Effect Of High Temperature And Solar UV Radiation On Growth And Physiology Of Spirulina And Arthrospira Platensis

Nowadays, high temperature and intensive UVR are primary environmental problem all organisms confronted. In this paper, the effect of high temperature and solar UVR on the growth condition and physiological change of Spirulina and Arthrospira platensis were studied. The main research contents and results are as follows:Arthrospira platensis OUQDS6 and its linear filaments mutant strain OUQDS6L (S6L)were cultured in high temperature environment from 38℃to 48℃. The effect of high temperature on the physiological changes were measured. The results are that, with increasing the high-temperature stress, their specific growth rate and chla contents were decreased gradually, Car contents were increased under lower stress and then decreased with higher temperature stress. PC and APC contents decreased significantly; The sensitivity of the 4 kind of photosynthesis pigment to high temperature stress are different, from high to low was PC, APC, Chla and Car. MDA accumulated during all stress period, SOD, CAT activity were increased under low stress and then decreased significantly with higher temperature stress. Pro had no significant accumulation during all stress periods. Both of S6H and S6L have strong ability to adapt high temperature environment, although wild type A.platensis are more adaptable to high temperature than the linear filaments mutant strain .To study the impact of solar UV radiation (UVR) (280 to 400 nm) on the filamentous cyanobacterium Spirulina and Arthrospira platensis, the Colony and individual growth condition changes were examined using an Spirulina and four Arthrospira platensis strains while they were cultured with three solar radiation treatments: PAB (photo synthetically active radiation [PAR] plus UVR; 280 to 700 nm), PA (PAR plus UV-A;320 to 700 nm), and P (PAR only; 400 to 700 nm). The results are that: Strains with long filaments came together in short time when exposed to full solar radiation, Growth rate of long filament Strains was less influenced than short filament strains suggests that convergence was an effective mechanism to protecting long filament against UVR. Filament sinkage was observed obviously in several days for short filament when exposed to UVR, filament sinkage is probably play an important role for short filaments to avoid UV radiation .Filament breakage also occurred in the cultures exposed to UVR. Helix with long filament strain OUQDS6H increased the helix pitch and became loosely arranged under UVR, The spiral filaments broke and elongated allowed convergent body a balance between obtain enough visible light and protection against solar UVR. Helix with short filament strain FACHB438 decreased the helix pitch and become compressed in the presence of UVB, compact structure, which result in self-shading is probably an effective protective mechanism. We also found helix filaments in linear filament strain FACHB793 under solar UVR, but the helix character cannot pass down steadily. Chla contents decreased in all strains when subject to UVR, The low levels of UV-absorbing compounds found in Spirulina and Arthrospira platensis both in control and experimental group indicate that MAAs might have played a small role in protection against UVR-induced damage.