Production of bacterial exopolysaccharides by solid substrate fermentation

In a comparison of submerged cultivation (SC) with solid substrate fermenta tion (SSF) for the production of bacterial exopolysaccharides (EPS), the la tter technique yielded 2 to 4.7 times more polymer than the former, on the laboratory scale. SSF was performed using inert solid particles (spent malt grains) impregnated with a liquid medium. The polymer yields obtained from SSFs, as referred to the impregnating liquid volumes, were as follows: 38. 8 g/litre xanthan from Xanthomonas campestris, 21.8 g/litre succinoglycan f rom Rhizobium hedysari and 20.3 g/litre succinoglycan from Agrobacterium tu mefaciens PT45. These results make this technique promising for a potential application on the industrial scale. A further advantage with this ferment ation process is found in the availability and low cost of substrates, whic h are obtained as by-products or wastes from the agriculture or food indust ry. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.