The Research Of Fermentation Conditions On Penicillin G Acylase Producing Bacteria

Penicillin G acylase is an important industrial enzymes.In this study, casein hydrolysate was used as nitrogen source. The medium composition and fermenting conditions on producing penicillin G acylase of Bacillus megaterium,Bacillus cereus,Bacillus subtilis were studied. The UV mutagenesis was studied on strains with the ability of the enzyme production. A mixed flora was build and the fermentation conditions were researched. The results are as follows:(1) Casamino as the nitrogen source,the Penicillin G acylase activity of bacillus megaterium is the best,when medium composed of Glucose4.28g/L,Casamino10g/L,pHenylacetic acid18.43g/L,MgCl2·6H2O0.5g/L, FeCl3·6H2O0.002g/L, under this condition of liquid volume19.3%in eriochrome flask, inoculation5.6%, fermentation at28℃and48h.(2) Casamino as the nitrogen source,the Penicillin G acylase activity of bacillus cereus the best,when medium composed of beef extract6.78g/L,Casamino12g/L,Sodiumcitrate5.72g/L,K2HPO44.24g/L,Glycerin50g,Nacl4g/L,0.1%FeSO40.5ml,20%MgSO4lml,under this condition of liquid volume16%in eriochrome flask,inoculation9%,fermentation at28℃and74.8h.(3) Casamino as the nitrogen source,the Penicillin G acylase activity of bacillus subtilis the best,when medium composed of Glucose5.91g/L,Casamino12g/L,Starch5.89g/L,Yeast powder20g/L,Nacl3g/L,under this condition of liquid volume16%in eriochrome flask, inoculation10%, fermentation at36.2℃and36h.(4)Mutant T1-1and T3-1is obtained by UV mutagenesis of Bacillus cereus21090,the activity of PGA Produced by them were331.73U/L,351.87U/L,were higher than the enzyme activity of Bacillus cereus (21090).(5)Mixed flora are build of bacillus megaterium is:bacillus cereus:bacillus subtilis=1.5:2:1.1, under this condition of liquid volume24%in eriochrome flask, inoculation10%, fermentation at29.8℃and72h,medium composed of Glucose,7g/L,casamino16.17g/L,beef extract6.83g/L,magnesium chloride0.4g/L,starch6g/L,yeast extract20g/L,sodium citrate6g/L,dipotassium hydrogen phosphate4g/L.compared with bacillus megateriumis,Mutant T3-1and bacillus subtilis,the activity of PGA improved54.79%,2.08%,44.53%.