Capsular polysaccharide from Psychrobacter sp. TAE2020: An unusual amino sugar-enriched macromolecule with anti-biofilm and emulsification activities

Extracellular polysaccharides exhibit a broad range of biological activities, among which antibiofilm activity is of particular interest due to the growing clinical importance of biofilm-related infections. Psychrobacter sp. TAE2020, a marine Gram-negative bacterium, produces a molecular complex named CATASAN, endowed with antibiofilm properties. The aim of this study is the identification and structural characterisation of the polysaccharidic component of the CATASAN complex. Moreover, the interest was in finding the structural features possibly responsible for the anti-biofilm and emulsifying activities. Here, it has been demonstrated that the polysaccharide within the CATASAN complex corresponds to the capsular polysaccharide produced by Psychrobacter sp. TAE2020. The detailed primary structure of this CPS is here reported, which is composed of a tetrasaccharide repeating unit containing two residues of α-D-galactosamine, one residue of α-D-2,4-diacetamido-2,4,6-trideoxy-α-glucopyranose, and the unusual α-L-gulosamine. The physical properties of the CPS, such as its ability to adhere to hydrophobic surfaces and exhibit emulsifying activity, suggest that this polymer is a promising candidate for alternative anti-infective applications in clinical settings.