1a shows the amounts of BC production from various car-bon sources. After 7 days incubation, the production of the BC wasconfirmed from three media. However, more BC cultured in mediaZhou (Z) and Hestrin-Schramm (H) was produced, respectively.Moreover, it was confirmed that G. xylinus could not produce BCin the medium consisting of Yamanaka (Y). The nitrogen sourcessuch as yeast extract and pepton were indispensable for the cellgrowth and BC production. It is therefore suggested that suchnitrogen sources should be included in the media. The dry BCweight produced from the medium that consisted of mannitol andsucrose was the maximum. Although the production of sucrosein all media is the same (Fig. 1), the BC was slightly produced inZhou medium (1.59 g L−1). Therefore, it is thought that the manni-tol and sucrose could consist of promoting substance for productionof the BC. From the above-mentioned observations, it is thoughtthat the mannitol and H was the most suitable condition for the BCproduction.