Submitted to: Phycological Society of America
Publication Type: Abstract Only
Publication Acceptance Date: June 8, 2007
Publication Date: August 9, 2007
Citation: Evens, T.J., Niedz, R.P., Kirkpatrick, G.J. 2007. Temperature and irradiance impacts on the growth, pigmentation and photosystem II quantum yield of Haemotococcus pluvialis (Chlorophyceae). Phycological Society of America.
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 maximizing growth rates 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 micro-mol 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. To this end, a two-dimensional experimental design based on response surface methodology (RSM) was created. This approach allowed us to explore temperature-irradiance interactions within a comprehensive and statistically valid framework. Maximum growth rates were achieved at 27 °C and 260 micro-mol m-2 s-1, while maximum quantum yield of stable charge separation at photosystem II (Fv/Fm) was achieved at 27 °C and 80 micro-mol m-2 s-1. Maximum pigment concentrations correlated closely with maximum Fv/Fm values. As expected, no significant astaxanthin production was found across the design space. Numeric optimization of growth rate and quantum yields produced an optimal combination of 27 °C and 250 micro-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.