Bioproduction
of exopolysaccharide by Agrobacterium tumefaciens using date molasses and their
potential applications
Halawani Eman Mohammed
Res. J. Biotech.; Vol. 21(1); 276-287;
doi: https://doi.org/10.25303/211rjbt2760287; (2026)
Abstract
The present study aimed to optimize the production of exopolysaccharides (EPS) by
Agrobacterium tumefaciens using dates molasses (DM) as a carbon source. Various
culture conditions, seed culture, inoculum size and nitrogen supplements were tested
to achieve maximum bacterial growth and EPS yield. After optimizing the media and
cultural conditions, the EPS was purified by gas-liquid chromatography. The purified
EPS was characterized for its functional properties including sugar composition,
viscosity, emulsification and serological properties. The results indicated that
DM has a high percentage of sugars (55.77%), with potassium as the main element
(60.40%). A. tumefaciens produced a single EPS at 96 hours of fermentation under
static conditions at 30 °C, 3 to 10% DM, 7 g/L KNO3 and 36 h of seed culture.
The succinic acid in the basal medium and inducing agents such as ribose, glucose
and sucrose stimulated the growth and EPS yield of the bacterium. D- glucose was
observed to be the main component in the purified EPS 100% glucose. The viscosity
property increased with EPS concentration and showed a reversible behavior as the
temperature rose from 10 to 100 oC. An emulsification of 45% was obtained in the
filtrate containing the EPS. The antisera against crude EPS showed activity in the
double immunodiffusion test, indicating that the crude acetone-precipitated polymer
was immunogenic. However, the pure polymer did not show any precipitation. Pure
EPS is non-toxic, emulsifying and non-immunogenic, making it suitable for blood
plasma expander or food additive.
