Optimal system of bacterial cellulose production as an alternative of plant cellulose

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Bacterial cellulose (BC) was produced by a bacterium, Acetobacter xylinum BPR2001 and the following results were obtained.(A) Cultivation by an airlift reactor(1)BC productivity by the A.xylinum was enhanced when the oxygen-rich air was supplied into the airlift reactor and the productivity was comparable to that in a jar fermentor.When fructose as a carbon source was increased to 60-70g/l, the highest production rate of 0.22 g/l/h which was two-fold of the previous data and the yield of BC to sucrose of 35% were assessed. The BC obtained in an airlift reactor was formed to be unique pellets and the diameter of the pellets was smaller when the productivity of BC was higher. The carbon balance of the cultivation revealed that the production of carbon dioxide and other carbon containing byproducts was reduced when the productivity was higher, indicating that the energy efficiency was increased.(2) addition of water-soluble polysaccharides like agar or xanthan into the medium increased the productivity of BC, presumably due to increase in viscosity and this caused the clump formation of cells and BC.(B) Cultivation in a jar fermentorThe 10 liter jar fermentor was used to compare the production of BC with that in airlift reactor. The production of BC was reduced about 10% in a jar fermentor when 70g/l of fructose was used. The enhanced effect of BC production was not observed when water-soluble polysaccharides were added.(C) Comparison of airlift reactor and jar fermentorWhen fructose concentration was moderate, the productivity of BC between the two reactors was not different. However, when the fructose concentration was increased, the production of BC in an airlift reactor was significantly higher than that in a jar fermentor. The consumed energy in the airlift reactor was one-fifth to one-sixth of the jar fermentor.