Spectrometric Characteristics and Underlying Mechanisms of Protective Effects of Selenium on Spirulina Platensis against Oxidative Stress
ABSTRACT To investigate the possibility and the underlying mechanisms of sodium selenite as antagonist for oxidative stress, the authors examined the effects of pretreatment with selenium on the growth, morphology, spectrometric characteristics and content of reactive oxygen species (ROS) in Spirulina platensis (S. platensis) exposed to H2O2 stress for 24 h in the present study. The results showed that H2O2 induced obvious inhibition of growth and serious morphological damage. The intensity of absorbance peak at 440 nm increased, whereas the peaks at 620 and 680 nm decreased after exposed to H2O2. The emission and excitation spectrum of S. platensis decreased dramatically after H2O2 treatment, and the emission peak from phycocyanin exhibited blue-shift from 660 to 650 nm. The results of FTIR analysis showed that the positions of transmission peaks had no shift, but the relative intensity of characteristic bands from protein and polypeptides including amide I and amide II decreased. Furthermore, the intracellular ROS generation in S. platensis increased significantly in response to H2O2 treatment. In contrast, pretreatments of the cells with selenium for 24 h significantly prevented the H2O2-induced oxidative damages in a dose-dependent manner. Taken together, our results indicate that pretreatments with selenium could prevent ROS overproduction in S. platensis and improve its antioxidant ability. Moreover, selenium could also reduce the effects of free radicals on energy harvest and energy transfer in S. platensis that play vital roles in its photosynthesis.
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ABSTRACT: Using 3-D fluorescence spectroscopy (EEMs), infrared spectroscopy (FTIR) and transmission electron microscope (TEM), the composition and characteristics of dissolved organic matter (DOM) from degradation products and inhibition mechanism of Streptomyces sp. HJC-D1 on Microcystis aeruginosa were studied. The results indicated that the growth of M. aeruginosa could be effectively inhibited by the fermentation broth of HJC-D1 and the removal efficiency was 72.6% +/- 5.5% with an addition dosage of 5% (see system for text). The main fluorescent material in DOM was humic-like acid, and the molecular weight of degradation products was around 1 000 Da. The cell structure of M. aeruginosa was damaged during the biodegradation process. With the results of TEM, the antialgal mechanism was speculated as following: M. aeruginosa cell walls are destroyed by antialgal bacterium, and organelles are released which resulted in the death of algae cell finally.Guang pu xue yu guang pu fen xi = Guang pu 01/2013; 33(1):167-71. DOI:10.3964/j.issn.1000-0593(2013)01-0167-05 · 0.27 Impact Factor