Statistical optimization and characterization of a biocellulose produced by local Egyptian isolate Komagataeibacter hansenii AS.5

Abstract

Optimization of the culture parameters used for biocellulose (BC) production by a previously isolated bacterial strain (Komagataeibacter hansenii AS.5) was carried out. The effect of nine culture parameters on BC production was evaluated by implementing the Plackett-Burman design, and the results revealed that, the most significant variables affecting BC production were MgSO4, ethanol, pH and yeast extract. A three-level and four-factor Box–Behnken design was applied to determine the optimum level of each significant variable. According to the results of the Plackett–Burman (PBD) and Box–Behnken designs (BBD), the following medium composition and parameters were calculated to be optimum (g/l): glucose 25, yeast extract 13, MgSO4 0.15, KH2PO4 2, ethanol 7.18 ml/l, pH 5.5, inoclume size 7%, cultivation temperature 20 °C and incubation time 9 days. Characterization of purified BC was performed to determine the network morphology by scanning electron microscopy, crystallinity by X-ray diffraction, chemical structure and functional groups by Fourier-transform infrared spectroscopy, thermal stability by thermogravimetric analysis and mechanical properties such as Young's modulus, tensile strength and elongation at beak % of BC.