Purification of fusion peptide biosurfactant using combined chemical extraction and cross-flow microfiltration

• Main Author: Leow, Chee Who
• Format: Thesis
• Language: English
• Published: 2011
• Subjects: TP Chemical technology
• Online Access: http://eprints.utm.my/id/eprint/32782/1/LeowCheeWohMFKA2011.pdf; http://eprints.utm.my/id/eprint/32782/
• Institution: Universiti Teknologi Malaysia

Biosurfactant becomes important nowadays as sustainable bio-derived surfactants emerged to replace the petroleum based surfactant. In this work, the fusion peptide biosurfactant (HSG) was successfully expressed when induced with 1 mM Isopropyl-ß-D-thiogalactopyranoside (IPTG). The combined process of chemical extraction and cross-flow microfiltration was conducted to disrupt the cell membrane and isolate the desired product, HSG. A combination of different concentration of Triton X-100 and Ethylenediaminetetraacetic Acid (EDTA) was investigated to obtain maximized protein extraction from the cells. The efficiency of the chemical extraction was compared with B-PER commercial bacterial extraction kit. Protein estimation was performed using Bicinchoninic Acid (BCA) Protein Assay method and Polyacrylamide Gel Electrophoresis (PAGE) analysis. The results showed that the combination of 1% vv-1 Triton X-100 and 1 mM EDTA released the highest amount of soluble protein and is comparable to the B-PER commercial bacterial extraction kit. The extraction broth is then applied to cross-flow microfiltration process with a 0.2 µm polysulfone hollow fiber membrane. The effect of rotor speed and transmembrane pressure (TMP) for peptide transmission were investigated. The rotor speed for the microfiltration test was varied at 150, 200 and 300 rpm which gave rise to the uncontrolled TMP of 2.5, 2.5 and 4 psig respectively. The highest overall permeate flux achieved at 300 rpm was selected for further investigation at two different TMP of 4 and 5 psig. It was found that the operating conditions at 300 rpm and 5 psig gave 36.33% more protein transmission as compared to operation at 300 rpm and 4 psig. Backpulsing was applied to the microfiltration system to minimize the fouling problem. An overall protein transmission of about 59.6% was achieved with the operating parameter of 300 rpm at constant transmembrane pressure of 5 psig.