Induced deflagellation of Isochrysis microalgae in a near-infrared optical trap

Veneranda G. Garces, Oscar Salazar-Oropeza, Beatriz Cordero-Esquivel, and Kevin A. O’Donnell

We report on the observation of an in situ deflagellation of an Isochrysis microalgae cell with a near-infrared laser beam. In particular, a cell is caught in an optical trap and is later observed to lose its flagella; the time required is termed the deflagellation time. The dependence of the average deflagellation time on cell growth rate phase is studied. For cells in the initial growth rate phase, this time (∼26  s) is considerably longer than observed in the stationary phase (∼16  s). The cellular transmittance is observed to fall with age, suggesting that the increased optical absorption and scattering may be related to the more rapid deflagellation. The dependence of deflagellation time on laser trapping power is consistent with a single-photon process. No significant difference was found in the deflagellation time for cells kept either in the dark or under light. The deflagellated cells were viable after showing the reappearance of red chlorophyll autofluorescence and cell division. Our observations reported here provide insight into the photostimulus produced by near-infrared light in Isochrysis and other living organisms.

DOI