Production of secoisolariciresinol from defatted flaxseed by bacterial biotransformation.
Production of secoisolariciresinol from defatted flaxseed by bacterial biotransformation.
Year: 2012
Authors: Li, M.X. Zhu, H.Y. Yang, D.H. Ma, X.Q. Wang, C.Z. Cai, S.Q. Liu, G.R. Ku, B.S., Liu, S.L.
Publication Name: J Appl Microbiol.
Publication Details: doi:10.1111/j.1365-2672.2012.05436.x
Abstract:
Secoisolariciresinol (SECO) is increasingly recognized for potential clinical application because of its preventive effects against breast and colon cancers, atherosclerosis and diabetes, and its production through biotransformation has been attempted. However, previously reported bacteria all required stringent anaerobic culture conditions, precluding large scale production. Here, we report the isolation and characterization of bacteria that produce SECO under less stringent anaerobic culture conditions. Using defatted flaxseed as raw material, we isolated a facultative anaerobic bacterium from human faeces that hydrolysed secoisolariciresinol diglucoside 3 hydroxy 3 methyl glutaric acid (SDG HMGA) oligomers in flaxseed to produce SECO. Both conventional assays and 16S rRNA gene sequence analysis demonstrated its close relatedness with Bacteroides uniformis. The transformation efficiency of SDG in defatted flaxseed to SECO was more than 80percent by this bacterial strain. We investigated factors that might influence fermentation, such as redox potential and pH, for large-scale fermentation of defatted flaxseed to produce SECO. The method to produce SECO through biotransformation of defatted flaxseed with this bacterial strain is highly efficient and economic. This bacterial strain can transform SDG to SECO under less stringent anaerobic culture conditions, which will greatly facilitate industry-scale production of SECO. (Authors abstract)
Lignans have phyto oestrogenic activities and are effective in the prevention of breast and colon cancers, atherosclerosis and diabetes. Recently, SECO has been found to have a broad range of important biological activities, such as effects in anti-depression and the prevention of breast and colon cancers, atherosclerosis, and diabetes; and SECO is a potent antioxidant. Therefore, efforts have been made to produce SECO from raw materials through biotransformation by bacteria. However, previously reported bacteria that can produce SECO all required stringent anaerobic culture conditions, so large scale production cannot be easily achieved. In this study, defatted flaxseed was used as the raw material to select human intestinal bacteria that can produce SECO through biotransformation under less stringent anaerobic culture conditions. One active bacterial strain was isolated that can transform SDG in flaxseed lignans to SECO. Further the efficiency of transformation from SDG in defatted flaxseed to SECO by this bacterial strain was determined and factors that might influence fermentation, such as redox potential and pH, for large scale fermentation of defatted flaxseed to produce SECO, was investigated.
The defatted flour of flaxseeds contains a content of SDG of 11.7 to 24.1 mg per g in the dry matter. In this study, a bacterial strain that could readily transform the (+) SDG oligomers in defatted flaxseeds to produce valuable active constituents (+) SECO was isolated. The SECO producer e isolated from the microflora of a healthy volunteer was identified to be a bacterial strain closely related to Bact. uniformis based on both API 20A characterization and full length 16S rRNA gene sequence analysis. The conversion ratio of SDG to SECO by ZL1 was more than 80 percent with either defatted flaxseed or pure SDG, demonstrating that the method of bacterial biotransformation is highly efficient for producing SECO from defatted flaxseed. As the effects of SECO production in 5 ml and 2 l culture systems were similar, the biotransformation method may be optimized for possible industrial production. In this study, the configuration of the produced SECO was identified to be of the (+) form. In conclusion, biotransformation by Bacteroides ZL1 could be a very efficient and environmentally friendly way of mass producing (+) SECO from defatted flaxseed. (Editors comments)
