(757d) Solubility of Carbon Dioxide in Sugar Broth, Rhodotorula Glutinis, and Spent Cell: A Preliminary Study of Cell Disruption Using High Pressure Carbon Dioxide

The lysing of cells improves the lipid extraction from oleaginous microorganisms and reduces the cost of biodiesel production. This study investigated the lysing of Rhodotorula glutins under high pressure carbon dioxide. The process involves solubilization of gas by applying pressure to the cell and then, a sudden release of pressure. The gas expands because of sudden pressure release and mechanically ruptures cell walls like a popped balloon. Hence, the solubility of a gas in liquid was also investigated in this study. The solubility of carbon dioxide in sugar broth media, grown R. glutins, and spent media (obtained by centrifuging the R. glutins) were measured. A novel experimental technique was developed to measure the solubility of gas in liquid. The molar volume of the designated gas (CO₂) was estimated using Peng Robinson equation of state (PR EOS). The solubility of carbon dioxide was measured at three temperatures of (288.15, 291.15, and 295. 15 K) and four initial pressures of (1400, 2100, 2800, and 3100 kPa). The results of solubility of carbon dioxide in water was used to validate the experimental procedure. The solubility CO₂ in sugar broth media, and in spent media were found to be the same. Due to the presence of different salts in the media, the solubility was found to be lower than that of water.The solubility of carbon dioxide in R. glutinis was found higher than that of sugar broth and spent media due to the presence of lipids (triglycerides) in the cell. Both the carbon dioxide and lipid are nonpolar in nature; as a result, the solubility in R. glutinis was found to be higher. Cell disruption was conducted at two distinct pressures of (2000 and 3500 kPa). Scanning electron microscopy (SEM) was used to visualize the cell structure before and after the disruption. A significant change in the cell structure was observed before and after the disruption.  The disruption procedure was found to be different at 3500 kPa because more cells were disrupted at higher pressure, which indicates high pressure facilitate the disruption procedure.