The description is based on Inoue et al. (2000), Kämpfer et al. (2005), Peng et al. (2009), Madhaiyan et al. (2010) [26], [31], [35], [42] and this study. Cells are straight rods, 0.5–1.2 μm × 1.0–3.5 μm, motile by peritrichous flagella. Gram negative. Facultatively anaerobic. Optimum temperature for growth is 28–30 °C, but grows at 40 °C. Colonies are white to beige, round, convex and smooth with entire margins on tryptone soya agar. Some strains of Kosakonia cowanii may be yellow-pigmented. Positive for Voges-Proskauer. Generally positive for arginine dihydrolase and negative for lysine decarboxylase. Negative for gelatinase and indole. Reaction to ornithine decarboxylase is variable. Nitrate is reduced to nitrite. Glucose is fermented with production of acid and gas. Tweens 40 and 80, N-acetyl-d-glucosamine, l-arabinose, d-cellobiose, d-fructose, d-galactose, gentiobiose, d-glucose, lactose, maltose, d-mannitol, d-mannose, l-rhamnose, d-sorbitol, sucrose, d-trehalose, succinic acid mono-methyl ester, cis-aconitic acid, d-gluconic acid, d-saccharic acid, glycerol, α-d-glucose-1-phosphate, d-glucose-6-phosphate are oxidized (Biolog), whereas p-hydroxy-phenylacetic acid, itaconic acid, propionic acid, l-threonine, 2-aminoethanol and 2,3-butanediol are not. Reactions to N-acetyl-d-galactosamine, d-arabitol, m-inositol, d-melibiose, d-raffinose, turanose, l-alaninamide, l-proline and d-serine are variable. Major fatty acids are C16:0 and C18:1ω7c. C17:0 cyclo and summed features 2 (iso-C16:1 and/or C14:0 3-OH) and 3 (C16:1 ω7c and/or iso-C15:0 2-OH) can also be present in high amounts. Members of the genus Kosakonia form a clade using MLSA based on concatenated partial gyrB, rpoB, infB and atpD sequences.

Kosakonia species are isolated from clinical samples and environmental sources including soil and trees. Several species promote plant growth by fixing nitrogen

The type species is Kosakonia cowanii Inoue, Sugiyama, Kosako, Sakazaki and Yamai (2000).