Large-scale production of magnetosomes by chemostat culture of Magnetospirillum gryphiswaldense at high cell density

Microbial Cell Factories

Research

Guo R Li¹  Fang F Guo²  Lun J Li²  Ying Li²  Yang Liu²  Wei Jiang² 

[1] China National Center for Biotechnology Development, 100036, Beijing, China;State Key Laboratories for Agro-biotechnology and College of Biological Sciences, China Agricultural University, 100193, Beijing, China;

关键词: Dissolve Oxygen;    Chemostat Culture;    Sodium Lactate;    Ferric Citrate;    Magnetotactic Bacterium;   

DOI  :  10.1186/1475-2859-9-99

 received in 2010-08-09, accepted in 2010-12-12,  发布年份 2010

来源: Springer

【 摘 要 】

BackgroundMagnetotactic bacteria have long intrigued researchers because they synthesize intracellular nano-scale (40-100 nm) magnetic particles composed of Fe3O4, termed magnetosomes. Current research focuses on the molecular mechanisms of bacterial magnetosome formation and its practical applications in biotechnology and medicine. Practical applications of magnetosomes are based on their ferrimagnetism, nanoscale size, narrow size distribution, dispersal ability, and membrane-bound structure. However, the applications of magnetosomes have not yet been developed commercially, mainly because magnetotactic bacteria are difficult to cultivate and consistent, high yields of magnetosomes have not yet been achieved.ResultsWe report a chemostat culture technique based on pH-stat feeding that yields a high cell density of Magnetospirillum gryphiswaldense strain MSR-1 in an auto-fermentor. In a large-scale fermentor, the magnetosome yield was significantly increased by adjusting the stirring rate and airflow which regulates the level of dissolved oxygen (DO). Low concentration of sodium lactate (2.3 mmol l-1) in the culture medium resulted in more rapid cell growth and higher magnetosome yield than high concentration of lactate (20 mmol l-1). The optical density of M. gryphiswaldense cells reached 12 OD565 nm after 36 hr culture in a 42 L fermentor. Magnetosome yield and productivity were 83.23 ± 5.36 mg l-1 (dry weight) and 55.49 mg l-1 day-1, respectively, which were 1.99 and 3.32 times higher than the corresponding values in our previous study.ConclusionsCompared to previously reported methods, our culture technique with the MSR-1 strain significantly increased cell density, cell yield, and magnetosome yield in a shorter time window and thus reduced the cost of production. The cell density and magnetosome yield reported here are the highest so far achieved with a magnetotactic bacteria. Refinement of this technique will enable further increase of cell density and magnetosome yield.

【 授权许可】

Unknown   
© Liu et al; licensee BioMed Central Ltd. 2010. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.