Utilization of acetate buffer to improve bacterial cellulose production by Gluconacetobacter xylinus

Abstract

The bacterial cellulose (BC) pellicle produced from Gluconacetobacter xylinus has many attractive properties to be used in food and biomedical applications. However, the by-product, gluconic acid produced during BC production will decrease the pH of culture that usually leads to a significant decrease of BC production by G. xylinus. To well control the pH of a static cultivation for BC pellicle production is not an easy task. In this study, acetate buffer was employed to maintain a pH suitable for BC production during static cultivation. The effect of buffer pH, ionic strength and surface area/volume (S/V) ratio of cultured medium on BC production was investigated. BC produced from 200 mM, pH 4.75 acetate buffered medium was 3.56 g/L, much higher than that obtained from YPD medium (0.66 g/L) and HS medium (1.23 g/L), respectively. When G. xylinus was cultivated at high glucose concentration (60 g/L) at S/V ratio of 0.55 cm−1, the BC produced and conversion were improved to 7.23 g/L and 0.2, respectively. As S/V ratio increased to 1.31 cm−1, a larger amount of gluconic acid (41.55 g/L) was obtained but with a slightly decreased BC production to 5.24 g/L. The results demonstrated that acetate buffered medium can effectively improve BC pellicle production in a static cultivation.