A novel enantioselective epoxide hydrolase for (R)-phenyl glycidyl ether to generate (R)-3-phenoxy-1,2-propanediol

Bacillus sp. Z018, a novel strain producing epoxide hydrolase, was isolated from soil. The epoxide hydrolase catalyzed the stereospecific hydrolysis of (R)-phenyl glycidyl ether to generate (R)-3-phenoxy-1,2-propanediol. Epoxide hydrolase from Bacillus sp. Z018 was inducible, and (R)-phenyl glycidyl ether was able to act as an inducer. The fermentation conditions for epoxide hydrolase were 35°C, pH 7.5 with glucose and NH₄Cl as the best carbon and nitrogen source, respectively. Under optimized conditions, the biotransformation yield of 45.8% and the enantiomeric excess of 96.3% were obtained for the product (R)-3-phenoxy-1,2-propanediol.     

Production of (<Emphasis Type="Italic">R</Emphasis>)-ethyl-3,4-epoxybutyrate by newly isolated <Emphasis Type="Italic">Acinetobacter baumannii</Emphasis> containing epoxide hydrolase

Several new microorganisms have been isolated from soil samples with high epoxide hydrolase activity toward ethyl 3,4-epoxybutyrate. Screening was performed by enrichment culture on alkenes as sole carbon source, followed by chiral gas chromatography. Eight strains were discovered with enantioselectivity from moderate to high level and identified as bacterial and yeast species. Cells were cultivated under aerobic condition at 30°C using glucose as carbon source and resting cells were used as biocatalysts for kinetic resolution of ethyl 3,4-epoxybutyrate. Among isolated microorganisms, Acinetobacter baumannii showed highest enantioselectivity for (S)-enantiomer, resulting in (R)-ethyl-3,4-epoxybutyrates (>99%ee, 46% yield). It is the first report on the fact that epoxide hydrolases originating from bacterial species of A. baumannii was applied to kinetic resolution of ethyl 3,4-epoxybutyrate in order to obtain enantiopure high-value-added (R)-ethyl-3,4-epoxybutyrate.     

Epoxide hydrolases from yeasts and other sources: versatile tools in biocatalysis

Major characteristics, substrate specificities and enantioselectivities of epoxide hydrolases from various sources are described. Epoxide hydrolase activity in yeasts is discussed in more detail and is compared with activities in other microorganisms. Constitutively produced bacterial epoxide hydrolases are highly enantioselective in the hydrolysis of 2,2- and 2,3-disubstituted epoxides. A novel bacterial limonene-1,2-epoxide hydrolase, induced by growth on monoterpenes, showed high activities and selectivities in the hydrolysis of several substituted alicyclic epoxides. Constitutively produced epoxide hydrolases are found in eukaryotic microorganisms. Enzymes from filamentous fungi are useful biocatalysts in the resolution of aryl- and substituted alicyclic epoxides. Yeast epoxide hydrolase activity has been demonstrated for the enantioselective hydrolysis of various aryl-, alicyclic- and aliphatic epoxides by a strain of Rhodotorula glutinis. The yeast enzyme, moreover, is capable of asymmetric hydrolysis of meso epoxides and performs highly enantioselective resolution of unbranched aliphatic 1,2-epoxides. Screening for other yeast epoxide hydrolases shows that high enantioselectivity is restricted to a few basidiomycetes genera only. Resolution of very high substrate concentrations is possible by using selected basidiomycetes yeast strains.     

Glacier as a source of novel polyethylene terephthalate hydrolases

Polyethylene terephthalate (PET) is a major component of microplastic contamination globally, which is now detected in pristine environments including Polar and mountain glaciers. As a carbon-rich molecule, PET could be a carbon source for microorganisms dwelling in glacier habitats. Thus, glacial microorganisms may be potential PET degraders with novel PET hydrolases. Here, we obtained 414 putative PET hydrolase sequences by searching a global glacier metagenome dataset. Metagenomes from the Alps and Tibetan glaciers exhibited a higher relative abundance of putative PET hydrolases than those from the Arctic and Antarctic. Twelve putative PET hydrolase sequences were cloned and expressed, with one sequence (designated as GlacPETase) proven to degrade amorphous PET film with a similar performance as IsPETase, but with a higher thermostability. GlacPETase exhibited only 30% sequence identity to known active PET hydrolases with a novel disulphide bridge location and, therefore may represent a novel PET hydrolases class. The present work suggests that extreme carbon-poor environments may harbour a diverse range of known and novel PET hydrolases for carbon acquisition as an environmental adaptation mechanism.     

