#TITLE_ALTERNATIVE#

• Main Author: MAHATMANTO (NIM 20506004), TUNJUNG
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/9529
• Institution: Institut Teknologi Bandung

&#945;-Amylases (EC3.2.1.1) randomly hydrolyze &#945;-1,4-glucosidic bonds in starch, glycogen, and related polysaccharides to produce dextrins, oligosaccharides, maltose and glucose. These enzymes account for about 30% of the world's enzyme production and have a wide variety of industrial applications. Some of the industries that employ &#945;-amylases are starch converting, food, brewing, detergent, textile, and paper industry. Each application requires unique properties with respect to specificity, stability, and temperature and pH dependence. In recent years, direct enzymatic hydrolysis of raw starch has become a vital necessity for reducing the energy consumption in starch based industries. Exploration of new sources of &#945;-amylases and the characterization of the enzymes are essential in facilitating the discovery of novel &#945;-amylases that meet the industrial requirements with better properties, especially in raw starch degradation. One of the potential sources of &#945;-amylase yet to be further explored are the marine bacteria. The purpose of this research is to isolate and study the biochemical characteristics of a marine Vibrio sp. SFNB 3 &#945;-amylase.<p> <br /> <br /> <br /> <br /> <br /> At the temperature of 30oC and shaking of 150 rpm, Vibrio sp. SFNB 3 has a short growth phase in which the stationary phase was reached on the 6th hour of incubation. The extracellular &#945;-amylase synthesis by Vibrio sp. SFNB 3 followed the bacterial cell growth and thus is a growth associated type of synthesis. Vibrio sp. SFNB 3 produced more than one kind of &#945;-amylase with a specific activity of 11 U/&#956;g towards soluble starch under the assay condition. One of the &#945;-amylases has a raw maize starch binding ability. Isolation of the &#945;-amylase from Vibrio sp. SFNB 3 using raw maize starch gave a 30% yield with a 2 fold purification degree. The specific activity of the isolated &#945;-amylase is 21 U/&#956;g towards soluble starch under the assay condition.<p> <br /> <br /> <br /> <br /> <br /> Molecular weight determination by SDS PAGE showed that the isolated &#945;-amylase has a molecular weight of approximately 51 kDa. The temperature-activity profile showed that the isolated &#945;-amylase has a wide range of temperature for its activity. At the temperature range of 30-60 degrees C, the isolated &#945;-amylase has a relative activity above 88%. The optimum temperature for activity of the isolated &#945;-amylase is 50 degrees C. The T1/2 value of the isolated &#945;-amylase at this temperature is 194 minutes. The isolated &#945;-amylase worked at a wide range of pH. At the pH range of 5 to 8, the isolated &#945;-amylase has a relative activity above 85%. The pH-activity profile of the isolated &#945;-amylase exhibited an optimum activity at pH 8. The isolated &#945;-amylase is an endo amylase and degrades soluble starch giving a wide range of products, from glucose to maltoheptaose (G1-G7), after 48 hours of incubation at the temperature of 50oC. The isolated &#945;-amylase has a raw maize starch degrading ability, giving maltose to maltoheptaose (G2-G7) after 48 hours of incubation at the temperature of 37oC and shaking of 150 rpm. Scanning electron microscopy (SEM) displayed the presence of pores and large cavities on the surface of raw maize starch granules as a result of enzymatic hydrolysis by the isolated &#945;-amylase. The Km, Vmax and kcat value of the isolated &#945;-amylase is 10,7 mg/mL, 303 U/mL and 5 x 104 s-1, respectively. Based on these characteristics, the isolated &#945;-amylase from the marine Vibrio sp. SFNB 3 is a potential candidate for industrial application, especially in starch based industries.