Companilactobacillus (Com.pani.lac.to.ba.cil’lus. M. L. n. companio friend, partner; N.L. masc. n. Lactobacillus a bacterial genus; N.L. masc. n.; Companilactobacillus, Companion-lactobacillus, the name refers to the association of Companilactobacillus species with other lactobacilli, particularly heterofermentative organisms, in cereal and vegetable fermentations [114]).

Companilactobacillus species are Gram-positive, homofermentative and non-spore-forming rods. Strains of Companilactobacillus were isolated from fermented vegetables, particularly fermented mustard or onion greens, and fruits (17 type strains; five of these from mustard or onion fermentations), sourdough or related cereal fermentations (7 type strains), sausages or meat (seven type strains) or other plant sources; one isolates was obtained from a fermented dairy product. Companilactobacillus appears not to be dominant in any of these fermentations but occurs consistently (type I sourdoughs and fermented mustard or onion greens) or occasionally (meat, salami). Companilactobacillus metriopterae was isolated from a grasshopper and forms and outgroup that differs with respect to genome size (C. metriopterae 1.50 Mbp; other species range from 2.17 to 2.9 Mbp); mol% G+C content of DNA (C. metriopterae 32.8; other species range from 34.1 to 38.6) and physiological properties. The temperature requirements for growth are inconsistent; all strains grow between 25 and 30 °C, most but not all species grow at 15 °C and some species grow at 45 °C. The fermentation of pentoses by Companilactobacillus is species- or strain-specific. Information on the ecology or lifestyle of companilactobacilli is scarce.

A phylogenetic tree on the basis of 16S rRNA genes of all species in the genus Companilactobacillus is provided in Fig. S6C.

The type species is Companilactobacillus alimentarius comb. nov.; Companilactobacillus was previously referred to as L. alimentarius group.