Rainio A, Vahvaselkä M, Laakso S
Helsinki University of Technology, Department of Chemical Technology, Laboratory of Biochemistry and Microbiology, P.O. Box 6100, 02015 HUT, Finland.
Appl Microbiol Biotechnol. 2002 Dec;60(4):481-4. doi: 10.1007/s00253-002-1151-0. Epub 2002 Oct 18.
The microbiological isomerization of linoleic acid (LA) to conjugated linoleic acid (CLA) was studied in resting cell suspensions of a propionibacterium and micellar LA to identify factors critical in the isomerization efficiency. These suspensions, containing cells 5x10(10) colony-forming units ml(-1) and 510 micro g LA ml(-1), isomerized about 90% of LA to CLA. However, the yield was not improved with higher amounts of micellar LA, suggesting that the cells had a fixed capacity to carry out the isomerization. This was explained by the fact that the CLA formed had a tendency to accumulate in the cell mass rather than in the aqueous micellar phase during the isomerization. Concomitantly, cell viability and isomerization rates were gradually reduced. Upon cessation of the reaction, about 46% of all the CLA formed was in the cell material. This accumulation to the cells was prevented by adding the detergent in excess to that required for micellization of LA. Then the cells remained viable, but the rate of isomerization was drastically lowered, due to impaired availability of LA from the fortified micellar phase to the cells. It was concluded that the phase distribution of substrate and product plays a critical role in the microbiological production of CLA.
在丙酸杆菌的静息细胞悬浮液以及胶束态亚油酸（LA）中研究了亚油酸（LA）向共轭亚油酸（CLA）的微生物异构化过程，以确定对异构化效率至关重要的因素。这些悬浮液含有5×10¹⁰菌落形成单位/毫升的细胞和510微克/毫升的LA，可将约90%的LA异构化为CLA。然而，胶束态LA含量更高时产率并未提高，这表明细胞进行异构化的能力是固定的。这可以通过以下事实来解释：在异构化过程中，形成的CLA倾向于在细胞团中积累，而不是在水相胶束相中积累。同时，细胞活力和异构化速率逐渐降低。反应停止后，所有形成的CLA中约46%存在于细胞物质中。通过添加超过LA胶束化所需量的洗涤剂来防止CLA在细胞中的积累。此时细胞仍保持活力，但异构化速率大幅降低，这是由于强化胶束相中LA向细胞的可用性受损。得出的结论是，底物和产物的相分布在CLA的微生物生产中起着关键作用。
