Short Communication Simple Preparation of Rhodococcus erythropolis DSM 44534 as Biocatalyst to Oxidize Diols into the Optically Active Lactones ENRIQUETA MARTINEZ-ROJAS, 1 TERESA OLEJNICZAK, 2 KONRAD NEUMANN, 3 LEIF-ALEXANDER GARBE 1,3 AND FILIP BORATYÑSKI 2 * 1 Neubrandenburg University of Applied Sciences, Neubrandenburg, Germany 2 Department of Chemistry, University of Environmental and Life Sciences, Wroclaw, Poland 3 Department of Biotechnology, TU Berlin, Bioanalytics GG6, Berlin, Germany ABSTRACT In the current study, we present a green toolbox to produce ecological com- pounds like lactone moiety. Rhodococcus erythropolis DSM 44534 cells have been used to oxidize both decane-1,4-diol (2a) and decane-1,5-diol (3a) into the corresponding γ-(2b) and δ- decalactones (3b) with yield of 80% and enantiomeric excess (ee) = 75% and ee = 90%, respec- tively. Among oxidation of meso diols, (À)-(1S,5R)-cis-3-oxabicyclo[4.3.0]non-7-en-2-one (5a) with 56% yield and ee = 76% as well as (À)-(2R,3S)-cis-endo-3-oxabicyclo[2.2.1]dec-7-en-2-one (6a) with 100% yield and ee = 90% were formed. It is worth mentioning that R. erythropolis DSM 44534 grew in a mineral medium containing ethanol as the sole source of energy and carbon Chirality 00:000–000, 2016. © 2016 Wiley Periodicals, Inc. KEY WORDS: Bacteria; diols; lactones; oxidation; Rhodococcus erythropolis DSM 44534; stereoselectivity The biological properties of chiral compounds are often strongly related to the absolute configuration. Therefore, looking for new stereoselective methods to synthesize opti- cally pure molecules with various biological activities is one of the most studied areas in current chemistry. Lactones are widespread natural products, which exhibit a wide spectrum of biological activities such as antimicrobial, antioxidant, and anticancer. 1–3 Furthermore, lactone moieties have been found as natural ingredients in different enantiomeric compo- sitions used in the essences and fragrances industry. 4 Although the organocatalytic methods of lactonization of diols with application of toxic metal complexes under extreme experimental conditions are still applied, 5–8 the use of biocatalysts has considerably increased in the preparation of enantiomerically pure or enriched lactones under mild and non- toxic conditions. Biotransformations are carried out under mild temperature, pH, and pressure conditions and their most signif- icant advantages are high chemo-, regio-, and stereoselectivity. In the literature, different microbial/enzymatic methods of lactone biosynthesis were presented. 9–14 A chemoenzymatic route with application of modified lipase from Pseudomonas sp. in order to catalyze a stereoselective acylation of 5- hydroxy acid esters and subsequent lactonization into opti- cally active lactones has been optimized. 13 Reduction of car- bonyl groups in γ- and δ-ketoacids or ketoesters as well as lactonization process was catalyzed by different species of yeast. 15 Hydrolytic dehalogenation of bis(4-chloro-n-butyl) ether with Rhodococcus erythropolis DSM 44354 afforded γ- butyrolactone as a major metabolite and 1,4-butanediol as well as γ-butyrolactol as intermediate products. 16 Also worth mentioning is the biooxidative methods in lac- tone synthesis. Microbial Baeyer-Villiger oxidation with appli- cation of whole cell cultures in the synthesis of lactones from α- and β-thujone was successfully applied. 17 Biooxidation of 1- alkylbutane-1,4-diols into the corresponding γ-lactones by whole cells of Acetobacter aceti contributed to drospirenon production. 18 A native as well as a recombinant alcohol dehy- drogenase from horse liver (HLADH) has been broadly used in the oxidation of racemic 1,4-diols, 19 1,5- and 1,6-diols, 12 as well as meso diols 20 into the enantiomerically enriched lac- tones. Recently, commercially available HLADH has also been used for the desymmetrization oxidation of diols by adding organic cosolvents to prepare lactones with enantio- meric excess (ee) and improved yield. 21 In our previous work, it was observed that decane-1,4-diol as well as nonane-1,4-diol were converted by R. erythropolis DSM 44354 into optically active γ-R-decalactone and γ-R- nonalactone, respectively. 22 Additionally, the oxidation pro- cess of meso diols possessing monocyclic and bicyclic struc- tures into corresponding chiral lactones by R. erythropolis DSM 44354 was established during the microbial alcohol de- hydrogenase screening. 23 Herein we report an optimized pro- tocol for the oxidation of racemic aliphatic diols as well as meso cyclic diols into the corresponding lactone products using whole cells of R. erythropolis DSM 44354 as biocatalyst. MATERIALS AND METHODS Strain and Cultivation Conditions R. erythropolis DSM 44534 was obtained from the German Collection of Microorganisms (DSMZ, Braunschweig, Germany). The biomass pro- duction was performed as follows: R. erythropolis cells were grown for 5 days at 28 °C in shake flasks containing mineral medium supplemented Contract grant sponsor: National Science Centre; Contract grant number: 2011/03/B/NZ9/05005. *Correspondence to: Filip Boratyñski, Department of Chemistry, University of Environmental and Life Sciences, Norwida 25, 50-375, Wrocław, Poland. E- mail: filip.boratynski@up.wroc.pl Received for publication 31 December 2015; Accepted 24 June 2016 DOI: 10.1002/chir.22623 Published online in Wiley Online Library (wileyonlinelibrary.com). © 2016 Wiley Periodicals, Inc. CHIRALITY (2016)