Production of extracellular agarase from Priestia megaterium AT7 and evaluation on marine algae hydrolysis

Abstract

Agar is a common component biosynthesized from various marine algae species that is widely applied in various fields including food and pharmaceutical industries. However, the structural composition of agar is highly resisted against chemical and biological hydrolysis. Therefore, tremendous research is exploring various pretreatment strategies to break down the intrinsic chemical structural of agar linkage (i.e. neutral agarose and highly sulfated agaropectin) prior for its industrial potential usage. In this research work, a novel agar degrading bacterium was screened and isolated from agriculture soils. Molecular identification using nucleotide sequence of 16 s rRNA region comparison has indicated that the isolate belonged to Priestia genus, and was identified as Priestia megaterium AT7. The maximum enzyme activity was 52.85 ± 1.76 U/mL after 96 h of culture with 5% inoculum size and agitation speed of 180 rpm. Results indicated that the optimal condition for the production of agarose was achieved at pH 7 at 50 °C. The effects of metal ions (e.g. Ca²⁺, Co²⁺, Cu²⁺, Mn²⁺, Mg²⁺, Zn²⁺ and Fe²⁺) and organic solvents (e.g. acetone, ethanol, methanol, hexane and isopropanol) on enzyme activity were also evaluated. Marine algae hydrolysis evaluation at concentration of 0.1% indicated the enzyme produced reducing sugar of 683.94 ± 26.93 µg/g after 24 h of treatment. It was also found that the highest antioxidant activities obtained after 20 h of treatment was able to achieve 81.76 ± 3.90% at marine algae concentration of 0.1%. The findings obtained from this research work shows the promising application of extracellular agarase to saccharify marine algae for the recovery of value-added bioproducts.

Keywords: Agar; Algae hydrolysis; Extracellular agarase; Molecular identification; Priestia megaterium.