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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