Optimization of microbial cell disruption using pressurized CO2 for improving lipid recovery from wet biomass
- 70 Downloads
Microbial cell disruption using pressurized gases (e.g., CO2) is a promising approach to improve the lipid recovery from wet oleaginous microorganisms by eliminating the energy-intensive drying required for conventional methods. In this study, we perform cell disruption of Rhodotorula glutinis using pressurized CH4, N2, and Ar where we find the efficacy of these gases on cell viability is minimal. Since CO2 is found to be the only viable gas for microbial cell disruption among these four gases, we use a combination of Box–Behnken design and response surface methodology (RSM) to find the optimal cell disruption by tuning different parameters such as pressure (P), temperature (T), exposure time (t), and agitation (a). From RSM, we find 6 log reduction of viable cells at optimized conditions, which corresponds to more than 99% cell death at P = 4000 kPa, T = 296.5 K, t = 360 min, and a = 325 rpm. Furthermore, from the scanning electron microscope (SEM), we find a complete morphological change in the cell structure when treated with pressurized CO2 compared to the untreated cells. Finally, we find that up to 85% of total lipid can be recovered using optimized pressurized CO2 from wet biomass compared to the untreated wet cells where up to 73% lipid can be recovered.
KeywordsCell disruption Biofuels Pressurized gas Design of experiment Optimization
The author is thankful to the Dave C. Swalm School of Chemical Engineering and Bagley College of Engineering, Mississippi State University for the financial support to complete the research. The author is also grateful to Mrs. Amanda Lawrence for her help in sample preparation and running scanning electron microscope. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
- 5.Xu J, Zhao X, Wang W et al (2012) Microbial conversion of biodiesel byproduct glycerol to triacylglycerols by oleaginous yeast Rhodosporidium toruloides and the individual effect of some impurities on lipid production. Biochem Eng J 65:30–36. https://doi.org/10.1016/J.BEJ.2012.04.003 CrossRefGoogle Scholar
- 7.Zhao X, Peng F, Du W et al (2012) Effects of some inhibitors on the growth and lipid accumulation of oleaginous yeast Rhodosporidium toruloides and preparation of biodiesel by enzymatic transesterification of the lipid. Bioprocess Biosyst Eng 35:993–1004. https://doi.org/10.1007/s00449-012-0684-6 CrossRefGoogle Scholar
- 15.Zheng H, Yin J, Gao Z et al (2011) Disruption of Chlorella vulgaris cells for the release of biodiesel-producing lipids: a comparison of grinding, ultrasonication, bead milling, enzymatic lysis, and microwaves. Appl Biochem Biotechnol 164:1215–1224. https://doi.org/10.1007/s12010-011-9207-1 CrossRefGoogle Scholar
- 18.Hobbie JE, Daley RJ, Jasper S (1977) Use of nuclepore filters for counting bacteria by fluorescence microscopy. Appl Environ Microbiol 33:1225–1228Google Scholar
- 30.Hong S-I, Pyun Y-R (1999) Inactivation kinetics of Lactobacillus plantarum by high pressure carbon dioxide. J Food Sci 64:728–733. https://doi.org/10.1111/j.1365-2621.1999.tb15120.x CrossRefGoogle Scholar
- 36.Box GEP, Wilson KB (1992) On the experimental attainment of optimum conditions. Springer, New York, pp 270–310Google Scholar
- 37.Gunst RF (1996) Response surface methodology: process and product optimization using designed experiments. Taylor and Francis Group, LondonGoogle Scholar
- 45.Debs-Louka E, Louka N, Abraham G et al (1999) Effect of compressed carbon dioxide on microbial cell viability. Appl Environ Microbiol 65:626–631Google Scholar
- 52.Tommasi E, Cravotto G, Galletti P et al (2017) Enhanced and selective lipid extraction from the microalga P. tricornutum by dimethyl carbonate and supercritical CO2 using deep eutectic solvents and microwaves as pretreatment. ACS Sustain Chem Eng 5:8316–8322. https://doi.org/10.1021/acssuschemeng.7b02074 CrossRefGoogle Scholar
- 55.Meullemiestre A, Breil C, Abert-Vian M, Chemat F (2016) Microwave, ultrasound, thermal treatments, and bead milling as intensification techniques for extraction of lipids from oleaginous Yarrowia lipolytica yeast for a biojetfuel application. Bioresour Technol 211:190–199. https://doi.org/10.1016/j.biortech.2016.03.040 CrossRefGoogle Scholar