Eight isolates previously isolated from rhizoplane of sugarcane roots grown in Aswan Governorate, Egypt
and biochemically identified as Gluconacetobacter spp. were used to evaluate their cellulose production ability.
All isolates were subjected to a set of tests that proved their efficiency in producing cellulose i.e. formation of
white gelatinous pellicle, absence of precipitate, clear zone formation and yield of bacterial cellulose (BC).The
results cleared that the isolate SuGu9 was the potent one that produced 2.7 g/L BC. The isolate was identified
using 16S rRNA technique and found to be Komagataeibacter xylinus PP431972. This bacterium was known as
a modeling microorganism for cellulose production. The morphological, physiochemical and thermal properties
of BC produced were also estimated. The BC appeared as a rough surface related to fibrous structure of
cellulose by scanning electron microscopy (SEM) as well as SEM pattern appeared as longitudinal fibers. The
Fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD) graphs for the BC were typical
for BC of K. xylinus with 23% crystallinity. For the thermal stability, thermogravimetric analysis (TGA) curves
showed the percentage of weight loss for BC which gradually increased with the increasing of temperature and
maximum loss of weight (65.35%) was recorded at 577.7°C. Moreover, derivative thermogravimetry (DTG)
curve shows that the maximum rate of this transformation (641.0 μg/min.) occurs at temperature of
approximately 297.6°C. While differential scanning colorimetry (DSC) curves indicated that glass transition
temperature (Tg) of the BC films was found to be 174.9°C. |
