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Mirage NewsScience19 Aug 2026 12:40 pm AESTDate Time
Feeding bacteria a cheap agricultural by-product enables the production of high-value biomaterials with promising biomedical and industrial applications
Schematic illustration showing how carbon source selection influences the structure and biological properties of exopolysaccharides (EPS) produced by Bacillus velezensis AZU-A3. Sucrose-derived EPS (EPS-S) exhibited a mannose- and uronic acid-rich composition with a more ordered helical-like conformation, whereas sugarcane molasses-derived EPS (EPS-M) showed a glucose-rich composition with a more flexible molecular structure. These substrate-dependent structural differences were associated with enhanced antioxidant and antibacterial activities of EPS-M. (Mohamed I. A. Ibrahim / Hiroshima University)
Changing the carbona are fed-can significantly influence the properties of the sugar polymers they produce, known as bacterial exopolysaccharides (EPSs)
These EPSs are secreted by bacteria into their surroundings, where they form protective layers or biofilms and serve as valuable materials for a wide range of medical and industrial applications
“A simple change in the carboncal activity of the bacterial exopolysaccharides,” said Mohamed Ibrahim, a specially appointed associate professor at Hiroshima University’s Research Institute for Synchrotron Radiation Science (HiSOR) and lead author of the study
Researchers at Hiroshima University compared the effects of two distinct carbon substrates-refined sucrose and sugarcane molasses, an inexpensive agricultural by-product-on the EPSs produced by the bacterium Bacillus velezensis AZU-A3. Using vacuum-ultraviolet circular dichroism spectroscopy at Hiroshima University’s HiSOR, together with chromatographic tools, the team mapped the structural variations among the resulting polymers
The results, published in the Chemical Engineering Journal on June 23, 2026, showed that refined sucrose yielded a biopolymer (EPS-S) characterized by an ordered, helical-like molecular conformation. Conversely, sugarcane molasses produced a glucose-rich biopolymer (EPS-M) with a more flexible molecular conformation
This greater structural flexibility allowed the low-cost molasses derivative to outperform its refined counterpart in biological tests. The EPS-M demonstrated superior antioxidant capabilities, achieving 94.23% free-radical scavenging activity, compared with 76.43% for EPS-S. It also exhibited significantly stronger antibacterial activity against common pathogenic strains, including Escherichia coli, Salmonella enterica, and Staphylococcus aureus
Bacterial EPSs are widely used in pharmaceuticals, medical coatings, surgical sealants, and drug delivery systems because of their biocompatibility, biodegradability, and low toxicity. However, understanding the complex relationship between polysaccharide structure and biological function has remained a persistent challenge. “Understanding this relationship enables researchers to tailor EPS properties, improve their antioxidant and antibacterial activities, and develop cost-effective production methods using inexpensive substrates such as sugarcane molasses,” Ibrahim said.
These findings offer a sustainable and economically, pharmaceutical, and food industries
“Our next step is to investigate the molecular mechanisms by which different carbons and genes responsible for changes in monosaccharide composition, molecular conformation, and biological activity,” said Ibrahim
“We also plan to evaluate these EPSs in more advanced biological models and optimize production using sustainable substrates.”
The study was conducted by Abdelrahman M. Khattab, Mahmoud E. Esmael, Ryota Imaura, Amr A. Nassrallah, Hany A. El-Shemy, Koichi Matsuo, and Mohamed I.A. Ibrahim, researchers from Al-Azhar University, Cairo University, the Egypt-Japan University of Science and Technology, the National Institute of Oceanography and Fisheries, and Hiroshima University. Matsuo is a researcher at the International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM²), the Research Institute for Semiconductor Engineering, and the Research Institute for Synchrotron Radiation Science at Hiroshima University, where Ibrahim also serves as a specially appointed associate professor.
About the study
- Journal: Chemical Engineering Journal
- Title: Carbon source modulates composition, conformation, and activity of exopolysaccharides from Bacillus velezensis AZU-A3
- Authors: Abdelrahman M. Khattab, Mahmoud E. Esmael, Ryota Imaura, Amr A. Nassrallah, Hany A. El-Shemy, Koichi Matsuo & Mohamed I.A. Ibrahim
- DOI: 10.1016/j.cej.2026.178735
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