周囲流体のShear thinning性による細菌の遊泳運動の影響

抄録

We investigate the swimming behavior in shear thinning fluid using the monotrichous bacterium Vibrio alginolyticus YM4 and the peritrichous bacterium Salmonella enterica serovar Typhimurium SJW1103. In Polyvinylpyrrolidone solution (PVP), which is a Newtonian fluid, the swimming speed of both YM4 and SJW1103 decreases as the viscosity increases. In MC (Methylcellulose) 400 and MC4000, which are shear thinning fluids, the swimming speed does not decrease so much. In MC solution, the swimming speed of SJW1103 does not decrease as the increasing viscosity in MC400 and MC4000. We estimate the shear rate around the cell body and the flagellum of swimming bacterial cells. By applying the estimated shear rate to the measurement of the viscosity of the test fluids, it is found that in the shear thinning fluid, the viscosity around the flagella, where the shear rate is high, is several times lower than that around the bacterial body.