Biotransformation of prochiral sulfides into (R)-sulfoxides using immobilized Gordonia terrae IEGM 136 cells

• Gordonia cells were immobilized into cryogel of polyvinyl alcohol.
• Immobilized cells showed high tolerance and activity toward prochiral sulfides.
• Immobilized biocatalyst could be reused until fifth cycle.
• Sequential sulfide additions were used to optimize the biotransformation process.
• Putative pathways for sulfide biotransformation by G. terrae IEGM 136 were discussed.

Biotransformation of methyl phenyl sulfide (MPS) into optically active (R)-sulfoxide was optimized using Gordonia terrae IEGM 136 cells immobilized into cryogel of polyvinyl alcohol. Biotransformation time of 0.5 g/L MPS was shortened from 144 to 24 h in comparison with free cells. Immobilized Gordonia cells were resistant to high (up to 1.5 g/L) sulfide concentrations and catalyzed its complete bioconversion into (R)-sulfoxide (95% ee) within 72 h. Using a sequential addition method, the total load of MPS reached 4.25 g/L. At that, MPS bioconversion was 96.9% and the enantiomeric excess (ee) value of the target (R)-sulfoxide was as high as 96%. Possible reuse of immobilized cells for MPS biotransformation was experimentally proved. The obtained biocatalyst showed a high activity towards ethyl phenyl sulfide, benzyl methyl sulfide, methyl p-tolyl sulfide and formed corresponding (R)-sulfoxides with 77–95% ee. Putative pathways for sulfide oxidation by Gordonia cells were proposed.

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