Levan from Leuconostoc citreum BD1707: production optimization and changes in molecular weight distribution during cultivation

作者：Jin Han, Huafeng Feng, Xiaohua Wang, Zhenmin Liu, Zhengjun Wu · 发表于：BMC Biotechnology · 年份：2021 · DOI：10.1186/s12896-021-00673-y · 被引用次数：36 · 研究领域：Microbial Metabolites in Food Biotechnology、Diet, Metabolism, and Disease、Polysaccharides and Plant Cell Walls

Abstract Background Levan is a well-known homopolymer of fructose composed predominantly of β-(2, 6) fructofuranosyl linkages in the backbone with occasional β-(2, 1) linkages in the branch chains with varied applications. However, high production cost due to low yield of microbial levan has become a bottleneck for its practical applications. Furthermore, factors affecting the molecular mass of the synthesized levan by Leuconostoc spp. during prolonged cultivation is not fully elucidated. Methods The cultivation condition for Leuconostoc citreum BD1707 to synthesize levan was optimized by single-factor experiments and subsequently with response surface methodology (RSM). The average molecular weight (Mw) of levan synthesized by the strain L.citreum BD1707 under the optimized cultivation conditions was monitored by high-performance size exclusion chromatography (HPSEC). Finally, the enzyme with levan-degrading activity was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Results The levan yield of BD1707 reached 34.86 g/L with a corresponding productivity of 7.47 g/L/d under the optimal cultivation conditions deduced by RSM, i.e., cultivation at 26 °C and 200 rpm for 112 h in tomato juice supplemented with 172 g/L sucrose with an initial pH value of 6.12. The Mw of levan reached a peak value of 2.320 × 10 7 Da at 6 h of cultivation under the optimized cultivation conditions and then gradually decreased to 8.809 × 10 6 Da after 120 h of cultiv...