Bacterial cellulose (BC) is a natural exopolysaccharide characterized by high purity, mechanical strength and the ability to absorb various compounds [1]. These unique properties mean that BC can be successfully used in the food industry as, for example, food packaging and biomedicine as, for example, wound dressing material [2,3]. Obtaining BC on an industrial scale is expensive, mainly due to the high cost of culture media. Replacing classical media with waste from the agri-food industry may be a promising way to reduce the costs of obtaining BC [4]. The aim of this research was to evaluate the possibility of obtaining BC in waste media by Gluconacetobacter hansenii ATCC 23769 and to characterize its chemical and mechanical properties. YPM medium was used as a classical control medium. Hemp pomace (HP)-based medium in two concentrations of waste (15 and 20 g·dm-3) and acid whey (AW) were used as waste media. The obtained BC was analyzed chemically and structurally by Fourier transform infrared spectroscopy - FTIR, and mechanical properties: strain at break, stress at break and Young Modulus were evaluated. Based on the results obtained, no statistically significant differences were observed between the amount of BC produced by Ga. hansenii in YPM medium and waste media. The highest amount of BC was produced in YPM medium (1.06±0.028 g·dm-3), while among the waste media, the highest BC biosynthesis efficiency was provided by HP20 medium (0.95±0.197 g·dm-3). FTIR analysis showed that the spectra of BC obtained in HP media (regardless of concentration) differed slightly from that of BC produced in YPM media. Peaks at wavenumber 1734 cm-1 and 1738 cm-1 (HP15 and HP20, respectively) were observed, probably corresponding to C=O stretching vibrations in the O=C-OH group of the glucuronic acid unit in hemicellulose, which may have originated from hemp pomace [5]. BC obtained in AW medium had the highest Total Crystalline Index (TCI) among the waste media indicating higher degree of crystallinity and more ordered cellulose structure. BC from HP15 medium showed the highest strain at break (4.28±1.47%). Strain at break for BC from YPM medium was 1.84±0.78%. BC obtained in AW had the highest Young's Modulus (2122±1152 MPa) of all media and statistically not different from BC from YPM medium (1538± 885MPa). These studies have shown that it is possible to obtain BC from waste media with similar biosynthetic efficiency to classical media. In addition, BC obtained in waste media may have improved mechanical properties, which in the future may result in expanding the application possibilities of BC.
Characterization of BC was conducted during a Justyna Płoska scholarship at Slovak University of Technology funded by the Polish National Agency of Academic Exchange (NAWA) in Exchange Programme for Students and Scientists as Part of Bilateral Cooperation, No. BPN/BIL/2021/1/00171/U/00001.