Abstract: Komagataeibacter nataicola Y19 was statically cultured at 30 ℃ for 7 days in media with either cell-free filtrate or cell residue of naturally fermented coconut water (FCW). As a result, the production of bacterial cellulose (BC) in the medium with the filtrate was 5.65 g/L, which was 10 times as high as that in natural coconut water (NCW) compared to 2.8 times for the medium with the cell residue, suggesting that the filtrate of FCW significantly promotes BC synthesis. Changes in organic acid contents in the filtrate during the fermentation of coconut water were analyzed by gas chromatography-mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC). The total amount of volatile compounds in the filtrate was about 5 times as high as that in NCW. Alcohols were the major volatile components in the filtrate, accounting for approximately 62% of the total amount, and the contents of ethanol and acetic acid were 4.5 and 48 times as high as those in NCW, respectively. The contents of acetic and lactic acid gradually increased during the fermentation process, while the contents of all other organic acids except gluconic acid, significantly decreasing from day 1 to 3, did not significantly change. Hence, it was deduced that microbial metabolites generated during the fermentation of coconut water make an important contribution to BC synthesis, and that the alcohols and acids greatly changing after the fermentation may affect BC synthesis by participating in regulating the metabolism of K. nataicola Y19.

Key words: membrane filtration, pre-fermented coconut water, bacterial cellulose, promoting effect