Levan is endowed with several characteristics that favor its use for biomedical and nutitional purposes, notably biodegradability, sustainability, flexibility, biocompatibility, and eco-friendliness. Its composition was shown to includeD-fructofuranosyl residues bound by β-(2,6) in the main chains and β-(2,1) linkages in side chains, with D-glucosyl as a terminal residue [1]. It is derived from a wide range of bacterial genera such as Acetobacter, Bacillus, Erwinia, Gluconobacter, Halomonas, Microbacterium, Pseudomonas, Streptococcus and Zymomonas are [2]. The microbial biosynthesis catalysis occurs due to the enzyme levansucrase that allows sucrose hydrolysis and transfructosylation with sucrose molecules or fructooligosaccharide chains as acceptors [3, 4]. Levansucrases synthetize low and high molecular mass levan from sucrose [5, 6]. Potential uses of levan have been reported in medicinal, cosmetic and food industries. It serves as an anti-tumor agent [7, 8] and a hypo-cholesterolemic agent [9]. It is also helps stimulate the immune system [10, 11], the probiotic bacterial growth [12, 13, 14], the antioxidant activity [15, 16, 17] and the antibacterial activity [18] (Byun, Lee, & Mah, 2014). In the food processing, levan is highly recommended as a thickener, stabilizer, viscosifier, emulsifier and flavour enhancer [19].
According to Tabilo-Munizaga and Barbosa-Cánovas [20], rheological assays are quite common for the physical characterization of raw material prior to processing, intermediate products during manufacturing, and end products. In recent years, the rheological properties of levans have been widely investgated [21, 22, 23]. They are subject to several factors including sugar composition, linkage type, branching degree, molecular weight and viscosity. These parameters depend on microorganisms, media, and culture conditions [24]. The optimization of microbial exopolysaccharide yield has been evaluated through a statistical approach [25, 19, 26].
Bacterial biofilms are clusters of bacteria that are fixed to a surface and/or to each other and attached in a self-produced matrix. Biofilms are of critical importance because they are implicated in all clinical infections [27]. Recently, levan received more and more attention due to their wide biological activities, including immunomodulatory [28] antibacterial [29, 30] antibiofilm [30] and anticancer [30] activities.
In the present study, Bacillus mojavensis levan yield was optimized by manipulation the medium composition according to the Response Surface Methodology (RSM). The production dynamics were depicted using mathematical models for the process variables. In addition, the FTIR, thermal behaviour, and solution rheology properties of this polymer were also carried out.