Fermentative production of Nata-de-cashew from calcium alginate incorporated cashew apple juice medium

Nata produced by Gluconacetobacter xylinum is a pure form of cellulose without lignin and hemicelluloses unlike plant cellulose. The production of bacterial cellulose or nata is receiving great attention due to its wide range of application both in food and pharmaceutical industries. However, the yield is comparatively very low and the commercially used carbon sources such as glucose are relatively expensive. In this study, a pilot scale bacterial cellulose production was carried out in a 5 L capacity model jar fermentor using G. oboediens (sju-1) Acc. No. KF164613 in calcium alginate incorporated cashew apple juice (CAJ) medium. Fermentation kinetics of bacterial cellulose production was evaluated during the course of reaction. The population increase with a gradual decrease in pH was noticed up to 16^th day of inoculation. Initially the population was 0.002 × 10¹¹cfu mL⁻¹, which increased to 13.24 and 25.21 × 10¹¹ cfu mL⁻¹ on 8^th and 10^th day, respectively. By 16^th day of incubation, the population reached the maximum of 34.12 × 10¹¹ cfu ml⁻¹ and the pH of the medium dropped to 4.5. Bacterial cellulose produced per 100 g of the substrate (Yp/s) was 1.62 ± 0.01g, while it was found to be 1.30 ± 1.11g. 100g⁻¹ of cells (Yp/x). With respect to total sugars, the initial concentration of 18.00 g.L⁻¹ dropped to 16.14, 10.88 and 9.14 g.L⁻¹ on 2^nd, 6^th and 8^th day, respectively. On the 16^th day when the population of bacterial cells was at the maximum, the total sugar content dropped drastically to 2.18 g L⁻¹. Due to the incorporation of calcium alginate in medium, the yield of nata-de-cashew increased and the mass production was found to be easier compared to the flask culture. Hence, it is concluded that, addition of calcium alginate to CAJ medium under static condition, inoculated with G. oboediens (sju-1) NCBI GenBank Acc. No. KF164613 in a modified jar fermentor could increase the production of nata.