A Novel EPS-Producing Strain of Bacillus licheniformis Isolated from a Shallow Vent Off Panarea Island (Italy)

A haloalkaliphilic, thermophilic Bacillus strain (T14), isolated from a shallow hydrothermal vent of Panarea Island (Italy), produced a new exopolysaccharide (EPS). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain T14 was highly related (99 % similarity) to Bacillus licheniformis DSM 13^T and Bacillus sonorensis DSM 13779^T. Further DNA–DNA hybridization analysis revealed 79.40 % similarity with B. licheniformis DSM 13^T and 39.12 % with B. sonorensis DSM 13779^T. Sucrose (5 %) was the most efficient carbon source for growth and EPS production. The highest EPS production (366 mg l^?1) was yielded in fermenter culture at 300 rpm after 48 h of incubation. The purified fraction EPS1 contained fructose/fucose/glucose/galactosamine/mannose in a relative proportion of 1.0:0.75:0.28:tr:tr and possessed a molecular weight of 1,000 kDa displaying a trisaccharide unit constituted by sugars with a β-manno-pyranosidic configuration. Screening for biological activity showed anti-cytotoxic effect of EPS1 against Avarol in brine shrimp test, indicating a potential use in the development of novel drugs.