Rhodococcus erythropolis DCL14 Contains a Novel Degradation Pathway for Limonene

Strain DCL14, which is able to grow on limonene as a sole source of carbon and energy, was isolated from a freshwater sediment sample. This organism was identified as a strain of Rhodococcus erythropolis by chemotaxonomic and genetic studies. R. erythropolis DCL14 also assimilated the terpenes limonene-1,2-epoxide, limonene-1,2-diol, carveol, carvone, and (−)-menthol, while perillyl alcohol was not utilized as a carbon and energy source. Induction tests with cells grown on limonene revealed that the oxygen consumption rates with limonene-1,2-epoxide, limonene-1,2-diol, 1-hydroxy-2-oxolimonene, and carveol were high. Limonene-induced cells of R. erythropolis DCL14 contained the following four novel enzymatic activities involved in the limonene degradation pathway of this microorganism: a flavin adenine dinucleotide- and NADH-dependent limonene 1,2-monooxygenase activity, a cofactor-independent limonene-1,2-epoxide hydrolase activity, a dichlorophenolindophenol-dependent limonene-1,2-diol dehydrogenase activity, and an NADPH-dependent 1-hydroxy-2-oxolimonene 1,2-monooxygenase activity. Product accumulation studies showed that (1S,2S,4R)-limonene-1,2-diol, (1S,4R)-1-hydroxy-2-oxolimonene, and (3R)-3-isopropenyl-6-oxoheptanoate were intermediates in the (4R)-limonene degradation pathway. The opposite enantiomers [(1R,2R,4S)-limonene-1,2-diol, (1R,4S)-1-hydroxy-2-oxolimonene, and (3S)-3-isopropenyl-6-oxoheptanoate] were found in the (4S)-limonene degradation pathway, while accumulation of (1R,2S,4S)-limonene-1,2-diol from (4S)-limonene was also observed. These results show that R. erythropolis DCL14 metabolizes both enantiomers of limonene via a novel degradation pathway that starts with epoxidation at the 1,2 double bond forming limonene-1,2-epoxide. This epoxide is subsequently converted to limonene-1,2-diol, 1-hydroxy-2-oxolimonene, and 7-hydroxy-4-isopropenyl-7-methyl-2-oxo-oxepanone. This lactone spontaneously rearranges to form 3-isopropenyl-6-oxoheptanoate. In the presence of coenzyme A and ATP this acid is converted further, and this finding, together with the high levels of isocitrate lyase activity in extracts of limonene-grown cells, suggests that further degradation takes place via the β-oxidation pathway.     

Substrate specificity and stereospecificity of limonene-1,2-epoxide hydrolase from Rhodococcus erythropolis DCL14; an enzyme showing sequential and enantioconvergent substrate conversion

Limonene-1,2-epoxide hydrolase (LEH) from Rhodococcus erythropolis DCL14, an enzyme involved in the limonene degradation pathway of this microlorganism, has a narrow substrate specificity. Of the compounds tested, the natural substrate, limonene-1,2-epoxide, and several alicyclic and 2-methyl-1,2-epoxides (e.g. 1-methylcyclohexene oxide and indene oxide), were substrates for the enzyme. When LEH was incubated with a diastereomeric mixture of limonene-1,2-epoxide, the sequential hydrolysis of first the (1R,2S)- and then the (1S,2R)-isomer was observed. The hydrolysis of (4R)- and (4S)-limonene-1,2-epoxide resulted in, respectively, (1S,2S,4R)- and (1R,2R,4S)-limonene-1,2-diol as the sole product with a diastereomeric excess of over 98%. With all other substrates, LEH showed moderate to low enantioselectivities (E ratios between 34 and 3).     

Biosynthesis of (R)-phenyl-1,2-ethanediol from racemic styrene oxide by using bacterial and marine fish epoxide hydrolases

Enantio-convergent hydrolysis of racemic styrene oxides was achieved to prepare enantiopure (R)-phenyl-1,2-ethanediol by using two recombinant epoxide hydrolases (EHs) of a bacterium, Caulobacter crescentus, and a marine fish, Mugil cephalus. The recombinant C. crescentus EH primarily attacked the benzylic carbon of (S)-styrene oxide, while the M. cephalus EH preferentially attacked the terminal carbon of (R)-styrene oxide, thus leading to the formation of (R)-phenyl-1,2-ethanediol as the main product. (R)-Phenyl-1,2-ethanediol was obtained with 90% enantiomeric excess and yield as high as 94% from 50 mM racemic styrene oxides in a one-pot process.     

