Antimicrobial Activity of Bacterial Cellulose from Komagataeibacter xylinus using Expired Commercial Sweet Drinks as a Source of Carbon

Abstract

Bacterial cellulose (BC) is an important biopolymer to the food industry because of its unique properties such as high in water holding capacity (WHC) and mechanical strength. BC has the potential to be innovated with the addition of preservatives to solve the problem of food contamination by pathogenic bacteria. Komagataeibacter xylinus is able to produce high amount of BC through fermentation process. However, the process involves the use of high cost substrates. Therefore, this study was conducted to produce BC from low value sources such as expired sugary drinks, and to evaluate the antimicrobial properties of BC against Salmonella Typhi. During the first phase of the study, the factors influencing the production of BC were studied. Results showed that the optimal period for BC production was on the 10th day of fermentation with 122.06 g/l BC produced. The pH value decreased from 5.82 on day 0 to 3.95 after 12 days of fermentation. Sucrose and protein concentrations decreased significantly (p <0.05) during the fermentation period. The WHC for BC was 22.53 g water/g cellulose and the water absorption rate increased as the immersion time increased. Biodegradation tests showed that wet BC decomposed faster (95.85%) compared to dry BC (68.1%) after 8 days of analysis. In the second phase of the study, dry and wet BC were supplemented with sodium benzoate and potassium sorbate at different immersion times (0.5, 3, 6, and 24 h) and different concentrations (25, 50, 100, 250, 500, and 1000 mg/mL). Results showed that BC was able to absorb antimicrobial agents and successfully inhibited the growth of S. Typhi. Wet BC showed the largest inhibition zone (29 and 17.5 mm) compared with dry BC (12 and 14 mm) at 24 h of immersion in a concentration of 1000 mg/mL of sodium benzoate and potassium sorbate solution, respectively. This study shows the potential of bacterial cellulose to be used as an active packaging to extend the shelf life of food.