Sustainable,
high-yielding outdoor mass cultures of Chaetoceros muelleri var. subsalsum
and Isochrysis galbana in vertical plate reactors
C.W. Zhang, A. Richmond-2003
Marine
Biotechnology, 5(3): 302-310 (from
ISI Current Contents)
Abstract:
Continuous cultures of Chaetoceros muelleri and Isochrysis galbana were
grown outdoors in flat plate-glass reactors in which light-path length (LPL)
varied from 5 to 30 cm. High daily productivity (13 to 16 g cell mass per
square meter of irradiated reactor surface) for long periods of time was
obtained in reactors in which the optical path as well as cell density were
optimized. Twenty centimeters was the optimal LPL, yielding the highest
areal productivity of cell mass (g m(-2) d(-1)), eicosapentaenoic acid, and
docosahexaenoic acid, which was identical with that previously found for
polysaccharide production of Porphyridium and not far from the optimal LPL
affecting maximal productivity in Nannochloropsis species. Relating the
energy impinging on a given reactor surface area to the appropriate number
of cells showed that the most efficient light dose per cell, obtained with
the 20-cm LPL reactor, was approximately 2.5 times lower than the light dose
available per cell in the 5-cm LPL reactor, in which a significant decline
in areal cell density accompanied the lowest areal output of cell mass. The
most effective harvesting regimen was in the range of 10% to 15% of culture
volume harvested daily and replaced with fresh growth medium, resulting in a
sustainable culture density of 24 x 106 and 28 x 106 cells/ml of C. muelleri
and L galbana, respectively.
(Ben Gurion Univ. Negev., Jacob Blaustein Inst. Desert Res. Microalgal
Biotechnol. Lab. Albert Katz Dept. Dryland Biotechnol.; IL-84990 Sede Boqer,
Israel, e-mail of A. Richmond: amosr@bgumail.bgu.ac.il)