Production of a novel compound, 10,12-dihydroxystearic acid from ricinoleic acid by an oleate hydratase from Lysinibacillus fusiformis

Systematic screening for the biocatalytic hydration of fatty acids from different oily substrates by Elizabethkingia meningoseptica oleate hydratase through a Design-of-experiments approach

The edible plant oils production is associated with the release of different types of by-products. The latter represent cheap and available substrates to produce valuable compounds, such as flavours and fragrances, biologically active compounds and bio-based polymers. Elizabethkingia meningoseptica Oleate hydratases (Em_OhyA) can selectively catalyze the conversion of unsaturated fatty acids, specifically oleic acid, into hydroxy fatty acids, which find different industrial applications. In this study, Design-of-experiment (DoE) strategy was used to screen and identify conditions for reaching high yields in the reaction carried out by Escherichia coli whole-cell carrying the recombinant enzyme Em_OhyA using Waste Cooking Oils (WCO)-derived free fatty acids (FFA) as substrate. The identified reaction conditions for high oleic acid conversion were also tested on untreated triglycerides-containing substrates, such as pomace oil, sunflower oil, olive oil and oil mill wastewater (OMW), combining the triglyceride hydrolysis by the lipase from Candida rugosa and the E. coli whole-cell containing Em_OhyA for the production of hydroxy fatty acids. When WCO, sunflower oil and OMW were used as substrate, the one-pot bioconversion led to an increase of oleic acid conversion compared to the standard reaction. This work highlights the efficiency of the DoE approach to screen and identify conditions for an enzymatic reaction for the production of industrially-relevant products.

Production of mannosylerythritol lipids: biosynthesis, multi-omics approaches, and commercial exploitation

Compilation of resources regarding MEL biosynthesis, key production parameters; available omics resources and current commercial applications, for smut fungi known to produce MELs.

Engineering of an oleate hydratase for efficient C10-Functionalization of oleic acid

Oleate hydratase catalyzes the hydration of unsaturated fatty acids, giving access to C₁₀-functionalization of oleic acid. The resultant 10-hydroxystearic acid is a key material for the synthesis of many biomass-derived value-added products. Herein, we report the engineering of an oleate hydratase from Paracoccus aminophilus (PaOH) with significantly improved catalytic efficiency (from 33 s^-1 mM^-1 to 119 s^-1 mM^-1), as well as 3.4 times increased half-life at 30 °C. The structural mechanism regarding the impact of mutations on the improved catalytic activity and thermostability was elucidated with the aid of molecular dynamics simulation. The practical feasibility of the engineered PaOH variant F233L/F122L/T15 N was demonstrated through the pilot synthesis of 10-hydroxystearic acid and 10-oxostearic acid via an optimized multi-enzymatic cascade reaction, with space-time yields of 540 g L^-1 day^-1 and 160 g L^-1 day^-1, respectively.

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

Oleate hydratases (Ohys, EC 4.2.1.53) are a class of enzymes capable of selective water addition reactions to a broad range of unsaturated fatty acids leading to the respective chiral alcohols. Much research was dedicated to improving the applications of existing Ohys as well as to the identification of undescribed Ohys with potentially novel properties. This study focuses on the latter by exploring the genus Rhodococcus for its plenitude of oleate hydratases. Three different Rhodococcus clades showed the presence of oleate hydratases whereby each clade was represented by a specific oleate hydratase family (HFam). Phylogenetic and sequence analyses revealed HFam-specific patterns amongst conserved amino acids. Oleate hydratases from two Rhodococcus strains (HFam 2 and 3) were heterologously expressed in Escherichia coli and their substrate scope investigated. Here, both enzymes showed a complementary behaviour towards sterically demanding and multiple unsaturated fatty acids. Furthermore, this study includes the characterisation of the newly discovered Rhodococcus pyridinivorans Ohy. The steady-state kinetics of R. pyridinivorans Ohy was measured using a novel coupled assay based on the alcohol dehydrogenase and NAD⁺-dependent oxidation of 10-hydroxystearic acid.

