Lipase produced by Aspergillus is widely known and used in many industrial sectors. Three lipolytic filamentous fungi had been isolated from Kendari (Southeast Sulawesi, Indonesia) landfill soil in previous study and identified as Aspergillus niger KE1, Aspergillus terreus KC1, and Aspergillus fumigatus KE6. However, the optimization of these isolate has not been reported. In this study, statistical optimization is selected because of more effective, efficient, economical, robust in giving the results and the possibility of analysing the interaction effects among factors. Three lipolytic isolates were screened in initial medium to obtain the highest lipolytic isolate and it was used in medium optimization process. Optimization was done using the series experimental design of Taguchi and RSM. Optimization was sucessfully obtain the optimum medium with the reduction of medium component from previously medium reported. Aspergillus niger KE1 is the selected isolate with the highest lipase productivity after 72 h in initial medium. The significant factors affected lipase production are peptone, olive oil, glucose and MgSO4.7H2O. The model equation obtained is Y = 1043 – 228 A + 300 B – 19803 C + 99 A*A + 5720 B*B + 292855 C*C – 979 A*B + 6563 A*C – 56338 B*C. This model predicts the lipase productivity succesfully with R2 of 96.9%. The optimized medium composes of peptone 2%, olive oil 0.1%, glucose 0.5% and MgSO4.7H2O 0.075%. Using the medium, the lipase productivity increases 4.7-folds compared with before optimization. Our results suggest that Aspergillus niger KE1 is a potential lipase source which catalyse the esterification reaction. Further research is needed to purify and characterize the lipase enzyme of this isolate.
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