The Fatty-Acid Hydratase Activity of the Most Common Probiotic Microorganisms

Abstract

In this work, we studied the biotechnological potential of thirteen probiotic microorganisms currently used to improve human health. We discovered that the majority of the investigated bacteria are able to catalyze the hydration reaction of the unsaturated fatty acids (UFAs). We evaluated their biocatalytic activity toward the three most common vegetable UFAs, namely oleic, linoleic, and linolenic acids. The whole-cell biotransformation experiments were performed using a fatty acid concentration of 3 g/L in anaerobic conditions. Through these means, we assessed that the main part of the investigated strains catalyzed the hydration reaction of UFAs with very high regio- and stereoselectivity. Our biotransformation reactions afforded almost exclusively 10-hydroxy fatty acid derivatives with the single exception of Lactobacillus acidophilus ATCC SD5212, which converted linoleic acid in a mixture of 13-hydroxy and 10-hydroxy derivatives. Oleic, linoleic, and linolenic acids were transformed into (R)-10-hydroxystearic acid, (S)-(12Z)-10-hydroxy-octadecenoic, and (S)-(12Z,15Z)-10-hydroxy-octadecadienoic acids, respectively, usually with very high enantiomeric purity (ee > 95%). It is worth noting that the biocatalytic capabilities of the thirteen investigated strains may change considerably from each other, both in terms of activity, stereoselectivity, and transformation yields. Lactobacillus rhamnosus ATCC 53103 and Lactobacillus plantarum 299 V proved to be the most versatile, being able to efficiently and selectively hydrate all three investigated fatty acids.

Bacterial Biotransformation of Oleic Acid: New Findings on the Formation of γ-Dodecalactone and 10-Ketostearic Acid in the Culture of Micrococcus luteus

“…However, some studies describe hydratase activity in yeast [27,31], and this fact has been questioned recently [32]. Our studies on the potential yeast-mediated hydration of oleic acid (1) confirmed also that Saccharomyces species do not possess hydratase activity [33,34]. Bacterial contaminants of commercial baker's yeast are responsible for the stereoselective conversion of oleic acid (1) into 10-hydroxystearic acid (2).…”

Oleate Hydratase from Lactobacillus rhamnosus ATCC 53103: A FADH2-Dependent Enzyme with Remarkable Industrial Potential

“…These biochemical transformations were discovered in the early 1960s, during a study on the hydration of oleic acid (Figure 1) using a Pseudomonas strain [6,7]. Afterwards, a number of other microorganisms proved to be able to perform this transformation [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] but the enzymes responsible for the hydration step (oleate hydratases) have been characterized only recently [24]. Oleate hydratases (OLH, EC 4.2.1.53) convert oleic acid (OA) into (R)-10-hydroxystearic acid (10-HSA) [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39], a high value commercial molecule due to its potential application as surfactant, lubricant, additive in cosmetics industries, and as a starting material in polymer and flavor chemistry.…”

“…Being involved in a research project aimed at the valorization of the vegetable oils waste, we studied the biocatalytic hydration of the latter fatty acids using both microbial transformations [21][22][23] and isolated hydratase [26]. In this context, we demonstrated the versatility of the probiotic bacteria Lactobacillus rhamnosus ATCC 53103 [22], which is able to hydrate oleic, linoleic, and linolenic acid affording (R)-10-hydroxystearic acid, (S)-(12Z)-10-hydroxy-octadecenoic acid, and (S)-(12Z,15Z)-10-hydroxy-octadecadienoic acid, respectively, in very high enantiomeric purity (ee > 95%), without the formation of other regioisomers or polyhydroxylated fatty acids.…”

“…Concerning the hydratase activity of strains belonging to the Lactobacillus genus, we observed that the transformation of UFAs into HFAs can be properly accomplished using anaerobic conditions and adding the suitable UFA during the exponential phase of growth [22,23]. According to Lactobacillus metabolism, these conditions lead to the production of the reduced forms of nicotinamide adenine dinucleotide (NADH) or nicotinamide adenine dinucleotide phosphate (NADPH), which, in absence of oxygen, lower the oxidation-reduction potential of the medium.…”

Exploring the abundance of oleate hydratases in the genus Rhodococcus—discovery of novel enzymes with complementary substrate scope

“…Oleate hydratase (Ohy) belongs to the first group acting on isolated double bonds in fatty acids e.g. oleic acid to produce 10-hydroxystearic acid (Scheme 1) (Demming et al 2018;Engleder and Pichler 2018;Serra et al 2020). Up until now, all characterised Ohys are FAD-dependent.…”