Microbial production of conjugated γ-linolenic acid from γ-linolenic acid by Lactobacillus plantarum AKU 1009a

Optimal production conditions of conjugated γ-linolenic acid (CGLA) from γ-linolenic acid using washed cells of Lactobacillus plantarum AKU 1009a as catalysts were investigated. Washed cells of Lact. plantarum AKU 1009a exhibiting a high level of CGLA productivity were obtained by cultivation in a nutrient medium supplemented with 0·03% (w/v) α-linolenic acid as an inducer. Under the optimal reaction conditions with 13 mg ml⁻¹γ-linolenic acid as a substrate in 5 -ml reaction volume, the washed cells [32% (wet cells, w/v) corresponding to 46 mg ml⁻¹ dry cells] as the catalysts produced 8·8 mg CGLA per millilitre reaction mixture (68% molar yield) in 27 h. The produced CGLA was a mixture of two isomers, i.e., cis-6,cis-9,trans-11-octadecatrienoic acid (CGLA1, 40% of total CGLA) and cis-6,trans-9,trans-11-octadecatrienoic acid (CGLA2, 60% of total CGLA), and accounted for 66% of total fatty acid obtained. The CGLA produced was obtained as free fatty acids adsorbed mostly on the surface of the cells of Lact. plantarum AKU1009a. The practical process of CGLA production from γ-linolenic acid using washed cells of Lact. plantarum AKU 1009a was successfully established. We presented the first example of microbial production of CGLA. CGLA produced by the process is valuable for evaluating their physiological and nutritional effects, and chemical characteristics.