Mechanism of low temperature Isochrysis galbana Parke 8701 tolerance of Isochrysis galbana Parke 8701

This paper reports several physiological and biochemical changes related to active oxygen injure and scavenging effect in a low temperature resistant strain Isochrysis galbana Parke 8701 under low temperature stress and investigates its low temperature tolerant mechanism in comparison with a low temperature sensitive strain I. galbana Parke 3011. The experimental results showed that : ⑴the activity of superoxide dismutase (SOD) in I. galbana Parke 8701 decreased slightly when cultured at low temperature ( 8 ℃) for a week , but still kept extremely high enzymatic activity , so it could scavenge the extra active oxygen rapidly under low temperature stress and keep a membrane lipid peroxidation in relatively lower level as well as a relatively low electrolytic leakage; ⑵the membrane lipid peroxidation level and electrolytic leakage in I. galbana Parke 3011 were significantly higher than in I. galbana Parke 8701 when stressed under low temperature for a week. This was due to the relatively low SOD activity in the former and its activity rapidly declined; ⑶in comparison with SOD , peroxidase (POD) did not play an important role in relieving the low temperature injury and raising the capacity of low temperature tolerance in these two strains of I. galbana Parke.