title: Flow rate and duty cycle effects in lysis of Chlamydomonas reinhardtii using high-energy pulsed focused ultrasound.
abstract: To consider microalgae lipid biofuel as a viable energy source, it is a necessity to maximize algal cell lysis, lipid harvest, and thus biofuel production versus the energy used to lyse the cells. Previous techniques have been to use energy consumptive ultrasound waves in the 10-40 kHz range in a stationary exposure environment. This study evaluated the potential of using 1.1 MHz ultrasound pulses in a new flow through type chamber on Chlamydomonas reinhardtii as a model organism for cell breakage. The ultrasound was generated using a spherically focused transducer with a focal length of 6.34 cm and an active diameter of 6.36 cm driven by 20 cycle sine-wave tone bursts at varied pulse repetition frequencies. First, variations in flow rate were examined at a constant duty cycle of 3.6%. After assessing flow rates, the duty cycle was varied to further explore the dependence on the tone burst parameters. Cell lysis was assessed by quantifying protein and chlorophyll release into the supernatant as well as by lipid extractability. Appropriate flow rates with higher duty cycles led to statistically significant increases in cell lysis relative to controls and other exposure conditions.
authors.affiliation: Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011.
authors.forename: Grant
authors.initials: G
authors.lastname: Riesberg
authors.affiliation: Department of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Bigelow
authors.affiliation: Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011.
authors.forename: Dan J
authors.initials: DJ
authors.lastname: Stessman
authors.affiliation: Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, Iowa 50011.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Spalding
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University, Ames, Iowa 50011.
authors.forename: Linxing
authors.initials: L
authors.lastname: Yao
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University, Ames, Iowa 50011.
authors.forename: Tong
authors.initials: T
authors.lastname: Wang
authors.affiliation: John Brown University, Siloam Springs, Arkansas 72761.
authors.forename: Jin
authors.initials: J
authors.lastname: Xu
mesh_terms: D020418:Algal Proteins / Q000378:metabolism; D056804:Biofuels; D002458:Cell Fractionation / Q000295:instrumentation / Q000379:methods*; D016825:Chlamydomonas reinhardtii / Q000737:chemistry / Q000528:radiation effects*; D002734:Chlorophyll / Q000378:metabolism; D004867:Equipment Design; D019220:High-Energy Shock Waves; D050356:Lipid Metabolism; D009038:Motion; D013997:Time Factors; D014159:Transducers; D014465:Ultrasonics / Q000295:instrumentation / Q000379:methods*
chemical_list: D020418:Algal Proteins; D056804:Biofuels; D002734:Chlorophyll