The Influence Of New Ionic Liquids On The Cytotoxicity Of Arthrobacter Simplex And Biocatalysis Of Cholesterol

Deep eutectic solvents(DESs),being a new,inexpensive and environment-friendly type of ionic liquids,have currently attracted widespread academic and industrial interest.Application of DES in biotransformation system has made important achievement.DESs are generally regarded as "green solvents" because they complsed of ammonium salts and H-bond donors(HBD),which are considered to be eco-friendly.But their effects on whole cell and whole cell biotransformation.In this study,DESs,prepared by mixing cholinium chloride(ChCl)with three H-bond donors(HBDs)(urea,glycerol,ethylene glycol)at different molar ratios,was used as co-solvent in the cholesterol biotransformation by A.simplex.A systematical investigation of the effect of DESs on the cholesterol solubility and biological catalysis as well as the cytotoxicity of A.simplex was carried out to elucidate the law of DESs on the bio transformation of cholesterol using A.simplex.The effect of DESs on A.simplex was investigated by analysis of the cell growth curve,glucose consumption and cell viability.The toxicity of DESs on the strain,being positive correlation with the mole of HBD,increased with the incremental concentration of DESs.Compared to the system without DESs,the lag phase of the strain delayed in the order of ChCl:Eg<ChCl:Gly<ChCl:U.When the concentration of DESs is 8%,the survival rate decreased respectively to 45.9%,16.7%and 14.4%in ChCl:U,ChCl:Gly and ChCl:U containing system.This indicated that ChCl:U,delaying the lag phase of A.simplex,is still good biocompability to the strain compared to other DESs.At the same time,the prolonged lag phase,resulting from DESs,has an influence on the reduction of glucose consumption with the order of ChCl:Eg<ChCl:Gly<ChCl:U.This indicated that ChCl:U displayed the highest cell viability among the three DESs tested.To further elucidate the effect of DESs on the A.simplex,scanning electron microscopy(SEM)was used to observe the surface of A.simplex which was treated with ChCl:U containing system.Results indicated that with the increase of concentration of ChCl:U the strain became more rough.Furthermore,the multivariate statistical analysis of the metabolites,performed by GC-MS,revealed the obvious reduction of compounds(succinic acid,glutamine,glacial acetic acid,isoleucine,ornithine,proline,fumaric acid,etc)in cells which were treated with ChCl:U.Furthermore,effects of DESs on cholesterol solubility and cholesterol biotransformation were also studied.Compared to the control,DESs can improve the solubility of the cholesterol to some extent.However,due to the toxicity of DESs on A.simplex,the biotransformation rate is lower.Among these three DESs tested,the highest transformation rate which is only 11.08%lower than the control was obtained when the concentration of ChCl:U(1:2)is 2%,substrate feeding concentration is 2‰.