Aeromonas spp. are generally found in aquatic environments, although they have also been isolated from both fresh and processed food. These Gram-negative, rod-shaped bacteria are mostly infective to poikilothermic animals, although they are also considered opportunistic pathogens of both aquatic and terrestrial homeotherms, and some species have been associated with gastrointestinal and extraintestinal septicemic infections in humans. Several cell-surface glucans have been shown to contribute to colonization and survival of Aeromonas pathogenic strains in different hosts, playing important roles in bacterial–host interactions related to pathogenesis These include lipopolysaccharide (LPS), capsule, α-glucan, and glycosylated polar and lateral flagella.
Prior to its attachment to the lipid-A-core-OS structure of LPS, before the whole complex is exported to the external side of the outer membrane, the O-antigen needs to be fully synthesized. O-antigen biosynthesis begins with the generation of the lipid-linked glycan intermediate undecaprenyl phosphate (UndP)  and, once generated, a sugar transfer reaction takes place. In this regard, A. piscicola AH-3 has been shown to use WecP to transfer N-acetyl-galactosamine . Following this reaction, the O-antigen unit is flipped across the bacterial inner membrane by the Wzx protein , and assembled on the periplasmic side of the inner membrane by the Wzy O-antigen polymerase . The O-antigen is elongated until it reaches the final polymer length, in a process regulated by the O-antigen chain length regulator Wzz . A. piscicolaAH-3 (O:34) has been shown to follow the Wzx/Wzy-dependent pathway for O-antigen assembly, as both wzy and wzx genes are found in the O-antigen gene cluster of this strain . Interestingly, although the first sugar of the O-antigen repeating unit seems to be determinant for the generation of glycosidic bonds , the Wzy enzyme of A. piscicola AH-3 (O:34) has been shown to be permissive with this first sugar at the non-reducing end .