Conjugated fatty acids have attracted much attention as a novel type of biologically beneficial functional lipid. Some isomers of conjugated linoleic acid (CLA) reduce carcinogenesis, ...atherosclerosis, and body fat. Considering the use of CLA for medicinal and nutraceutical purposes, a safe isomer-selective process is required. The introduction of biological reactions for CLA production could be an answer. We screened microbial reactions useful for CLA production, and found several unique reactions in lactic acid bacteria. Lactic acid bacteria produced CLA from linoleic acid. The produced CLA comprised a mixture of
cis-9,
trans-11-octadecadienoic acid (18:2) and
trans-9,
trans-11-18:2.
Lactobacillus plantarum AKU 1009a was selected as a potential CLA producer. Using washed cells of
L. plantarum AKU 1009a as a catalyst, CLA production from linoleic acid reached 40 mg/ml under the optimized conditions. The CLA-producing reaction was found to consist of two successive reactions,
i.e., hydration of linoleic acid to 10-hydroxy-12-octadecenoic acid and dehydrating isomerization of the hydroxy fatty acid to CLA. On the basis of these results, the transformation of hydroxy fatty acids by lactic acid bacteria was investigated. Lactic acid bacteria transformed ricinoleic acid (12-hydroxy-
cis-9-octadecenoic acid) to CLA (a mixture of
cis-9,
trans-11-18:2 and
trans-9,
trans-11-18:2). Castor oil, which is rich in the triacylglycerol form of ricinoleic acid, was also found to act as a substrate for CLA production by lactic acid bacteria with the aid of lipase-catalyzed triacylglycerol hydrolysis.
L. plantarum AKU 1009a produced conjugated trienoic fatty acids from α- and γ-linolenic acid. The trienoic fatty acids produced from α-linolenic acid were identified as
cis-9,
trans-11,
cis-15-octadecatrienoic acid (18:3) and
trans-9,
trans-11,
cis-15-18:3. Those produced from γ-linolenic were
cis-6,
cis-9,
trans-11-18:3 and
cis-6,
trans-9,
trans-11-18:3. The conjugated trienoic fatty acids produced from α- and γ-linolenic acid were further saturated by
L. plantarum AKU 1009a to
trans-10,
cis-15-18:2 and
cis-6,
trans-10-18:2, respectively.
Ricinoleic acid (12-hydroxy-cis-9-octadecaenoic acid) was an effective substrate for conjugated linoleic acid (CLA) production by washed cells of Lactobacillus plantarum AKU 1009a. The CLA produced ...was a mixture of cis-9,trans-11- and trans-9,trans-11-octadecadienoic acids. Addition of α-linolenic acid to the culture medium increased the CLA productivity of the washed cells. In the presence of lipase, castor oil, in which the main fatty acid component is ricinoleic acid, also was a substrate for CLA.
An isomer of the conjugated linoleic acid (CLA) produced from linoleic acid by Lactobacillus plantarum was identified as cis-9,trans-11-octadecadienoic acid by proton nuclear magnetic resonance ...spectroscopy. Together with earlier results, we concluded that the bacterium produces two CLA isomers, cis-9,trans-11- and trans-9,trans-11-octadecadienoic acid from linoleic acid. The addition of L-serine, glucose, AgNO
3
, or NaCl to the reaction mixture reduced production of the latter.
Bioprocesses, which involve biocatalysts for the production of useful compounds, are expected to become a leading player in green chemistry. The first step in bioprocess development is screening for ...useful biological reactions in the immense number of microorganisms with infinite diversity and versatility. This review introduces some examples of bioprocess development that started from process design stemming from the discovery of unique metabolic processes, reactions, and enzymes in microbial nucleic acid and lipid metabolisms.
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