Limitations on microalgal growth at very low photon fluence rates: the role of energy slippage.

The lower limits of photosynthetically useable radiation at which growth and photosynthesis can occur establish the lower boundaries for the extent of photolithotrophy in the biosphere. Photolithotrophic growth denotes the capacity to grow with photons as the sole energy input. Slippage in terms of photosynthetic energy conversion implies a less than theoretical stoichiometry of energy-transduction process(es) such as the dissipation of intermediates of O(2) evolution and of ATP synthesis (H(+)/e(-) and H(+)/ATP ratios).