Biotransformation of waste glycerol to bacterial cellulose

Lidia Stasiak-Różańska Lidia Stasiak-Różańska 1 Monika Garbowska 1 Justyna Płoska 1

1Warsaw University of Life Sciences, Institute of Food Sciences, Warsaw, POLAND

The production of biofuels in the EU countries, as well as around the world, is growing dynamically. The biodiesel production process involves transesterification and is always associated with the formation of a by-product - waste glycerol. The amount of glycerol waste is constantly increasing every year. It is worth looking for a new directions for the utilization of this waste, which are safe for the natural environment. Bacterial cellulose (BC) is a natural biopolymer, produced, inter alia, by some strains of acetic bacteria in a reaction catalyzed by a cellulose synthase complex. BC is made of nanofibers, forming a three-dimensional network of polysaccharide chains, connected by β-1,4-glycosidic bonds. Bacterial cellulose shows good mechanical properties and a high degree of crystallinity. It is also characterized by high water-holding capacity and biocompatibility with human skin. Depending on the temperature, pH or ionic strength, BC shows the ability to swell. Bacterial cellulose was recognized by the Food and Drug Administration in 1992 as a polymer safe for human health and life, which allows its use also in food technology. The main aim of the undertaken research was to determine the possibility of waste glycerol utilization do bacterial cellulose with the use of acetic bacteria. It was assumed that the results of the conducted research will provide the basis for the development of an effective method of biotransformation of waste glycerol fraction from biodiesel production  into  bacterial cellulose - a natural biopolymer with high industrial application potential. Materials and methods: Gluconobacter oxydans ATCC 621, Gluconacetobacter hansenii ATCC 23 769. Waste glycerol fraction from biodiesel production (BIOAGRA-OIL S.A., Tychy, Poland). Growth media for BC production [gL-1]: yeast extract 20, glucose 20, waste glycerol (30, 50 or 100), pH 5.5. After washing and drying, the bacterial cellulose was weight and the texture profile analysis was made. The results showed that bacterial cellulose obtained in the medium with 30 gL-1 waste glycerol was characterized by the highest hardness and adhesiveness, and its elasticity and gumminess were similar to the bacterial cellulose obtained in the control medium. Moreover it was assumed that the higher the initial concentration of waste glycerol in medium, the longer time needed to obtain bacterial cellulose. The most important conclusion is that there is a possibility to utilize the waste glycerol after biodiesel production to bacterial cellulose with using the strain Gluconacetobacter hansenii ATCC 23 769.