Purification and Preliminary Characterization of an Agarase Enzyme by Marine Bacterium Aquabacterium citratiphilum...

The current study aims to isolate Aquabacterium citratiphilum EGDA30 from a marine environment for the first time and to demonstrate its ability to produce the agarase enzyme, which has not been reported previously. Additionally, the study aims to purify and characterize the produced agarase. This may help to identify a unique and efficient microbial source of the agarase enzyme. A GenBank accession number (PQ203724) was provided to the 16 S rDNA sequence. The purification process registered a 49.4-fold. Agarase was optimum between 30 and 50 °C, peaking at 40 °C. The agarase stability was obtained at 40 ℃ for 6 h and at 50 ℃ for 3 h, with remaining activities of 92.92% and 82.41%, respectively. Agarase worked optimally at a pH range of 7-10, peaking at pH 8. Agarase was stable at pH 8 for 6 h, with remaining activity of 92.22%. Ca²⁺ and Mn²⁺ ions increased agarase activity. 5 mM of Na⁺ ions increased activity slightly. Zn²⁺ and Fe²⁺ ions reduced the activity. Cu²⁺, Al³⁺, Hg²⁺, EDTA, and SDS inhibited agarase activity. The agarase activity was increased by β-mercaptoethanol, indicating that thiol groups may be found at the catalysis region. The findings indicated that the agarase was a non-metal ion-dependent enzyme. The values of Km and Vmax were 0.62 mg/mL and 11.37 U/mg, respectively. On SDS-PAGE, the molecular mass of agarase was 124 kDa. The present study reports a highly active and high-molecular-weight agarase from the marine bacterium A. citratiphilum EGDA30, which exhibits higher activity at moderate temperatures (30-50 ℃) as well as under neutral and alkaline conditions, making it promising for different uses in the future.