2. Biosynthesis

Xanthan gum is synthesized and excreted by the bacterium Xanthomonas campestris. This micro-organism is strictly aerobic (it develops only in the presence of oxygen) and takes the form of medium-sized shells or small rods (0.5 x 1.3 µm). The classification of Xanthomonas species is based on their phytopathogenicity. More than 140 X. campestris pathovars are listed. Xanthomonas campestris, a member of the Pseudomonades group, belongs to the gram 2 category (membrane staining technique developed by Christian Gram in 1884). The gram-2 wall has a complex structure consisting of a plasma membrane containing proteins and phospholipids, a periplasmic space containing peptidoglycan (a heteropolymer of N-acetyl-glucosamine and N-acetylmuramic acid linked by peptides) and an outer membrane rich in functional proteins, lipopolysaccharides and lipoproteins. Industrialists have progressively improved...