Molasses as fermentation substrate for levan production by Halomonas sp.

Area of Science:

• Biotechnology
• Microbial Production
• Biopolymer Science

Background:

• Levan, a fructose homopolymer, possesses valuable properties but faces production cost challenges.
• Current levan production relies on costly methods using mesophilic bacteria or plants.
• Halomonas sp. AAD6, an extremophilic bacterium, shows potential for high-titer levan production from sucrose.

Purpose of the Study:

• To investigate the feasibility of using pretreated molasses as a cost-effective substrate for levan production by Halomonas sp. AAD6.
• To optimize levan yield and characterize the produced biopolymer.
• To assess the biocompatibility of levan derived from molasses.

Main Methods:

• Five different pretreatment methods were applied to sugar beet and starch molasses.
• Halomonas sp. AAD6 was cultivated on pretreated molasses.
• Biomass and levan concentrations were measured.
• Molecular characterization, monosaccharide composition, and rheological properties were analyzed.
• Biocompatibility assays were performed on cancerous and non-cancerous cell lines.

Main Results:

• Pretreated sugar beet molasses and starch molasses proved to be effective substitutes for sucrose.
• Halomonas sp. AAD6 achieved high levan production (12.4 g/L) using pretreated beet molasses.
• The produced biopolymer was confirmed as levan-type fructan with typical low viscosity and pseudoplastic behavior.
• Levan from molasses exhibited excellent biocompatibility and cell line affinity.

Conclusions:

• Pretreated molasses offers a sustainable and economical alternative substrate for levan production.
• Halomonas sp. AAD6 demonstrates superior levan yield, particularly from fructose-rich substrates like molasses.
• Molasses-derived levan holds promise for various applications due to its favorable properties and biocompatibility.