Journal of Phycological Research
Volume:4 Issue: 1, Jun 2020

Applications of seaweeds as food ingredients and bioactive compounds are increasing these days. Many of seaweeds have to be evaluated for these purposes. This study investigated the biological activities of organic extracts of four green and a red macroalgae collected from the coast of Bandar Abbas, Iran. After species identification, the bioactivities of seaweeds have been studied by antioxidant assay (Ferric reducing power and total antioxidant capacity), total phenolic and flavonoid contents, antibacterial activity, and brine shrimp cytotoxicity activity on model organism, Artemia salina (Linnaeus, 1758) and Artemia franciscana (Kellogg, 1906) were anaysed. The results revealed the most effective algal extracts by maximum antioxidant capacity were recorded using methanol extracts of Ulva intestinalis Linnaeus 1753, and Ulva clathrata (Roth) C. Agardh 1811. In addition, the highest content of total phenolic content was recorded by green seaweeds. While, the highest flavonoid content was obtained from Gracilariopsis persica Bellorin, Sohrabipour & E.C. Oliveira. Most extracts showed significant antibacterial effects, with disk diffusion method. Among the various extracts, the n-hexane extract was found the highest zone of inhibition against analyzed pathogenic bacteria. U. intestinalis and U. clathrate have a better antimicrobial activity and are a potential source of antimicrobial compounds. Further, we found a best toxic effect to A. salina in n-hexane extract of G. persica, LC50 =125 μg/ml. Generally, the findings can be introduced the green seaweeds as priority species for biological properties and can be subject of isolation of the natural antimicrobials.

The diatoms are widespread organisms that occurred in various environments like soil, marine, freshwater, and even in extreme conditions. Taleqhan River is one of the main tributaries of Sepid Roud, the second longest river in Iran with approximately 670 km length.  During the sampling from eight stations in the Taleghan River and Dam, Pinnularia lundii var. linearis Krammer was identified as a new record for diatoms flora of Iran. Given the importance of Pinnularia genus as an indicator of pollution, it was discussed together with Pinnularia brebissonii (Kütz.) Krammer in this paper. This study was performed during November 2017 to October 2018 on the sediments monthly in the North of Iran. The most characteristic morphological features were the valve outline, density of striae, hexagonal-shaped central area, non-deflected proximal raphe endings and capitated apices. The most similar species to this taxon are P. subanglica Petersen and Pinnularia biceps Gregory. They have deflected proximal raphe ending, unlike Pinnularia lundii var. linearis.

This study was aimed to investigate the possible exploitation of phototrophic microorganisms for the oxidation of Au3+ containing composites as well as recovery and bioaccumulation of Au3+ from Mouteh goldmine soil samples. Mechanisms of accumulation including oxidation, dissolution, reduction, leaching and sorption were investigated. After 3 weeks of cyanobacterial growth, gold bioaccumulation from Mouteh gold mine soil solution were determined. Then biomass digested with acidic solutions and subsequently gold amounts were analyzed with Atomic Absorption Spectroscopy. Soil sample with 2 ppm Au3+containing composites ore from Mouteh goldmine were collected. At the end of experiments, the concentration of gold in biomass was almost 6.5 ppm. Results indicated that two soil cyanobacteria species from Mouteh goldmine could bind gold in gold bio-mining process. Bioaccumulation percent was 32% and 30% for Phormidium tenue Gomont and Osillatoria tenuis C. Agardh ex Gomont respectively. Cyanobacterial gold accumulation were determined 6.5 gr/kg biomass dried weight. 

Urmia Lake is one of the largest permanent hypersaline lakes in the world. The lake can be characterized as an oligotrophic lake concerning phytoplankton production. Due to agriculture development and low precipitation in recent years in Urmia Lake’s basin, the water level has declined as much as 4 m compared to 15 years ago. Water level decline influence the phytoplankton population through increased water salinity. Furthermore, Artemia urmiana Gunther as the major zooplankton in hypersaline lakes may affected on phytoplankton populations. Therefore, the purpose of the present study was evaluation how A. urmiana impact on the phytoplankton structure in Urmia lake. Eight stations were selected in south and north parts of the lake. Sampling were performed monthly during May 2018 to June 2020. Phytoplankton structure were analysed by inverted microscopy. Environmental parameters water temperature, pH, salinity, water level, Total Dissolved Solids (TDS), Electric conductivity (EC) were determined in each sampling. Seasonal fluctuations of algal abundance influence A. urmiana population in temperate large hypersaline lakes such as Urmia Lake. However, A. urmiana grazing pressure has significant effects on microalgal density. This study indicated that salinity is not increased directly by water level decline in Urmia Lake. 

In the present study, in order to investigate and compare the absorption of heavy metals (nickel, cadmium, lead, and copper) in two algae species, Padina gymnospora Kuetzing Vickers and Padina tetrastromatica Hauck, and in the adjacent sediments along the Bushehr coasts, four sites namely Helilla, Lian, Raphael (burned ship) and Naftkesh were selected for sampling. The sediment and algae sampling was carried out during summer and winter of 2016. After digestion and preparation of samples, an atomic absorption instrument was used to measure the concentration of heavy metals. The mean concentration of Nickel, Cadmium, Lead, and Copper in two samples was measured about 8.91, 1.2, 3.47 and 0.31 μg.g-1 in P. gymnospora, 8.72, 1.15, 3.33 and 0.28 μg.g-1 in P. tetrastromatica and 7.93, 1.61, 2.83 and 0.18 μg.g-1 in studied sediments, respectively. The absorption rate of investigated species and sediments were nickel >copper >lead >cadmium.

In the last decades, biotechnological applications have led to the optimization of the cultural conditions for the production of exopolysaccharides (EPSs) by cyanobacteria. Nostoc is a genus of cyanobacteria found in various environments that forms colonies composed of filaments of moniliform cells in a gelatinous sheath. The effect of some important nutritional and growth beside iron nanoparticles on production by Nostoc sp. was studied. Optimization of the cultural conditions was carried out using Central Composite Design (CCD), and it was achieved at pH 8.39, 1% of NaCl and 0.8 g.l-1 nitrate based in modified BG0 medium and more than 12 g.l-1 of EPS was obtained by phenol-sulphuric acid method. The present research investigated the possibility of inducing EPS production in the presence of Fe3O4 nanoparticles from optimized microalga cultures. This study revealed that Nostoc sp. treatment with 10 mg.l-1 Fe3O4 NPs induced maximal EPS production (4 µg.ml-1).