Production of Conjugated Linoleic Acid (CLA) by Lactiplantibacillus plantarum: A Review with Emphasis on Fermented Foods

The term Conjugated Linoleic Acid (CLA) refers generically to a class of positional and geometric conjugated dienoic isomers of linoleic acid. Among the isomers of linoleic acid cis9, trans11-CLA (c9, t11-CLA) and trans10, cis12-CLA (t10, c12-CLA) are found to be biologically active isomers, and they occur naturally in milk, dairy products and meat from ruminants. In addition, some vegetables and some seafoods have also been reported to contain CLA. Although the CLA levels in these natural sources are insufficient to confer the essential health benefits, anti-carcinogenic or anti-cancer effects are of current interest. In the rumen, CLA is an intermediate of isomerization and the biohydrogenation process of linoleic acid to stearic acid conducted by ruminal microorganisms. In addition to rumen bacteria, some other bacteria, such as Propionibacterium, Bifidobacterium and some lactic acid bacteria (LAB) are also capable of producing CLA. In this regard, Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) has demonstrated the ability to produce CLA isomers from linoleic acid by multiple enzymatic activities, including hydration, dehydration, and isomerization. L. plantarum is one of the most versatile species of LAB and the bacterium is widely used in the food industry as a microbial food culture. Thus, in this review we critically analyzed the literature produced in the last ten years with the aim to highlight the potentiality as well as the optimal conditions for CLA production by L. plantarum. Evidence was provided suggesting that the use of appropriate strains of L. plantarum, as a starter or additional culture in the production of some fermented foods, can be considered a critical factor in the design of new CLA-enriched functional foods.