Fatty Acid Hydratases: Versatile Catalysts to Access Hydroxy Fatty Acids in Efficient Syntheses of Industrial Interest

The utilization of hydroxy fatty acids has gained more and more attention due to its applicability in many industrial building blocks that require it, for example, polymers or fragrances. Furthermore, hydroxy fatty acids are accessible from biorenewables, thus contributing to a more sustainable raw material basis for industrial chemicals. Therefore, a range of investigations were done on fatty acid hydratases (FAHs), since these enzymes catalyze the addition of water to an unsaturated fatty acid, thus providing an elegant route towards hydroxy-substituted fatty acids. Besides the discovery and characterization of fatty acid hydratases (FAHs), the design and optimization of syntheses with these enzymes, the implementation in elaborate cascades, and the improvement of these biocatalysts, by way of mutation in terms of the substrate scope, has been investigated. This mini-review focuses on the research done on process development using fatty acid hydratases as a catalyst. It is notable that biotransformations, running at impressive substrate loadings of up to 280 g L−1, have been realized. A further topic of this mini-review is the implementation of fatty acid hydratases in cascade reactions. In such cascades, fatty acid hydratases were, in particular, combined with alcohol dehydrogenases (ADH), Baeyer-Villiger monooxygenases (BVMO), transaminases (TA) and hydrolases, thus enabling access to a broad variety of molecules that are of industrial interest.

On the current role of hydratases in biocatalysis

Water addition to carbon-carbon double bonds provides access to value-added products from inexpensive organic feedstock. This interesting but relatively little-studied reaction is catalysed by hydratases in a highly regio- and enantiospecific fashion with excellent atom economy. Considering that asymmetric hydration of (non-activated) carbon-carbon double bonds is virtually impossible with current organic chemistry, enzymatic hydration reactions are highly attractive for industrial applications. Hydratases have been known for several decades but their biocatalytic potential has only been explored over the past 15 years. As a result, a considerable amount of information on this enzyme group has become available, enabling their development for practical applications. This review focuses on hydratases catalysing water addition to non-activated carbon-carbon double bonds, and examines hydratases from a biochemical, structural and mechanistic angle. Current challenges and opportunities in hydration biocatalysis are discussed, and, ultimately, their potential for organic synthesis is highlighted.

(De)hydratases-recent developments and future perspectives

Hydratases have gained attention as alternative to chemical catalysts for their ability to add and eliminate water with high regio-selectivity, stereo-selectivity and enantio-selectivity. Recently, especially cofactor-independent hydratases came into research focus as they are of particular interest for industrial application. The investigation of the substrate scope as well as mutagenesis studies combined with high-resolution crystal structures and bioinformatic methods shed light on this promising enzyme class. This review presents latest findings in the field of fatty acid hydratases, linalool dehydratase isomerase and carotenoid hydratases focusing on mechanistic und structural aspects as well as the expansion of the substrate scope and new applications in organic synthesis.

Characterization of a designed synthetic autotrophic–heterotrophic consortia for fixing CO2 without light

CO₂ fixation efficiency of the devised synthetic microbial consortia with both autotrophic–autotrophic and autotrophic–heterotrophic microbial interactions were higher than the sum of theoretical CO₂ fixation efficiency of the microbial components.

Stereochemistry of enzymatic water addition to C=C bonds

Water addition to carbon-carbon double bonds using hydratases is attracting great interest in biochemistry. Most of the known hydratases are involved in primary metabolism and to a lesser extent in secondary metabolism. New hydratases have recently been added to the toolbox, both from natural sources or artificial metalloenzymes. In order to comprehensively understand how the hydratases are able to catalyse the water addition to carbon-carbon double bonds, this review will highlight the mechanistic and stereochemical studies of the enzymatic water addition to carbon-carbon double bonds, focusing on the syn/anti-addition and stereochemistry of the reaction.

Production of 5,8-dihydroxy-9,12(Z,Z)-octadecadienoic acid from linoleic acid by whole recombinant Escherichia coli cells expressing diol synthase from Aspergillus nidulans

Diol synthase from Aspergillus nidulans was cloned and expressed in Escherichia coli. Recombinant E. coli cells expressing diol synthase from A. nidulans converted linoleic acid to a product that was identified as 5,8-dihydroxy-9,12(Z,Z)-octadecadienoic acid by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS). The recombinant cells and the purified enzyme showed the highest activity for linoleic acid among the fatty acids tested. The optimal reaction conditions for the production of 5,8-dihydroxy-9,12(Z,Z)-octadecadienoic acid from linoleic acid using whole recombinant E. coli cells expressing diol synthase were pH 7.5, 35°C, 250 rpm, 5 g l(-1) linoleic acid, 23 g l(-1) cells, and 20% (v/v) dimethyl sulfoxide in a 250-ml baffled flask. Under these optimized conditions, whole recombinant cells expressing diol synthase produced 4.98 g l(-1) 5,8-dihydroxy-9,12(Z,Z)-octadecadienoic acid for 150 min without detectable byproducts, with a conversion yield of 99% (w/w) and a productivity of 2.5 g l(-1) h(-1). This is the first report on the biotechnological production of dihydroxy fatty acid using whole recombinant cells expressing diol synthase.