Tolerance of
three marine microalgae to cryoprotectants dimethyl sulfoxide, methanol and
glycerol
I. Joseph, A. Panigrahi,
P.K. Chandra-2000
Indian Journal of Marine Sciences, 29 (3) : 243-247
(from Current Contents)
Abstract :
Studies on tolerance limit of cryoprotectants is of
much importance in determining the viability of cells after freezing them at
below normal temperatures. Tetraselmis gracilis showed survival on exposure
to 5 to 30% (v/v) DMSO, 5 to 25% methanol and 5 to 40% glycerol for periods
of up to 2 h. DMSO and methanol were lethal at higher concentrations
(>10%) for Chlorella marina and Chaetoceros calcitrans even on exposure
for 15 min. At 25%, DMSO was so much lethal that the cells of C. calcitrans
and C. marina were dead even after 60 sec. At 20%, all cells were dead
within 60 min. Safer concentrations for DMSO were at 5% and lower. Methanol
incubations significantly reduced cell viability above 25% (60 sec) for T.
gracilis, 15% (up to 20 min) for C. calcitrans and 20% (up to 60 min) for C.
marina. All the three algae could tolerate glycerol even up to 30% (60 min).
The survival was highest at 10% concentration of glycerol for 120 min. Based
on cell recovery rate after 24 h post thaw and growth rate determination,
DMSO at 5% or 10% glycerol are the best treatments for cryopreservation.
Glycerol was found to be better than DMSO in all the three cases. Post thaw
viability in 5% methanol was almost negligent fur all the three strains.
(CIBA, NRC, Cochin 682505, Kerala, India)