Polysaccharides from Spirulina platensis (PSP): promising biostimulants for the green synthesis of silver nanoparticles and their potential application in the treatment of cancer tumors.

Photosynthetic cyanobacterial components are gaining great economic importance as prospective low-cost biostimulants for the green synthesis of metal nanoparticles with valuable medical and industrial applications. The current study comprises the biological synthesis of silver nanoparticles (Ag-NPs) using soluble polysaccharides isolated from Spirulina platensis (PSP) as reducing and capping agents. FTIR spectra showed major functional groups of PSP and biogenic silver nanoparticles including O-H, C-H (CH2), C-H (CH3), C=O, amide, and COO- groups. The UV/Vis spectroscopy scan analyses of the extracted PSP showed absorption spectra in the range of 200-400 nm, whereas the biogenic Ag-NPs showed a maximum spectrum at 285 nm. Transmission electron microscopy (TEM) analysis of the synthesized Ag-NPs showed spherical nanoparticles with mean size between 12 and 15.3 nm. The extracted PSP and Ag-NPs exhibited effective cytotoxic activity against Hep-G2 (human hepatocellular carcinoma). The IC50 for PSP and Ag-NPs were 65.4 and 24.5 µg/mL, respectively. Moreover, cell apoptosis assays for PSP and Ag-NPs against the growth of Hep-G2 cells revealed superior growth inhibitory effects of the green synthesized Ag-NPs that encouraged tracing the apoptotic signalling pathway. In conclusion, the current study demonstrated an unprecedented approach for the green synthesis of silver nanoparticles (NPs), using the polysaccharide of Spirulina platensis as reducing and capping agents, with superior anticancer activity against a hepatocellular carcinoma cell line.

Potential use of beneficial fungal microorganisms and C-phycocyanin extract for enhancing seed germination, seedling growth and biochemical traits of Solanum lycopersicum L.

BACKGROUND: Biopriming as a new technique of seed treatment involves the application of beneficial microorganisms on the seed surface to stimulate seed germination, plant growth, and protect the seed from soil and seed-borne pathogens. The present investigation was carried out on seed germination, seedling vigor and biochemical traits of one of the most important vegetable crops (Tomato, Solanum lycopersicum L.). The treatments comprised viz. T1: Non primed seeds (Control), T2: Hydropriming, T3: Biopriming with C-phycocyanin (C-PC) (Spirulina platensis extract), T4: Biopriming with Trichoderma asperellum, T5: Biopriming with T. viride, T6: Biopriming with Beauveria bassiana. RESULTS: Extraction and purification of C-phycocyanin (C-PC) from the dry S. platensis powder using various methods was performed. The purity after dialyses was 0.49 and its ultimate purity (A620/A280) after ion-exchange chromatography was 4.64. The results on tomato seedlings revealed that the maximum germination percentage (100%), germination index (15.46 and 15.12), seedling length (10.67 cm), seedling dry weight (1.73 and 1.97 mg) and seedling length vigor index (1066.7) were recorded for tomato biopriming with T. viride, and B. bassiana (T5 and T6). Moreover, the quantitative estimation of total carbohydrates and total free amino acids contents in bioprimed tomato seedlings indicated a significantly higher amount with T. viride, followed by those bioprimed with T. asperellum, B. bassiana and C-PC extract. CONCLUSION: Thus, our results indicated that biopriming of tomato seeds with beneficial fungal inoculants and C-PC was very effective. The most operative biostimulants were those bioprimed with T. viride and B. bassiana compared to other biostimulants (T. asperellum and C-PC). Therefore, to ensure sustainable agriculture, this study offers new possibilities for the biopriming application as an alternative and ecological management strategy to chemical treatment and provides a valuable basis for improving seed germination.

Biosorption of cyanate by two strains of Chlamydomonas reinhardtii: evaluation of the removal efficiency and antioxidants activity.

Two strains of the chlorophyte Chlamydomonas reinhardtii, a wild type (WT) and a transgenic strain (C.CYN) contained an exogenous cyanase gene (CYN), were used to investigate the growth and cyanate biosorption capability through the analysis of the adsorption equilibrium isotherm. The potential antioxidants activity of the algal strains was also investigated under cyanate concentration. The antioxidants activity of both C.CYN and WT were enhanced by the application of cyanate.Two adsorption isotherm models and the sorption kinetics were used to check the efficiency of the cyanate removal process. The results showed the biosorbent efficiency of Chlamydomonas in the removal of KCNO from aqueous solution. The C.CYN strain has great efficiency to remove cyanate as compared to the WT. The maximum percentage of cyanate removal was 83.75% for the C.CYN and 50% for the WT as treated with 0.8 mg.ml-1 KCNO. The data were adapted to the nonlinear Langmuir model on the basis of the coefficient of determination. The calculated qmax was 0.54 and 0.42 µg.mg-1 for C.CYN and WT which correlated to the experimental one (0.67 and 0.4 µg.mg-1, respectively). Our data highlight the application of the transgenic algal strain toward the removal of highly toxic materials as cyanate.Novelty statement The main objective of this work is to find out an efficient genetically-modified Chlamydomonas strain to remove the highly toxic cyanate compound from contaminated area. Moreover, to evaluate the biosorption ability of this transgenic strain with its wild one via two adsorption isotherm (the Langmuir and Freundlich) models. Also, to estimate the antioxidants activity of these strains under the cyanate toxicity through four different assays.