title: Purification and biochemical characterization of a novel thermostable lichenase from Aspergillus niger US368.
abstract: New β-1,3;1,4-glucanase was purified from Aspergillus niger US368. The pure glucanase has a molecular mass of about 32 kDa. The N-terminal sequence of the purified enzyme (A-G-T-N-P-P-I-G-V) was determined. The optimum pH and temperature recorded for enzyme activity were 5 and 60 °C, respectively. It also displayed marked thermostability with a half-life of 30 min at 70 °C. At 37 °C, the enzyme showed 100% stability from pH 3 to 10. The Km and Vmax values exhibited by the enzyme on barley β-glucan were 0.62 mg ml(-1) and 34.46 U ml(-1), respectively. The enzyme is a retaining-one and was only active toward glucan containing β-1,3;1,4-linkages. The production of β-glucanase with barley flour as the sole carbon source was optimized. This is the first report on the purification and characterization of a β-1,3;1,4-glucanase from A. niger. This lichenase could be considered as a candidate for future application particularly in the animal feed industry.
authors.affiliation: Laboratoire de Microorganismes et de Biomolécules (LMB), Centre de Biotechnologie de Sfax (CBS), Université de Sfax, Route de Sidi Mansour Km 6, BP 1177 3018 Sfax, Tunisia.
authors.forename: Fatma
authors.initials: F
authors.lastname: Elgharbi
authors.forename: Aïda
authors.initials: A
authors.lastname: Hmida-Sayari
authors.forename: Mouna
authors.initials: M
authors.lastname: Sahnoun
authors.forename: Radhouane
authors.initials: R
authors.lastname: Kammoun
authors.forename: Lobna
authors.initials: L
authors.lastname: Jlaeil
authors.forename: Hajer
authors.initials: H
authors.lastname: Hassairi
authors.forename: Samir
authors.initials: S
authors.lastname: Bejar
mesh_terms: D000595:Amino Acid Sequence; D000821:Animal Feed; D001234:Aspergillus niger / Q000201:enzymology*; D055598:Chemical Phenomena; D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007221:Industry; D007700:Kinetics; D008670:Metals / Q000494:pharmacology; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D008670:Metals; D006026:Glycoside Hydrolases; C028020:licheninase
keywords: Aspergillus niger US368; Statistical experimental designs; Thermostability; β-1,3 ;1,4-Glucanase