Bacterial cellulose production by selected acetic acid bacteria on different Agrifood by-products.

Bacterial cellulose (BC) is produced by certain acetic acid bacteria (AAB) and represents a valuable biopolymer due to its interesting mechanical and technological properties. However, the production cost represents the main limitation to the industrial production of this biomaterial. In this scenario, Agrifood by-products represent a cheaper and naturally rich sources of nutrients which are suitable for microbial fermentation and thus, for BC production. In this study, the growth kinetics and BC production of Novacetimonas hansenii 6DB, Komagataeibacter rhaeticus LM2, LM4 and SM1 and Komagataeibacter xylinus DSM 2004 were investigated using beet molasses, brewer’s spent grains and yeast and cheese whey as growth media. The results revealed that BC productivity was affected by the AAB strain and agrifood by-product considered. Under optimized conditions, the highest BC yields, after 10 days of incubation at 28°C, were achieved by the strains DSM 2004 (2.878 g/L) and LM4 (1.698 g/L) using beet molasse as growth medium. Lower levels of BC were produced in brewer’s spent grains alone whereas when combining it with brewer’s spent yeast and phosphate buffer all the AAB showed a BC dry weight higher than 1.1 g/L. The pH value of beet molasses and cheese whey media slightly decreased whereas that of the brewer’s spent grains medium was found to significantly decreased during the incubation at 28°C when the buffer was not added to the medium. It was also observed that cellulose production gradually increased with the increase of incubation time, but the rate of BC formation remained almost constant after 7 days. Beet molasse medium proved to be a more suitable substrate for BC production in comparison with brewer’s spent grains and cheese whey. Overall, this study demonstrated the potential of producing BC from wastes. However, a good understanding of the factors affecting BC production and the identification of the optimum conditions for a low-cost-effective BC production could significantly incentivize the expansion and the potential applications of this biomaterial in various industries and especially in the food industry.