The Influence Of Ionic Liquids On The Characteristics Of Arthrobacter Simplex

In this study, the biotransformation of cortisone acetate (CA) by Arthrobacter simplex (ASP) was selected as a model system for evaluating the influences and material basis of Us on the characteristics of ASP. The transport characteristics of different reaction medium, including [PrMIm]PF6, HP-P-CD, Tween80, hexadecane, was also analyzed.After adding ILs in fermentation culture stage, the growth of bacteria and metabolic ability were declined of varying degrees. Among them, ILs,which side chain alkyl carbon atom number was 2, had smaller influence on bacteria. When the side chain alkyl carbon atom number became 3, the influence on bacteria change greatly, compared with controls, biomass reduced to 54%, sugar metabolism vigor drops to 55%. When the side chains of carbon atoms number>3, bacteria growth was almost completely inhibitted, metabolism ability only remain at around 20%. For the same ILs, the toxicity of bacteria is proportional to the inceeased ILs concentration.With or without ILs pretreatment, compared the process of the 1-en-dehydrogenation of CA in ASP. The cell properties have no obvious change when side chain alkyl carbon atoms number is 2. after pretreatment by [PrMIm]PF6, side chain alkyl carbon atom number is 3, the CA conversion rate increase nearly 10%, besides it has most obvious solubilization effect on the substrate, nearly 2-fold higher than that of control, expressed lower dehydrogenase activity, dropped out 20%, and higher cell permeability, under the dual role of in the solubilization effect and the change of cell characteristics, conversion rate increase significantly.The micrographs performed by TEM illustrated that after being treated by ILs. The cells pre-incubated without ILs had a typical ASP ultrastructure. Cells remained intact, and the cell envelope was complete and clear. When the cells were exposed to 2.5%(v) ILs, the cell envelope became blurred and lost its integrity. Cell permeability is closely related to the integrity of cell membrane. Thus, these alterations may explain the increased permeability of ASP cells.The analysis of lipid composition revealed both a decrease in the proportion of extractable lipids and a considerable shift in fatty acid profile resulting from ILs action. The percentage of loss lipid in cells pre-incubated with ILs was 19.9%, the contents of unsaturated fatty acid was increased by 14.91%, and long-chain fatty acid was reduced by 10.88%.The protein contents of cells pre-incubated with ILs was redused by 10.3%.The SDS-PAGE showed a diffrence of several bands; the analysis of LC-MS/MS revealed that down-regulated of proteins was exist, the function of most down-regulated proteins related to energy production and conversion, meterial transport and metabolism, DNA and recombination, transcription, translation and posttranslational modification.The effect of typical reaction media [PrMIm]PF6, HP-β-CD, Tween80 and hexadecane on the transformation process was studied. Ater treatment by HP-β-CD, the CA conversion rate increased obviously.