Selection of bacterial cellulose producing acetic acid bacteria from kombucha tea and evaluation of the influence of culture conditions on bacterial cellulose production.

Bacterial cellulose (BC) from Acetic Acid Bacteria is widely investigated as biopolymer for different applications. The interest in BC is due to its highwater holding capacity, good mechanical strength, elasticity and high crystallinity. Among Acetic Acid Bacteria, Komagataeibacter xylinus plays the most important role because it is considered the highest producer of BC. However, the BC production can be strongly affected by several variables. In this context, the aim of this work was to perform an initial screening among 10 strains belonging to Komagataeibacter sp. and Novacetimonas sp., previously isolated from kombucha samples in order to select the strain able to produce the highest amount of BC. Then, the effects of different culture parameters (pH, Temperature, sources of carbon and nitrogen) were evaluated on the selected strain and specifically, on their capacity to produce BC in static cultivation. Among the tested strains, Komagataeibacter sp. showed the highest yield of BC production during static fermentation in medium containing glucose or mannitol as carbon source. Regarding the effects of culture conditions, the results showed that all the parameters tested affected the yield of BC production. Among the carbon sources, mannitol, glucose and fructose allowed to obtain the highest yield of BC. Regarding nitrogen source, yeast extract gave the highest yield. The pH (4–6) resulted suitable for BC production. The temperature of 25-30 °C resulted optimal for BC production with the higher yield obtained at 30 °C. The results of this study provide further insight into the role of strain selection, medium composition and physico-chemical fermentation parameter control in the improvement of BC production by acetic acid bacteria during static fermentation.