Submitted to: Journal of Applied Phycology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2007
Publication Date: 8/1/2008
Citation: Evens, T.J., Niedz, R.P., Kirkpatrick, G.J. 2008. Temperature and Irradiance Impacts on the Growth, Pigmentation and Photosystem II Quantum Yields of Haematococcus pluvialis (Chlorophyceae). Journal of Applied Phycology. 20:411-422. Interpretive Summary: The purpose of this study was to determine how temperature and light affect the growth rate, photosynthesis and pigmentation of the microalga Haematococcus pluvialis. This alga is important for two reasons, 1) it is found in all temperate and tropical areas of the world, and can play an important role in algal community dynamics, and 2) H. pluvialis produces the pigment astaxanthin which is very important as an additive to animal feeds and human nutriceuticals. There have been many studies that have attempted to define the optimal temperature and irradiance for growth of Haematococcus, but the results have been inconsistent. "Ideal" temperature-irradiance combinations for growing Haematococcus have ranged from 14-28 °C and 30-200 umol m-2 s-1. This experiments reported here utilized a complex, geometric approach to experimental design that allowed us to examine growth of Haematococcus across the entire range of temperature and light that has been reported as optimal, and to examine the interaction/interplay between these two important factors. Results indicate that the optimal temperature-light combination for Haematococcus is 27 °C and 250 umol m-2 s-1 light. No previous study has identified the optimal region as identified by this study.
Technical Abstract: The microalga Haematococcus pluvialis Flotow has been the subject of a number of studies concerned with maximizing astaxanthin production for use in animal feeds and for human consumption. Several of these studies have specifically attempted to ascertain the optimal temperature and irradiance combination for growth of H. pluvialis, but there has been a great deal of disagreement between laboratories. “Ideal” levels of temperature and irradiance have been reported to range from 14 to 28 °C and 30 to 200 umol m-2 s-1. The objective of the present study was to simultaneously explore temperature and irradiance effects across an experimental region that encompassed all of the reported “optimal” combinations of these factors. Maximum growth rates were achieved at 27 °C and 260 umol m-2 s-1, while maximum quantum yield of fluorescence was achieved at 27 °C and 80 umol m-2 s-1. Maximum astaxanthin production during vegetative growth was achieved at XX °C and XX •mol m-2 s-1. Numeric optimization of growth rate and quantum yields produced an optimal combination of 27 °C and 250 •mol m-2 s-1. Polynomial models of the various response surfaces were validated with multiple points and were found to be very useful for predicting several H. pluvialis responses across the entire two-dimensional design space.