PRODUCTION AND BIOCHEMICAL CHARACTERIZATION OF SCLEROTINIA SCLEROTIORUM α-AMYLASE ScAmy₁: ASSAY IN STARCH LIQUEFACTION TREATMENTS

• Published in: Journal of food biochemistry 2008-10, Vol.32 (5), p.597-614
• Main Authors: KHEDHER, IMEN BEN ABDELMALEK, BRESSOLLIER, PHILIPPE, URDACI, MARIA-CAMINO, LIMAM, FERID, MARZOUKI, M. NEJIB
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Food industries; Fundamental and applied biological sciences. Psychology; Starch and starchy product industries
• ISSN: 0145-8884; 1745-4514
• DOI: 10.1111/j.1745-4514.2008.00193.x

Among the lytic enzymes secreted by the phytopathogen fungus Sclerotinia sclerotiorum, a starch-degrading activity has been isolated and characterized. Two extracellular α-amylases were produced in culture medium in presence of oats flour as carbons sources. An endoamylase named ScAmy1 was purified to homogeneity by ammonium sulfate precipitation, phosphocellulose and cation exchange high performance liquid chromatographies. Molecular mass of purified ScAmy1 was estimated as 54 kDa. Amylase exhibits maximal activity at pH 5 to 6 and at temperature 60C. ScAmy1 was stable in a pH range of (5-11) and at 50C. Initial activity was still conserved 40%, after heating at 60C during 30 min. In addition, Ca²⁺activate and stabilize the enzyme. Starch end products were determined as low molecular oligoglucanes, the liquefying power of ScAmy1 was also tested with the Amylograph Brabender, results suggest a suitable application of ScAmy1 in several industrial process. α-Amylase ScAmy₁ was highly produced from Sclerotinia sclerotiorum on oats flour - a cheaper by-agro-substrate product. The enzyme was purified and biochemical characterized. ScAmy₁ was applied in starch liquefaction treatments assay. The enzyme allows a decrease in peak viscosity after gelatinization and therefore has an important liquefying power. ScAmy₁ has a nearly liquefaction effect on flour compared to the commercial enzyme Novamyl, from Novozymes, donated by Novo Nordisk Co. (Denmark). Enzyme end products were analyzed and identified as oligoglucanes and dextrins. Those are widely applied in food, paper, textile and pharmacological industries. Oligosaccharides are useful as prebiotics as dietary fiber or slowly digestible starch derivatives, and they can be used in form of supplement to certain foodstuffs.