Vibration-induced stress priming during seed culture increases microalgal biomass in high shear field-cultivation.

Vibrational wave treatment has been used to increase proliferation of microalgae. When directly applied at large scale, however, turbulence can offset positive effects of vibration on microalgae proliferation. Moreover, severe hydrodynamic shear fields in the bioreactor decrease cell viability that detrimentally influence maximum yieldable biomass. In this study, vibration pretreatment (between 10-30 Hz and 0.15-0.45 G) was used to prime the cells for enhanced biomass. When exposed to 10 Hz at 0.15 G for 72 h and inoculated in baffled flasks of large shear fields (0.292 Pa for the average wall shear force (aveWSF) and 184 s-1 for the average shear strain rate (aveSSR)), microalgae showed 27% increase in biomass as well as 39% increase in corresponding amount of heterologous protein (i.e. GFP-3HA). Our results show that stress primed microalgae with vibrations can lead to improved proliferation that results in increased biomass production at industrial scale bioprocesses.