Characterization of thermo/halo stable cellulase produced from halophilic Virgibacillus salarius BM-02 using non-pretreated biomass

Abstract

The production of extremozymes from halophilic bacteria has increased significantly due to their stability and efficiency in catalyzing a reaction, as well as their capacity to display optimum activity at various salt concentrations. In the current study, the halophilic bacterium Virgibacillus salarius strain BM-02 could utilize many non-pretreated substrates including cellulose, corn stover, sugarcane bagasse and wheat bran as a sole carbon source. However, wheat bran was the best substrate for achieving optimum saccharification yield (90.1%). The partially purified cellulase was active and stable at a wide range of pH (5–8) with residual activities > 58%. Moreover, it was stable at 5–12% of NaCl. Metal ions have a variable impact on the activity of partially purified cellulase however, Fe+3 exhibited the highest increase in the cellulase activity. The enzyme exhibited a thermal stability at 40, 50 and 60 °C with half-lives of 1049.50, 168.14 and 163.5 min, respectively. The value of Vmax was 22.27 U/mL while Km was 2.1 mM. The activation energy of denaturation Ed 69.81 kJ/mol, the enthalpy values (ΔHd) were positive, and the entropy values (ΔS) were negative. Therefore, V. Salarius is recommended as a novel promising halophilic extremozyme producer and agricultural waste remover in the bio-industrial applications. Graphical abstract: [Figure not available: see fulltext.].