Biocellulose Production by Gluconacetobacter hansenii ATCC 23769: Application of Statistical Experimental Designs and Cellulose Membrane Characterization.

Abstract

In this study, an optimization of the culture parameters used for the production of bacterial cellulose (BC) by G.hansenii ATCC 23769 was carried out. This is the first study reported statistical optimization of the fermentation medium by Plackett–Burman Design (PBD) and Box–Behnken Designs (BBD) for BC production by type strain G.hansenii ATCC 23769. The effect of seven culture parameters on BC production was evaluated by implementing PBD, where the results revealed that, the most significant variables affecting BC production were yeast extract, temperature and incubation time. Response surface methodology (RSM) using BBD was applied to find out the optimum level of each significant variable. The optimal levels of the three significant components were found to be yeast extract 13 g/l, temperature 26.3°C and incubation time 12 days with a predicted yield 2.91 g/l. According to the results of the PBD and BBD the following medium composition is expected to be optimum (g/l): mannitol 25, yeast extract 13, ethanol 7 ml/l, pH 7, inoclume size 7%, temperature 26.3°C and incubation time 12 days. Characterization of dried BC membrane was carried out to determine the morphological structure and purity by Scanning Electron Microscopy (SEM), crystallinity by X-ray Diffraction (XRD), chemical structure and functional group by Fourier -Transform Infrared spectroscopy (FT-IR), and thermal stability by Thermogravimetric Analysis (TGA). In addition, mechanical properties such as: the Young’s modulus, tensile strength, elongation at beak % and thickness of BC membrane obtained from G.hansenii ATCC 23769 were determined.