Limonene-1,2-Epoxide Hydrolase from Rhodococcus erythropolis DCL14 Belongs to a Novel Class of Epoxide Hydrolases

An epoxide hydrolase from Rhodococcus erythropolis DCL14 catalyzes the hydrolysis of limonene-1,2-epoxide to limonene-1,2-diol. The enzyme is induced when R. erythropolis is grown on monoterpenes, reflecting its role in the limonene degradation pathway of this microorganism. Limonene-1,2-epoxide hydrolase was purified to homogeneity. It is a monomeric cytoplasmic enzyme of 17 kDa, and its N-terminal amino acid sequence was determined. No cofactor was required for activity of this colorless enzyme. Maximal enzyme activity was measured at pH 7 and 50°C. None of the tested inhibitors or metal ions inhibited limonene-1,2-epoxide hydrolase activity. Limonene-1,2-epoxide hydrolase has a narrow substrate range. Of the compounds tested, only limonene-1,2-epoxide, 1-methylcyclohexene oxide, cyclohexene oxide, and indene oxide were substrates. This report shows that limonene-1,2-epoxide hydrolase belongs to a new class of epoxide hydrolases based on (i) its low molecular mass, (ii) the absence of any significant homology between the partial amino acid sequence of limonene-1,2-epoxide hydrolase and amino acid sequences of known epoxide hydrolases, (iii) its pH profile, and (iv) the inability of 2-bromo-4′-nitroacetophenone, diethylpyrocarbonate, 4-fluorochalcone oxide, and 1,10-phenanthroline to inhibit limonene-1,2-epoxide hydrolase activity.Epoxides are highly reactive compounds which readily react with numerous biological compounds, including proteins and nucleic acids. Consequently, epoxides are cytotoxic, mutagenic, and potentially carcinogenic, and there is considerable interest in biological degradation mechanisms for these compounds.In bacteria, epoxides are formed during the metabolism of alkenes (23) and halohydrins (15, 26, 34, 49). Enzymes belonging to a large number of enzyme classes, including dehydrogenases (17), lyases (21), carboxylases (1, 43), glutathione S-transferases (6, 8), isomerases (24), and hydrolases (7, 19, 44), are involved in the microbial degradation of epoxides.Epoxide hydrolases are enzymes catalyzing the addition of water to epoxides forming the corresponding diol. This group of enzymes has been extensively studied in mammals, while only limited information is available on bacterial epoxide hydrolases. Three functions for epoxide hydrolases are recognized (42). In bacteria, epoxide hydrolases are involved in the degradation of several hydrocarbons, including 1,3-dihalo-2-propanol (34), 2,3-dihalo-1-propanol (15, 26), epichlorohydrin (46), propylene oxide (16), 9,10-epoxy fatty acids (30, 36), trans-2,3-epoxysuccinate (2), and cyclohexene oxide (14). Other epoxide hydrolases, such as microsomal and cytosolic epoxide hydrolase from mammals (for reviews, see references 4, 8, and 44), are involved in the detoxification of epoxides formed due to the action of P-450-dependent monooxygenases (8). Epoxide hydrolases are also involved in biosynthesis of hormones, such as leukotrienes and juvenile hormone (40, 45), and plant cuticular elements (11). Remarkably, the bacterial and eukaryotic epoxide hydrolases described so far form a homogeneous group of enzymes belonging to the α/β-hydrolase fold superfamily (10, 38).Rhodococcus erythropolis DCL14, a gram-positive bacterium, is able to grow on both (+)- and (−)-limonene as the sole source of carbon and energy (47). Cells grown on limonene contained a novel epoxide hydrolase that does not belong to the α/β-hydrolase fold superfamily. This limonene-1,2-epoxide hydrolase converts limonene-1,2-epoxide to limonene-1,2-diol (p-menth-8-ene-1,2-diol [Fig. 1]). In this report, we describe the purification and characterization of this enzyme and show that limonene-1,2-epoxide hydrolase belongs to a novel class of epoxide hydrolases. Open in a separate windowFIG. 1Reaction catalyzed by limonene-1,2-epoxide hydrolase.     

