2. An industrially interesting source of EPS: the rhizosphere

In "bare" soil (without plant cover), in the absence of readily available sources of carbon and energy, microbial activity slows down. During the plant's active growth phase, a significant fraction of its photosynthate (8-12%) is released into the soil, mainly in the form of carbohydrates (glucose, fructose, etc.). . The rhizosphere, the part of the soil surrounding living roots, is the site of this root exudation. The molecules released at the root surface are available to bacteria, particularly those that are heterotrophic for carbon. Among these bacteria, known as "rhizobacteria", a fraction are capable of transforming these carbohydrates into polymers (EPS).

The presence of high carbohydrate concentrations on the root surface is probably necessary to induce...