Synthesis of α-hydroxy ketones and vicinal diols with the Bacillus licheniformis DSM 13T butane-2,3-diol dehydrogenase

Enzymatic Cascade in a Simultaneous, One-Pot Approach with In Situ Product Separation for the Asymmetric Production of (4S,5S)-Octanediol

“…1,2-Propanediol was chosen as a cosubstrate since the BlBDH only accepts molecules with two vicinal hydroxyl or carbonyl functions in a molecule as a substrate, and 1,2-propanediol was one of the few diols that the BlBDH oxidizes. 34 Because of this substrate specificity, the BlBDH does not reduce butanal to butanol. This is a huge advantage in our context as it cannot reduce the starting material.…”

“…Catalyst was formulated as lyophilized whole cells (LWC). Genes encoding Ap PDCE469G and Bl BDH (see Supporting Information (SI) for amino acid sequences) were cloned and expressed heterologously in Escherichia coli ( E. coli ) (BL21) in autoinduction medium . The cultures grew for 2 h at 37 °C followed by 48 h at 20 °C before the cells were harvested at 4 °C at 8000 rpm for 45 min.…”

“…33 The resulting (S)-butyroin is reduced to (4S,5S)-octanediol by the butanediol dehydrogenase from Bacillus licheniformis (BlBDH). 34 The NADH of the reduction step is recycled using the same enzyme with 1,2propanediol as cosubstrate by oxidizing 1,2-propanediol to hydroxyacetone (coproduct) (Figure 1). The cascade is designed as a two-step, one-pot, simultaneous enzymatic cascade with both enzymes, the substrate, and 1,2-propanediol present at the beginning.…”

“…The identity of the product and intermediate was determined by commercial racemic standards and based on the known stereoselectivity of the used enzymes for these and similar substrates. 33,34 Description of the Process Concepts. Three developed process concepts for the purification of (4S,5S)-octanediol are presented in the following: The product separation via rectification from aqueous reaction medium (AQ-RECT), rectification from MARS (MARS-RECT) and separation via in situ extraction from aqueous reaction medium and consecutive rectification (BP-RECT).…”

“…The enzymatic two-step cascade starts with a benzoin-type condensation of two butanal molecules catalyzed by a variant of the pyruvate decarboxylase from Acetobacter pasteurianus with a glycine instead of a glutamic acid at position 469 ( Ap PDCE469G) in order to increase the ( S )-selectivity . The resulting ( S )-butyroin is reduced to (4 S ,5 S )-octanediol by the butanediol dehydrogenase from Bacillus licheniformis ( Bl BDH) . The NADH of the reduction step is recycled using the same enzyme with 1,2-propanediol as cosubstrate by oxidizing 1,2-propanediol to hydroxyacetone (coproduct) (Figure ).…”