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. Cry-oprote-ctiye-tre-atme-nt, Two different cryoprotective additives were prepared in purified water (Milli Q) Tbe first is a simpte 20 % s.rcrose solution; the second is a mixrure of pollvinylpynolidone soludon (PVP, sucrose ssd 6srhenst

A. Lo, %. Wv, and . Pvp, 000 (SIGMA, 9003-398) was first buffered wirh 0.01 M HEPES rsing a back tiuadon rc a pH 7.0 wiù KOH; sucrose (MERCK,7653) ard merhenol (> 98') soludons were then added to give a final concentration of 20 %(wlv) sucrose and 6

T. Freezîng, Cells were cooled in a minicooler (Nicool LM l0) ar two differenr rares: a) a slow rete (=l.soC i nrin) undl -3OoC, followed by a fast freezing (=10.5 'C / min) unril -80.c b) a fast rate (=10, p.80

. Iliability-ossots, CelI viability, after a freezing-thawing eycle, was assaesed by rneasuring algal growth on either liquid or solid medium in triplicates. Liquid (oligo-L.C.) medium was .rsàd and inhibition of growth was estimated according to ISO 8692 (13), using cell counting (Coulter counter ZVf) aft'er 48 and 96 houns of incubation. The agar plate -elhod (8)

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