Xanthan and gellan degradation by bacteria of activated sludge

Owing to increasing amounts of xanthan and gellan in food, cosmetics and pharmaceuticals, as well as in some technical spheres, studies were carried out on the xanthan and gellan degrading bacteria present in activated sludge. The activated sludge used in the study was able to degrade both carbohydrates over 7 days, with levels of xanthan and gellan utilizing microbes estimated at 10⁵ cells/g of dry sludge weight. Isolating key degrading bacteria revealed the important role of genus Paenibacillus in xanthan degradation and prosthecate bacterium Verrucomicrobium sp. GD, which was capable of gellan utilization. Further tests performed with both strains showed they were able to degrade other types of carbohydrate polymers, and that Verrucomicrobium sp. GD did not possess extracellular free gellan depolymerase.