Bacterial cellulose (BC, biocellulose) is a natural and environmentally friendly exopolysaccharide produced by acetic bacteria, including the genera Gluconacetobacter and Komagataeibacter. BC is composed of linear ß-1,4-glucan chains linked by hydrogen bonds, van der Waals forces, and hydrophobic interactions. Bacterial cellulose is characterized by biodegradability, mechanical strength, permeability to liquids and gases, ability to adsorb various compounds, and biocompatibility with living tissues. However, despite its many advantages, biocellulose is still not widely used. One of the limitations associated with its production are the high cost of culture media and low process efficiency. One of the proposed approach to exclude this problem is the use of industrial wastes (such as acid whey) as substrates to provide high efficiency of BC obtaining.
The aim of this study was to evaluate the effect of lactic acid addition on the yield of bacterial cellulose in acid whey medium. In this study, a culture of Komagataeibacter xylinus K2G30 was carried out in acid whey medium (70 gL-1), where the pH was adjusted to 3.0, 3.5, 4.0, 4.5 and 5.0 with lactic acid. The addition of lactic acid was: 1.3%, 0.5%, 0.2%, 0.05% and 0% v/v respectively. A control experiment was conducted in the same medium but where the pH was adjusted with HCl. To better understand the process of BC biosynthesis in lactic acid-enriched whey, pH and total sugars were analyzed before and after culture in both experiments. The results show that the lactic acid content of the acid whey medium significantly affected the amount of bacterial cellulose obtained. The weight of BC increased in direct proportion to the amount of lactic acid addition. The highest yield of BC 7.22 g·L-1 was obtained in the medium where the acid addition was 1.3% which corresponded to pH 3.0. The lowest BC of 1.16 g·L-1 was obtained in the medium at pH 5.0 which was not supplemented with lactic acid. In a parallel control culture no statistically significant differences in BC yield depending on pH were observed. The mass of cellulose obtained ranged from 1.23 g·L-1 to 2.85 g·L-1 for pH 5.0 and 3.0, respectively. This indicates that BC production was determined by lactic acid content rather than low pH environmental conditions. Addition of lactic acid to the medium positively influenced the efficiency of BC production by Komagataeibacter xylinus, therefore it is reasonable to continue the study on whey with lactic acid in the future.