This study examined biochemical and physiological characteristics of several bacterial isolates that produce gellan-related polysaccharides. Although originally classified into diverse genera including Pseudomonas, Alcaligenes, Azotobacter, and Xanthobacter, comprehensive analysis revealed these bacteria are closely related to each other and to Sphingomonas paucimobilis. The researchers evaluated carbon source utilization patterns using MicroLog testing, analyzed fatty acid profiles, examined pigment absorption spectra, and assessed additional biochemical properties including catalase, oxidase, and aesculin hydrolysis reactions. All sphingan-producing strains shared similar metabolic fingerprints, fatty acid compositions dominated by cis-vaccenic acid, and distinctive pigment absorption spectra. They displayed consistent patterns of antibiotic resistance, growth characteristics on specialized media, and sugar utilization. The study supports reclassification of gellan-producing bacteria into the genus Sphingomonas and introduces the term 'sphingans' for these gellan-related polysaccharides. The findings suggest polysaccharide production is more common in Sphingomonas than previously recognized and have implications for biotechnology applications and human health considerations.

Key findings

• Multiple bacterial isolates originally classified into different genera (Pseudomonas, Alcaligenes, Azotobacter, Xanthobacter) producing gellan-related polysaccharides are actually closely related members of genus Sphingomonas.
• Sphingan-producing bacteria share characteristic fatty acid profiles dominated by cis-vaccenic acid (18:1 cis-11) and distinctive methanol-soluble pigment absorption spectra different from other yellow-pigmented bacteria like Xanthomonas campestris.
• All sphingan producers exhibit consistent biochemical properties: aesculin hydrolysis positive, MacConkey agar growth negative, oxidase negative, and catalase positive, supporting their taxonomic reorganization.
• The capacity for sphingan polysaccharide production appears to be a common characteristic of Sphingomonas species, suggesting additional strains may produce commercially useful polysaccharides under appropriate culture conditions.