Oxylipins generation in Lactobacillus helveticus in relation to unsaturated fatty acid supplementation

AimsOxylipins are regarded as unsaturated fatty acids (UFAs) oxidation products, whose accumulation in plants and fungi is associated with stress. The aim of this study was to investigate if a metabolic pathway from UFAs to oxylipins was present also in lactic acid bacteria (LAB). Methods and ResultsA strain of Lactobacillus helveticus, incubated in the presence of oleic, linoleic and linolenic acids released, after 2h, fatty acid oxidation products, mainly C-6, C-8, C-9 aldehydes and alcohols. An experiment with total carbon labelled linoleic acid, in the presence or not of an oxidative stress, demonstrated that oxylipins, such as hexanal, octanal, nonanal, 2-octenal, 2-octanal, originated mainly from the oxidation of this fatty acid. ConclusionsSince lipoxygenase, dioxygenase and cytochrome P450 genes have never been found in L.helveticus, a possible pathway for linoleic conversion and oxylipins formation could include, as a first step, the transient formation of hydroxylated linoleic acids by fatty acids hydratases. However, the sequence of steps from the linoleic acid to the C-6 and C-8 aldehydes needs to be more deeply investigated. Significance and Impact of the StudyDue to the multiple role of oxylipins which are flavouring agents, antimicrobial compounds and interspecific signalling molecules, the knowledge of the mechanisms involved in their biosynthesis in food related bacteria could have an important biotechnological impact, also allowing the overproduction of selected bioactive molecules.