Journal of Phycological Research
Volume:6 Issue: 1, Jun 2022

In-vitro antioxidant activities of semi-purified methanolic extract of Lyengaria stellata and Padina boergesenii were evaluated using DPPH radical-scavenging activity and reducing power. Total phenolic contents (TPC) and total flavonoid contents (TFC) were also investigated. The acetone fraction of L. stellata contained the highest value (126.04±8.65 mg GAE/g) of TPC, and the highest concentration of TFC (94±0.13 and 82±0.09 mg GAE /g) was obtained in ethanol fractions of Lyengaria stellata and Padina boergesenii, respectively. The highest DPPH scavenging activity (88.5%) was observed in the acetone fraction of L. stellata (1 mg/ml). The most significant reducing power was observed in the acetone fractions of both seaweeds at 100 mg/ml concentration (1.130±0.040 and 0.839±0.010, respectively). Ethanol and acetone fractions of L. stellata showed the greatest antibacterial activity (29.6±0.5 and 28.0±0.7 mm, respectively) against Staphylococcus aureus. The minimum value of MIC was observed in acetone fractions of both seaweeds against S. aureus (50.7 and 50.8 µg/ml), while Salmonella enterica showed the highest resistance to seaweeds extracts according to the– highest MIC values (>200 mg/ml) and the smallest IZ diameters. The extract of both algae showed considerable antioxidant activity according to DPPH radical scavenging activity and reducing power assays.

The biosynthesis of nanoparticles using microorganisms as emerging bionanotechnology has received considerable attention due to a growing need to develop environment-friendly technologies in materials synthesis. Nanoparticles produced by a biogenic enzymatic process are far superior in biomedical applications to those produced by chemical methods. This study explored the biosynthesis of gold nanoparticles by Arthrospira platensis Gomont. Two series of experiments hence the dose dependency (chloroauric acid solution with different concentrations) and the temperature dependency (room, 75º C, and 90º C temperature) of Au nanoparticles formation, were studied. Optimizing the synthesis of gold nanoparticles and gold nanoparticle concentration determination was done. The results showed that the gold nanoparticles' size is reduced by reducing the gold concentration and raising the reaction temperature. In addition, the size of spherical shape nanoparticles has decreased from 80 nm to 20 nm, and as the concentration increased, nanoparticles became more stable. Extracted nanoparticle solutions were examined by UV-visible Spectroscopy, scanning electron microscopy (SEM), dynamic Light Scattering (DLS), and EDAX or EDS (Energy-dispersive X-ray spectroscopy) analysis. Results indicated that algae extract very suitable for biosynthesis and are more efficient than biomass. The maximum production efficiency with this method is 98%, which is excellent and economical.

Cyanobacteria are a group of prokaryotes that can live under stressful environmental conditions due to their high metabolic flexibility. In this study, we examined the terrestrial cyanobacterial communities in the wheat fields adjacent to the industrial areas of Yazd province. The physical and chemical properties of the soils were evaluated, including pH, EC, salinity, and the concentration of two heavy metals, lead, and cadmium. In addition, the diversity and abundance of cyanobacteria were investigated in the soil of the studied stations. The frequency of taxa was determined based on the colony count method. According to the results, the amount of cadmium was very low (lower than 0.1 ppm), but the lead concentration in the studied stations varied between 1.602 ppm and 4.044 ppm. The sodium concentration in the soil ranged from 16.18 to 89.54 mEqL-1. The present results show that with a slight increase in the concentration of lead in the ground, the diversity of cyanobacteria does not decrease. Still, an increase in the concentration of information from a specific range causes a reduction in their biodiversity. Moreover, the cyanobacteria abundance does not show any significant decrease in this range of lead concentration. This result may indicate the relative resistance of the dominant taxon to lead metal and the development of these taxon communities in stressful conditions.

In this experiment, we compared the antioxidative response and biomass production of three ploidy levels induced by three colchicine concentrations (0, 0.1, and 0.5%) and the effects of different concentrations of two phytohormones (auxin and gibberellin) on D. salina. The fresh and dry weight of algae treated with colchicine significantly increased. Auxin (1μM) and gibberellin (10 μM) caused a further increase in biomass in colchicine-treated algae. Colchicine treatment induced catalase and superoxide dismutase activity, but peroxidase activity showed a decrease under this condition. Auxin only increased the superoxide dismutase activity at concentrations of 10 and 100 µM. The catalase activity decreased in the treated algae with 1 and 10 µM auxin. Different auxin concentrations caused an induction in the mentioned enzymes in the colchicine-treated algae. The most increase was observed in catalase activity by adding 1 µM auxin to the colchicine-treated algae. Gibberellin at concentrations of 1 and 10 µM induced peroxidase, catalase, and superoxide dismutase activity. Gibberellin caused a considerable increase in enzyme activity in colchicine-treated algae. The results show that polyploidy along with phytohormones increases the activity of antioxidant enzymes and thus gives the algae the potential for better stress resistance.

Golestan Dam Lake is located 12 kilometers east of Gonbad City and was constructed in 1379. The volume of the Golestan Dam reservoir is 52 million cubic meters and its area is 1500 hectares, which was built for the purposes of agricultural and aquaculture operations.. The present study on phytoplankton biodiversity and its relationship with the primary productivity of the Golestan Dam reservoir was conducted from April to July 2019. Furthermore, water quality parameters such as transparency, pH, alkalinity, free carbon dioxide, air and water temperature, dissolved oxygen, primary productivity, conductivity, nitrate-nitrogen, and orthophosphate were analyzed along with qualitative and quantitative estimation of phytoplankton. The results indicated that the average primary productivity or Gross primary production (GPP) was 0.399 ± 0.081 gcm3h-1, Net Primary Production (NPP) (0.307±0.061 gcm3h-1), and Community Respiration (CR) 0.094±0.024 gcm3h-1 in the surface. Algae in freshwater have numerous environmental functions and are based upon the recycling of nutrients. Totally 73 species of phytoplankton belonging to the different taxonomic groups were identified. which belong to 32 genera Among these 32 genera, 12 belong to Cyanophyceae,8 belong to Chlorophyceae, 10 belong to Bacillariophyceae, and 2 belong to Euglenophyta. On the basis of mean primary productivity, the fish production potential of reservoir Golestan Dam showed considerable scope for the enhancement of current average production.

Increased biomass density of microalgae is a critical factor in the enhancement of the algal metabolites. In this study, the effects of linoleic acid, TiO2, and SiO2 nanoparticles were investigated as elicitors on the production of biomass, and fatty acids in the microalga, Haematococcus lacustris. Several treatments of TiO2 and SiO2 nanoparticles were analyzed as well as linoleic acid on Haematococcus lacustris in two separate designs. Microalgal biomass in nanoparticles was investigated using the Neobar chamber and in linoleic acid using the freeze-dryer methods. Fatty acids compositions were tested by gas chromatography method and five of them named Palmitic, Palmitoleic, Stearic, Oleic, and Linoleic acids (LA) were measured. The results showed that the biomass significantly increased by LA (30 μM) and TiO2NPs (40 mg/L) treatments, and consequently, these treatments increased the biomass density by 2 and 1.3 times more than the control treatment, respectively. Palmitic and linoleic acids were the most frequent fatty acids produced by 60 and 30µM of LA treatments with 1.4 (53.26 % w/w) and 1.5 (32.51 % w/w) folds, respectively. To conclude, the different concentrations of LA and TiO2NP boosted the production of algal biomass, and some fatty acids in Haematococcus lacustris. Moreover, LA may be used as an effective inducer to increase biomass production in the valuable microalga Haematococcus lacustris.