title: High levan production by Bacillus licheniformis NS032 using ammonium chloride as the sole nitrogen source.
abstract: In this study, levan production by Bacillus licheniformis NS032 isolated from a petroleum sludge sample was investigated. High levan yield was obtained in a wide range of sucrose concentrations (up to 400 g/L) and, contrary to most levan-producing strains, using ammonium chloride as the sole N source. Interaction between sucrose, ammonium chloride, and initial pH of the medium in a low sucrose (60-200 g/L) and a high sucrose (300-400 g/L) system was analyzed by response surface methodology. According to the calculated model in the low sucrose system, maximum predicted levan yield was 47.8 g/L (sucrose 196.8 g/L, ammonium chloride 2.4 g/L, pH 7.0), while in the high sucrose system, levan yield was 99.2 g/L (sucrose 397.6 g/L, ammonium chloride 4.6 g/L, pH 7.4). In addition, protective effect of microbial levan against copper toxicity to Daphnia magna is observed for the first time. The acute toxicity (48 h EC50) of copper decreased from 0.14 to 0.44 mg/L by levan in concentration of 50 ppm.
authors.affiliation: Faculty of Chemistry, University of Belgrade, Studentski trg 12-16, P.O. Box 51, Belgrade, 11000, Serbia.
authors.forename: B D
authors.initials: BD
authors.lastname: Kekez
authors.forename: G D
authors.initials: GD
authors.lastname: Gojgic-Cvijovic
authors.forename: D M
authors.initials: DM
authors.lastname: Jakovljevic
authors.forename: J R
authors.initials: JR
authors.lastname: Stefanovic Kojic
authors.forename: M D
authors.initials: MD
authors.lastname: Markovic
authors.forename: V P
authors.initials: VP
authors.lastname: Beskoski
authors.forename: M M
authors.initials: MM
authors.lastname: Vrvic
mesh_terms: D000643:Ammonium Chloride / Q000378:metabolism*; D001407:Bacillus / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D005285:Fermentation; D005630:Fructans / Q000378:metabolism*; D013395:Sucrose / Q000378:metabolism
chemical_list: D005630:Fructans; D000643:Ammonium Chloride; D013395:Sucrose; C072599:levan