The cultures of Platymonas subcordiformis and Isochrysis zhangjiangensis which had preserved for long time was irradiated by Nd:YAG laser(1.06 μm,5 W)with different dose.Then,the effects of laser on algae growth,physiological and biochemical characteristic were investigated.The feasibility to utilize laser in the activation and rejuvenation of microalgae were discussed.The results showed that the optimal dosage to rejuvenate I.zhangjiangensis is 60 s,which the growth rate,cell biomass,the contents of chlorophyll,polysaccharides and protein increased by 27.59%-43.44% after Nd:YAG radiation.For P.subcordiformis,the better results of rejuvenation by Nd:YAG laser was got when irradiation dose at both 60 s and 90 s.It is favourable to the growth of P.subcordiformis by using lower irradiation dose of Nd:YAG laser,which the growth rate and the contents of chlorophyll increased by 12.5% and 17.5% respectively.By contrast,the higher irradiation dose was favourable to the increase of other biomass of P.subcordiformis,which the contents of carotenoids,protein and polysaccharides increased by 87.7%,15.5% and 36.8% respectively.The results of Laser Scanning Confocal Microscope(LSCM)showed that the fluorescence spectra of the irradiated group is similar to control group with the maximum peak located at 682 nm which can be attributed to photosystemⅡ.While the irradiated group which the growth had be promoted has a higher intensity at 682 nm than control group.In this paper,the possible mechanism of activation and rejuvenation effects on microalgae induced by laser irradiation was also discussed.These results can offer a theoretical foundation to utilize laser in breeding of microalgae species for aquiculture.