Compositional profile of α / β‐hydrolase fold proteins in mangrove soil metagenomes: prevalence of epoxide hydrolases and haloalkane dehalogenases in oil‐contaminated sites

The occurrence of genes encoding biotechnologically relevant α/β‐hydrolases in mangrove soil microbial communities was assessed using data obtained by whole‐metagenome sequencing of four mangroves areas, denoted BrMgv01 to BrMgv04, in São Paulo, Brazil. The sequences (215 Mb in total) were filtered based on local amino acid alignments against the Lipase Engineering Database. In total, 5923 unassembled sequences were affiliated with 30 different α/β‐hydrolase fold superfamilies. The most abundant predicted proteins encompassed cytosolic hydrolases (abH08; ～ 23%), microsomal hydrolases (abH09; ～ 12%) and Moraxella lipase‐like proteins (abH04 and abH01; < 5%). Detailed analysis of the genes predicted to encode proteins of the abH08 superfamily revealed a high proportion related to epoxide hydrolases and haloalkane dehalogenases in polluted mangroves BrMgv01‐02‐03. This suggested selection and putative involvement in local degradation/detoxification of the pollutants. Seven sequences that were annotated as genes for putative epoxide hydrolases and five for putative haloalkane dehalogenases were found in a fosmid library generated from BrMgv02 DNA. The latter enzymes were predicted to belong to Actinobacteria, Deinococcus‐Thermus, Planctomycetes and Proteobacteria. Our integrated approach thus identified 12 genes (complete and/or partial) that may encode hitherto undescribed enzymes. The low amino acid identity (< 60%) with already‐described genes opens perspectives for both production in an expression host and genetic screening of metagenomes.     

Chemical synthesis and actions of 11,12-thiirano-hepoxilin A3

A novel analog of hepoxilin A3 has been chemically synthesized in which the 11,12-epoxide group has been altered to a thiirano group. This has been accomplished through allylic rearrangement of unnatural (11R,12R)-hepoxilin B₃ under Mitsunobu conditions, first into unnatural (11R,12R)-hepoxilin A₃, followed by conversion of this compound with inversion of the epoxide centers into the thiirano-hepoxilin A₃ having the natural 11S,12S configuration. We also report herein evidence showing that thiirano-hepoxilin A₃ raises intracellular calcium concentrations in intact human neutrophils.     

Localization of the human soluble epoxide hydrolase gene (EPHX2) to chromosomal region 8p21-p12

Epoxide hydrolases have an important function in organisms in that they catalyze the transformation of potentially toxic or carcinogenic epoxides into the corresponding diols. In this study, the chromosomal localization was determined for the human gene encoding soluble epoxide hydrolase. A polymerase chain reaction fragment corresponding to the C-terminal region of the mouse protein was used to isolate a cosmid clone from a human genomic library. By fluorescence in situ hybridization to metaphase chromosomes, the soluble epoxide hydrolase gene was then localized to chromosomal region 8p21-p12.     

Biochemical and structural characterization of a novel cold-active esterase-like protein from the psychrophilic yeast Glaciozyma antarctica

Dienelactone hydrolase, an α/β hydrolase enzyme, catalyzes the hydrolysis of dienelactone to maleylacetate, an intermediate for the Krebs cycle. Genome sequencing of the psychrophilic yeast, Glaciozyma antarctica predicted a putative open reading frame (ORF) for dienelactone hydrolase (GaDlh) with 52% sequence similarity to that from Coniophora puteana. Phylogenetic tree analysis showed that GaDlh is closely related to other reported dienelactone hydrolases, and distantly related to other α/β hydrolases. Structural prediction using MODELLER 9.14 showed that GaDlh has the same α/β hydrolase fold as other dienelactone hydrolases and esterase/lipase enzymes, with a catalytic triad consisting of Cys–His–Asp and a G–x–C–x–G–G motif. Based on the predicted structure, GaDlh exhibits several characteristics of cold-adapted proteins such as glycine clustering in the binding pocket, reduced protein core hydrophobicity, and the absence of proline residues in loops. The putative ORF was amplified, cloned, and overexpressed in an Escherichia coli expression system. The recombinant protein was overexpressed as soluble proteins and was purified via Ni–NTA affinity chromatography. Biochemical characterization of GaDlh revealed that it has an optimal temperature at 10 °C and that it retained almost 90% of its residual activity when incubated for 90 min at 10 °C. The optimal pH was at pH 8.0 and it was stable between pH 5–9 when incubated for 60 min (more than 50% residual activity). Its K_m value was 256 μM and its catalytic efficiency was 81.7 s⁻¹. To our knowledge, this is the first report describing a novel cold-active dienelactone hydrolase-like protein.

