Effect of bacteria type and sucrose concentration on levan yield and its molecular weight

Microbial Cell Factories

Research

José Mª Sánchez-Álvarez¹  Miguel A. Galán¹  Álvaro González-Garcinuño¹  Antonio Tabernero¹  Eva M. Martin del Valle¹ 

[1] Department of Chemical Engineering, University of Salamanca, Plza. Los Caidos s/n, 37007, Salamanca, Spain;

关键词: Levan;    Molecular weight;    Kinetics;    Byproducts;   

DOI  :  10.1186/s12934-017-0703-z

 received in 2017-01-09, accepted in 2017-05-15,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundLevan has been traditionally produced from microorganism. However, there is a continuous effort in looking for new strains that improve levan production yield and uses alternative sugar sources for growth. Despite having a wide range of data about levan yield, there are not papers which allow controlling molecular weight, and that plays an essential role for further applications.ResultsThe effect of the sucrose concentration on levan yield (and its molecular weight) from Bacillus atrophaeus and Acinetobacter nectaris (Gram positive and Gram negative respectively) was studied in this work. It was found that A. nectaris growth (from 3 to 1.5 g L−1 in 40 h) and its levan production (from 3 to 1.5 g L−1) decreases by increasing sucrose concentration (best results at a concentration of 120 g L−1) whereas B. atrophaeus growth (3.5 g L−1 in 30 h) and its levan production (also 3.5 g L−1) were not affected by modifying that parameter. Levan molecular weight from A. nectaris decreases by increasing sucrose concentration (from 8000 to 2000 kDa) whereas levan molecular weight from B. Atrophaeus remains always around 50 kDa. By performing a kinetic study, it was shown that A. nectaris growth follows a substrate-inhibition model, whereas Monod equation provided a good fit for B. atrophaeus growth. Finally, wastes from orange juice industry were used as a medium culture to cultivate those microorganism, obtaining good results with B. atrophaeus (growth 3 g L−1 in 30 h).ConclusionsLevan production kinetics was determined and compared between different bacteria types.

【 授权许可】

CC BY   
© The Author(s) 2017

【 图 表 】

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