Nata-de Coco is one kind of popular foods that have been consumed world-wide and in Vietnam as well. It is fermented product from coconut juice by a role of Acetobacter xylinum, including cellulose as an essential component in the final product This research was carried out to investigate the cellulose producing Acetobacterstrains and the effect of fermentation conditions on their cellulose production. Total aerobic microorganisms in 3 samples of nata fermenting medium collected at local producers in Ben Tre was in the range of 8.92 - 9.14 log CFU/ml. Seven bacterial strains were isolated and identified as belonged to Acetobacter genus based on the morphology examinations and biochemical characteristics. The bacterial colony had round form with lightly yellow colour. These bacterial strains were gram negative, rod, catalase positive, giving bright halo zone in YPGD medium supplemented with 0.5 percent CaCO3 and 4 percent ethanol, converting medium colour from green to yellow when supplemented bromocresol green. Strain Acetobacter N was found to give the highest yield of cellulose production. By testing the fermentation conditions for cellulose production, the results showed that the highest cellulose level was achieved when produced with conditions as below: use of coconut liquid medium that was naturally fermented 60 hours before, level of inoculation at 6 log cells/ml, the initial adding sugar content at 50 brix and level of adding diamonium hydrogen phosphate (DAP) at 0.2 percent.
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