Measurement of individual cell strength of Botryococcus braunii in cell culture
Botryococcus braunii is a microalga considered for biofuel production and may require physical disruption of cells/colonies for efficient hydrocarbon extraction. In this study, the strength of individual cells of B. braunii was measured using a nanoindenter. From the load and cell size, the pressure for bursting the cell was calculated to be 56.9 MPa. This value is 2.3–10 times those of Saccharomyces cerevisiae and Chlorella vulgaris found in another research, because B. braunii has two types of cell walls with different thicknesses. The energy required to disrupt 1 g of dry B. braunii cells, estimated by load-displacement curves, is 3.19 J g−1 which is 0.19–1.2 times higher than those of S. cerevisiae and C. vulgaris. When using a high-pressure homogenizer for disrupting B. braunii cells, the cell disruption degree increased with the treatment pressure at above 30 MPa, and 70% of cells were disrupted at 80 MPa.
KeywordsMicroalgae Botryococcus braunii Cell strength Cell disruption Nanoindentation
The authors would like to thank Prof. H. Inomata and Dr. M. Ota, Department of Chemical Engineering, Tohoku University, for lending us the UV-Vis spectrophotometer.
This work was supported by the Next-Generation Energies for Tohoku Recovery (NET) project of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan. The samples of B. braunii were provided by the University of Tsukuba. The cell compression test using nanoindentation was supported by the Kyoto University Nano Technology Hub in “Nanotechnology Platform Project” sponsored by MEXT, Japan.
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