the Actinobacteridae subclass, the Actinomycetales order, the Micrococcineae suborder, and the Micrococcaceae family. It is constituted of Gram-positive non-spore forming bacteria, which are aerobic, catalase-positive, and sometimes motile. The cells form irregular rods or cocci, depending on their growth phase. Two groups can be distinguished in function of their peptidoglycan structure: species with A3 alpha and species with A4 alpha peptidoglycan. The Arthrobacter arilaitensis species has been described by Irlinger at al. in 2005 ( [1]). It has an A4 alpha peptidoglycan and phylogenic analyses based on 16S RNA genes showed that it is related to the Arthrobacter nicotianae group.

Habitat and activity in cheeses

Numerous species of bacteria and yeasts are present at the surface of smear-ripened cheese such as Livarot, Maroilles and Munster. Their concentration reaches up to 1010 cells per gram of cheese. This microflora has a significant effect on the organoleptic properties of the cheeses (flavour, colour, texture). Presence of Arthrobacter species in cheeses has been reported for a long time, especially in smear-ripened cheeses ( [2] [3] [4] [5]). Several studies showed that most of the Arthrobacter isolates originating from cheeses belong to the Arthrobacter arilaitensis species ( [6] [7]). Their function in cheese ripening has now been well established.