Enhancement in Chlorella

Emerson and coworkers (4, 5, 8) discovered that low quantum yields of photosynthesis observed at long wavelength (near 700 m/A) could be increased by supplemental or background light of shorter wavelength. The Emerson enhancement effect has been studied further in the belief that it should provide a key to the role of the various pigments. Considerable attention has been devoted to the reality and generality of the effect and to spectra of the shortwave component of enhancement. All such spectra support the view that the short-wave component includes one or more of the accessory pigments characteristic of the plant used: chlorophyll b, chlorophyll c, phycocyanin, phycoerythrin, fucoxanthol, and the chlorophyll a-673 (2, 8, 9, 14). The present work is concerned with the nature of the long-wave component of enhancement and the quantitative characteristics of enhancement in Chlorella. To this end we have improved upon the polarographic electrode used (24) and have introduced two monochromators in order to obtain reasonable resolution in each of two light beams.