PEMODELAN KINETIKA DAN OPTIMASI PERTUMBUHAN SERTA AKUMULASI LIPID DALAM KULTUR SPIROGYRA SP. DENGAN PENAMBAHAN STRES CU2+ MENGGUNAKAN PENDEKATAN RESPONSE SURFACE METHODOLOGY (RSM)

• Main Author: Kambani Panggabean, Josua
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/73255
• Institution: Institut Teknologi Bandung

<p align="justify">Spirogyra sp. is one of the potential green macroalgae that can be utilized as a valuable source of high-worth bioproducts. The lipid fraction of Spirogyra sp., which contains Polyunsaturated Fatty Acid (PUFA) and Saturated Fatty Acid (SFA), has the potential to be used as raw material for pharmaceutical and nutraceutical products. The lipid content in Spirogyra sp. is relatively low, therefore, it needs to be increased through modification of the cultivation medium components, such as the addition of metal stress. The influence of copper metal addition on the growth and lipid accumulation of Spirogyra sp. is explored to obtain optimal cultivation conditions and lipid productivity. The design of determination and analysis of optimal conditions is done using Response Surface Methodology (RSM) by applying Cu2+ at concentrations of 0,29, 0,49, 0,99, 1,9, and 1,7 mg/L in the algal culture. Biomass and lipid data are analyzed using kinetic modeling (logistic and Luedeking-Piret). The Bligh and Dyer method is used to extract Spirogyra sp. lipid. Lipid profile analysis is performed using GC-MS (Gas-Chromatography Mass-Spectrophotometry). The results of the study show that the addition of Cu2+ from a concentration of 0,29 to 1,7 mg/L can decrease biomass growth but increase lipid accumulation. Testing from the RSM design shows an optimal lipid content of 106,61 mg/g dry weight (dw) with a biomass of 0,52 g under the optimized treatment of Cu2+ at 0,78 mg/L and a cultivation duration of 9,54 days. Kinetic modeling with the logistic equation shows that the best biomass growth occurs at a concentration of 1,49 mg/L with ?m and Xm values of 0.101 day-1 and 429,6 mg, respectively. R2 values > 0.8 indicate that the model can represent the research data well. The Luedeking-Piret modeling reveals a partial association (mix-growth associated) relationship between lipid accumulation and biomass growth. GC-MS analysis detected the presence of SFA in the form of caproic acid (9,16 mg/gdw), valeric acid (7.10 mg/gdw), and butyric acid (9.21 mg/gdw).