High Levan Production by Bacillus licheniformis NS032 Using Ammonium Chloride as the Sole Nitrogen Source
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АуториKekez, B. D.
Gojgic-Cvijovic, G. D.
Jakovljevic, D. M.
Kojic, J. R. Stefanovic
Markovic, M. D.
Vrvic, M. M.
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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.
Кључне речи:Levan / Box-Behnken design / pH / Bacillus licheniformis / Response surface methodology / Copper / Daphnia magna
Извор:Applied Biochemistry and Biotechnology, 2015, 175, 6, 3068-3083
- Humana Press Inc, Totowa