Identification a Novel Raw-Starch-Degrading-α-Amylase from a Tropical Marine Bacterium

• Main Authors: Zeily Nurachman, Alfredo Kono, Ocky K. Radjasa, Dessy Natalia
• Format: Publication
• Language: English
• Published: Science Publications 2010
• Subjects: Acropora< alpha; amylase; amylolytic enzymes; Bacillus amyloliquifaciens< C-terminal domain; Glycosyl Hydrolase (GH); hard coral < i> lt; marine bacterium; Marine Broth (MB); Thin Layer Chromatography (TLC); yielded oligosaccharides

Problem statement: Bacteria from the surface of the tropical marine hard coral Acropora sp. were screened for producing raw-starch-degrading-᭡mylase. Approach: Based on its 16s rDNA sequence, a bacterium that produced the highest amylolitic activity was identified as Bacillus amyloliquifaciens ABBD. The bacterial isolate secreted a ᭡mylase extracellularly and then the enzyme was partially purified by ammonium sulfate precipitation followed by anion exchange chromatography. Results: Electrophoresis results both SDS-PAGE and native PAGE suggested that the enzyme was a heterodimeric protein (97 kDa) consisting of 45 and 55 kDa subunits. The ᭡mylase had an optimum pH of 7.0 and temperature of 60C. More than 80% activity of the enzyme was retained under high salt conditions (up to 20% NaCl). The enzyme remained stable at 50C for 1 h. Starch hydrolysis by the enzyme at 70C yielded oligosaccharides (G2-G4) and at room temperature yielded glucose/maltose (G1 and G2). Conclusion: The B. amyloliquifaciens ABBD ᭡mylase was capable of degrading various raw starch granules from corn, rice, cassava and sago at room temperature.