Background:levo-Menthol is an important flavoring chemical,which can be prepared by enantioselective enzymatic hydrolysis of dl-menthyl esters.A recombinant esterase(BsE)cloned from Bacillus subtilis 0554 shows excell...Background:levo-Menthol is an important flavoring chemical,which can be prepared by enantioselective enzymatic hydrolysis of dl-menthyl esters.A recombinant esterase(BsE)cloned from Bacillus subtilis 0554 shows excellent enantioselectivity to dl-menthyl acetate and has been immobilized using cross-linked enzyme aggregates.Though BsE has relatively high substrate tolerance,the conversion of dl-menthyl acetate decreased sharply with the increase of substrate loading from 1 to 3 M in mono-aqueous system,which might be due to the severe inhibition of enzyme activity at extremely high load of substrate or product.In this work,enzymatic hydrolysis of dl-menthyl acetate with an extremely high load using the immobilized CLEA-BsE was investigated in an organic-aqueous biphasic system containing surfactant to establish a promising bioprocess for large-scale production of l-menthol.Results:An efficient biphasic reaction system of pentanol-water containing sodium dodecyl sulfate(SDS)was developed for improving enantioselective hydrolysis of dl-menthyl acetate to produce l-menthol by immobilized BsE.Under the optimized reaction conditions,l-menthol was produced in>97%enantiomeric excess(ee)at a substrate load of up to 3.0 M with>40%conversion.Conclusions:All the positive features demonstrate the potential applicability of the bioprocess for the large-scale production of l-menthol.展开更多
基金financial supports by the Ministry of Science and Technology,P.R.China(Nos.2011AA02A210 and 2011CB710800)the Open Fund of State Key Laboratory of Bioreactor Engineering(2060204),are gratefully acknowledged.
文摘Background:levo-Menthol is an important flavoring chemical,which can be prepared by enantioselective enzymatic hydrolysis of dl-menthyl esters.A recombinant esterase(BsE)cloned from Bacillus subtilis 0554 shows excellent enantioselectivity to dl-menthyl acetate and has been immobilized using cross-linked enzyme aggregates.Though BsE has relatively high substrate tolerance,the conversion of dl-menthyl acetate decreased sharply with the increase of substrate loading from 1 to 3 M in mono-aqueous system,which might be due to the severe inhibition of enzyme activity at extremely high load of substrate or product.In this work,enzymatic hydrolysis of dl-menthyl acetate with an extremely high load using the immobilized CLEA-BsE was investigated in an organic-aqueous biphasic system containing surfactant to establish a promising bioprocess for large-scale production of l-menthol.Results:An efficient biphasic reaction system of pentanol-water containing sodium dodecyl sulfate(SDS)was developed for improving enantioselective hydrolysis of dl-menthyl acetate to produce l-menthol by immobilized BsE.Under the optimized reaction conditions,l-menthol was produced in>97%enantiomeric excess(ee)at a substrate load of up to 3.0 M with>40%conversion.Conclusions:All the positive features demonstrate the potential applicability of the bioprocess for the large-scale production of l-menthol.