     

Isolation and identification of a novel Rhodococcus sp. ML-0004 producing epoxide hydrolase and optimization of enzyme production

Rhodococcus sp. ML-0004, a novel strain for producing epoxide hydrolase, was isolated from soil in this study. The epoxide hydrolase can catalyze the stereo-specific hydrolysis of cis-epoxysuccinic acid to generate l(+)-tartaric acid. By examining physiological, biochemical characteristics and comparing its 16S rDNA gene sequence, it was identified as Rhodococcus opacus, and named R. opacus ML-0004. The optimal conditions for epoxide hydrolase production from R. opacus ML-0004 were also investigated. Propanediol and (NH₄)₂SO₄ were selected as carbon source and nitrogen source, respectively, for the production of R. opacus ML-0004 epoxide hydrolase. The optimal conditions for epoxide hydrolase production were fermentation temperature = 28 °C, pH 7.0, and cultivation time = 26 h. Under these conditions, the maximum epoxide hydrolase activity reached 10.5 U mL⁻¹.     

Diversity and biocatalytic potential of epoxide hydrolases identified by genome analysis

Epoxide hydrolases play an important role in the biodegradation of organic compounds and are potentially useful in enantioselective biocatalysis. An analysis of various genomic databases revealed that about 20% of sequenced organisms contain one or more putative epoxide hydrolase genes. They were found in all domains of life, and many fungi and actinobacteria contain several putative epoxide hydrolase-encoding genes. Multiple sequence alignments of epoxide hydrolases with other known and putative alpha/beta-hydrolase fold enzymes that possess a nucleophilic aspartate revealed that these enzymes can be classified into eight phylogenetic groups that all contain putative epoxide hydrolases. To determine their catalytic activities, 10 putative bacterial epoxide hydrolase genes and 2 known bacterial epoxide hydrolase genes were cloned and overexpressed in Escherichia coli. The production of active enzyme was strongly improved by fusion to the maltose binding protein (MalE), which prevented inclusion body formation and facilitated protein purification. Eight of the 12 fusion proteins were active toward one or more of the 21 epoxides that were tested, and they converted both terminal and nonterminal epoxides. Four of the new epoxide hydrolases showed an uncommon enantiopreference for meso-epoxides and/or terminal aromatic epoxides, which made them suitable for the production of enantiopure (S,S)-diols and (R)-epoxides. The results show that the expression of epoxide hydrolase genes that are detected by analyses of genomic databases is a useful strategy for obtaining new biocatalysts.     

Cloning and characterization of an epoxide hydrolase from <Emphasis Type="Italic">Novosphingobium aromaticivorans</Emphasis>

A gene encoding a putative epoxide hydrolase (EHase) was identified by analyzing an open reading frame of the genome sequence of Novosphingobium aromaticivorans, retaining the conserved catalytic residues such as the catalytic triad (Asp177, Glu328, and His355) and the oxyanion hole. The enantioselective EHase gene (neh) was cloned, and the recombinant EHase could be purified to apparent homogeneity by one step of metal affinity chromatography and further characterized. The purified N. aromaticivorans enantioselective epoxide hydrolase (NEH) showed enantioselective hydrolysis toward styrene oxide, glycidyl phenyl ether, epoxybutane, and epichlorohydrin. The optimal EHase activity toward styrene oxide occurred at pH 6.5 and 45°C. The purified NEH could preferentially hydrolyze (R)-styrene oxide with enantiomeric excess of more than 99% and 11.7% yield after 20-min incubation at an optimal condition. The enantioselective hydrolysis of styrene oxide was also confirmed by the analysis of the vicinal diol, 1-phenyl-1,2-ethanediol. The hydrolyzing rates of the purified NEH toward epoxide substrates were not affected by as high as 100 mM racemic styrene oxide.     

