Aims: Optimal production conditions of conjugated gamma-linolenic acid (CGLA) from gamma-linolenic acid using washed cells of Lactobacillus plantarum AKU 1009a as catalysts were investigated.
Methods and results: 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) alpha-linolenic acid as an inducer. Under the optimal reaction conditions with 13 mg ml(-1)gamma-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.
Conclusion: The practical process of CGLA production from gamma-linolenic acid using washed cells of Lact. plantarum AKU 1009a was successfully established.
Significance and impact of the study: 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.