Study On The Permeabilization And Immobilization Of Microbial Cells Producing Lipase

The methods and conditions of permeabilization and immobilization on Trichosporon fermentans cells producing lipase were studied. The immobilized whole cells were used for the transesterifiation reaction of soybean oil. The utilization performance of permeabilized immobilized cells was improved, as well as the preservation and utilization stability of various immobilized cells was tested. The conclusions were as follows.(1) Cells was induced to produce lipase by treating the cells with soybean oil at the beginning of fermentation.(2) The permeability of Trichosporon fermentans cells was improved by treating cells with permeabilization agents and the intracellular lipase activity was enhanced. The permeab-ilizing performance was better when cells were treated in2%methylbenzene for40min,2%chloroform for10min and25%acetone for40min. The permeabilized cells could reach the maximum intracellular lipase activity23.4U/g cell which was prepared with2%chloroform for10min and then dried in air at room temperature, furthermore kept91%initial lipase activity within preservation period of30days.(3) Trichosporon fermentans cells were adsorbed by active carbon of40mesh and silica gel G and macroporous resin DM-130separately. Carbon active was suitable immobilization carrier. The immobilized cells could reach the highest lipase activity100.88U/g cell, which were adsorbed with1.0g active carbon for48h by100mL submerged fermentation in250mL shaking flask at30℃,160rpm.(4) Lipase activity of immobilized cells was high, which were permeabilized and then were cross-linked with5%glutaral for10min. Lipase activity was obviously enhanced by permeabilizing and then treating the cells for120min in O.lmol/L glucose solution. Compared with untreated immobilized cells, their lipase activity increased by67%and1.7times.(5) Lipase activity of immobilized cells kept stable at4℃within30days preservation period, which were treated with permeabilization agent and glutaral and glucose solution separately. When permeabilized immobilized cells with glutaral treating were used for the transesterification reaction of soybean oil in sequence for10batches, the esterification rate maintained50%above.(6) The cell adsorption quantity and lipase activity of immobilized cells could reach92%and91%of initial carrier when cells were immobilized on regenerated active carbon by acid soaking.