Enzymatic antioxidant response to low-temperature acclimation in the cyanobacterium Arthrospira platensis

Changes in antioxidant enzyme activities in response to low-temperature-induced photoinhibition were investigated in the two strains of the cyanobacterium Arthrospira platensis, Kenya and M2. When transferred to 15°C from 33°C, cells exhibited an immediate cessation of growth followed by a new acclimated growth rate. Although both strains had similar growth rates at 33°C, once transferred to a lower temperature environment, Kenya had a faster growth rate than M2. There were variations in the antioxidant enzyme activities of both strains during 15°C acclimation. The activity of superoxide dismutase from Kenya was higher than that from M2 and increased remarkably with acclimation time. Catalase activity of both strains increased at first but decreased later in the acclimation process. Ascorbate-dependent peroxidase activity of the Kenya strain declined when transferred to the low-temperature environment while peroxidase activity of M2 decreased in the beginning and then increased with time. The dehydroascorbate reductase activity of both strains was variable during the acclimation period while the glutathione reductase activity was not modified immediately. Our finding may support that the faster growth rate of the Kenya strain at lower temperatures as compared with the M2 strain might be explained by the higher antioxidant enzyme activities of Kenya at lower temperatures and through its ability to apply a more efficient regulatory strategy of enzymatic antioxidant response to low-temperature-induced photoinhibition.