Perpustakaan Digital ITB

Polyethylene terephthalate (PET) is one of the most used plastics in various products such as food containers and plastic bags. However, plastic waste derived from these products exhibits an extremely long degradation time and is resistant to natural decomposition. Conventional disposal methods, including incineration and landfilling, have several drawbacks, such as the release of toxic combustion by-products and microplastic contamination of the environment. Therefore, plastic biodegradation technology using engineered PETase enzymes has been developed as an alternative, offering a more environmentally friendly approach without generating harmful by-products. In this study, recombinant Escherichia coli BL21 (DE3) was cultivated in a defined medium to express mutant PETase. High-fructose corn syrup (HFCS) was employed as a cost-effective alternative carbon source to pure glucose in the cultivation medium. The objective of this research was to evaluate the growth performance and mutant PETase production of E. coli BL21 (DE3) transformants in HFCS-supplemented medium induced with IPTG. HFCS was tested at concentrations of 10 g/L, 25 g/L, and 40 g/L. The assessed parameters included maximum cell density (XOD,max), specific growth rate (k), pH, dissolved oxygen (DO), optical density at 600 nm (OD600), residual carbon source concentration, PETase enzymatic activity, and total extracellular protein concentration. Statistical analysis was conducted using ANOVA followed by Tukey's post hoc test at a 95% confidence level. The results demonstrated that E. coli BL21 (DE3) transformants exhibited optimal growth at 10 g/L HFCS, with an XOD,max of 1.862 ± 0.002 (OD600) and a specific growth rate of 0.4922 ± 0.0003 h?¹. SDS-PAGE analysis revealed a protein band at approximately 30.7 kDa, presumed to be the mutant PETase. However, over the 18-hour induction period, no significant changes were observed in PETase activity, which ranged from 38.66 to 76.15 U/mL (p > 0.05), nor in the total extracellular protein concentration, which ranged from 0.103 to 0.139 g/L (p > 0.05). It can be concluded that HFCS holds potential as an alternative carbon source for the cultivation of E. coli BL21 (DE3) transformants. Nonetheless, mutant PETase production was suboptimal under batch cultivation conditions, likely due to limited carbon availability during the induction phase. Further studies are required to evaluate alternative cultivation strategies, such as fed-batch processes, and to optimize carbon source concentration and inducer type to reduce PETase production costs.