We constructed an experimental apparatus that used lasers to provide the probe beams for measuring the transient absorption kinetics of bacterioplankton that contain proteorhodopsin, a microbial protein that binds retinal and is analogous to animal rhodopsin. With this approach we were able to observe photocycles characteristic of functioning retinylidene ion pumps. Using light from lasers instead of broadband sources as transmittance probe beams can be advantageous when examining optically dense, highly scattering samples such as concentrated microbial cultures. Such a laser-based approach may prove useful in shipboard studies for identifying proteorhodopsin in whole cell suspensions concentrated from seawater.
© 2007 Optical Society of America
Original Manuscript: May 7, 2007
Revised Manuscript: September 9, 2007
Manuscript Accepted: August 27, 2007
Published: October 9, 2007
Vol. 2, Iss. 11 Virtual Journal for Biomedical Optics
Russell A. Desiderio, Samuel R. Laney, Ricardo M. Letelier, and Stephen J. Giovannoni, "Using lasers to probe the transient light absorption by proteorhodopsin in marine bacterioplankton," Appl. Opt. 46, 7329-7336 (2007)