Cloning,expression and enantioselective hydrolytic catalysis of a microsomal epoxide hydrolase from a marine fish, <Emphasis Type="Italic">Mugil cephalus</Emphasis>

The cDNA of a marine fish microsomal epoxide hydrolase (mEH) gene from Mugil cephalus was cloned by rapid amplification of cDNA ends (RACE) techniques. The homology model for the mEH of M. cephalus showed a characteristic structure of α/β-hydrolase-fold main domain with a lid domain over the active site. The characteristic catalytic triad, consisting of Asp(238), His(444), and Glu(417), was highly conserved. The cloned mEH gene was expressed in Escherichia coli and the recombinant mEH exhibited (R)-preferred hydrolysis activity toward racemic styrene oxide. We obtained enantiopure (S)-styrene oxide with a high enantiopurity of more than 99% enantiomeric excess and yield of 15.4% by batch kinetic resolution of 20 mM racemic styrene oxide.     

Pro-antibiotic Substrates for the Identification of Enantioselective Hydrolases

A new growth-based screening method for the identification of enantioselective hydrolases, such as lipases and esterases, using pro-antibiotic substrates was devised. An enantioselective hydrolase could be identified by measuring growth rates of cells in liquid media containing (R)- or (S)-2–phenylbutyric chloramphenicol esters. This method can be applied to the screening of novel enantioselective microbes and to the high-throughput screening for the directed evolution of enantioselective hydrolytic enzymes.     

Cloning and characterization of three epoxide hydrolases from a marine bacterium, <Emphasis Type="Italic">Erythrobacter litoralis</Emphasis> HTCC2594

Previously, we reported that ten strains belonging to Erythrobacter showed epoxide hydrolase (EHase) activities toward various epoxide substrates. Three genes encoding putative EHases were identified by analyzing open reading frames of Erythrobacter litoralis HTCC2594. Despite low similarities to reported EHases, the phylogenetic analysis of the three genes showed that eeh1 was similar to microsomal EHase, while eeh2 and eeh3 could be grouped with soluble EHases. The three EHase genes were cloned, and the recombinant proteins (rEEH1, rEEH2, and rEEH3) were purified. The functionality of purified proteins was proved by hydrolytic activities toward styrene oxide. EEH1 preferentially hydrolyzed (R)-styrene oxide, whereas EEH3 preferred to hydrolyze (S)-styrene oxide, representing enantioselective hydrolysis of styrene oxide. On the other hand, EEH2 could hydrolyze (R)- and (S)-styrene oxide at an equal rate. The optimal pH and temperature for the EHases occurred largely at neutral pHs and 40–55 °C. The substrate selectivity of rEEH1, rEEH2, and rEEH3 toward various epoxide substrates were also investigated. This is the first representation that a strict marine microorganism possessed three EHases with different enantioselectivity toward styrene oxide.     

Isolation and identification of sapotexanthin 5,6-epoxide and 5,8-epoxide from red mamey (Pouteria sapota)

Two new carotenoids, sapotexanthin 5,6-epoxide and sapotexanthin 5,8-epoxide, have been isolated from the ripe fruits of red mamey (Pouteria sapota). Sapotexanthin 5,6-epoxide was also prepared by partial synthesis via epoxidation of sapotexanthin, and the (5R,6S) and (5S,6R) stereoisomers were identified by high-performance liquid chromatography–electronic circular dichroism (HPLC-ECD) analysis. Spectroscopic data of the natural and semisynthetic derivatives obtained by acid-catalyzed rearrangement of cryptocapsin 5,8-epoxide stereoisomers were compared for structural elucidation.     

Identification and characterization of epoxide hydrolase activity of polycyclic aromatic hydrocarbon-degrading bacteria for biocatalytic resolution of racemic styrene oxide and styrene oxide derivatives

A novel epoxide hydrolase (EHase) from polycyclic aromatic hydrocarbon (PAH)-degrading bacteria was identified and characterized. EHase activity was identified in four strains of PAH-degrading bacteria isolated from commercial gasoline and oil-contaminated sediment based on their growth on styrene oxide and its derivatives, such as 2,3- and 4-chlorostyrene oxides, as a sole carbon source. Gordonia sp. H37 exhibited high enantioselective hydrolysis activity for 4-chlorostyrene oxide with an enantiomeric ratio of 27. Gordonia sp. H37 preferentially hydrolyzed the (R)-enantiomer of styrene oxide derivatives resulting in the preparation of a (S)-enantiomer with enantiomeric excess greater than 99.9 %. The enantioselective EHase activity was identified and characterized in various PAH-degrading bacteria, and whole cell Gordonia sp. H37 was employed as a biocatalyst for preparing enantiopure (S)-styrene oxide derivatives.