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The integration of taxonomic and ecological traits is a more balanced approach in the systematic identification of living organisms. We isolated ten strains of Dunaliella from different geographical regions of Iran, including six terrestrial and four aquatic taxa. All strains belonged to the section Dunaliella based on the morphological and molecular investigation. First, optimal salinity was determined for bio-pigment accumulation. Each alga had its own optimum salinity, and the range of 1.5 to 2.5 M NaCl was further studied. Dunaliella parva YzS produced the maximum biomass density (231.92 mg L−1), while Dunaliella salina MrL accumulated the highest value of total carotenoid (1.72%AFDW). At the early stationary growth phase, the algae had a 11.7 to 41.7% lipid content. FAMEs varied from C10 to C24 with one or more double bonds. The results showed highly significant levels of palmitic (C16) and α-linolenic (C18:3n3) acids. According to the fatty acid profiles, the clustering pattern aligns with the sample origin. Compared to aquatic strains, terrestrials were more resistant to harsh conditions, e.g., dry conditions due to the synthesis of very long chain fatty acids. Lipid compositions may therefore be attributable to the environmental origins of taxa. The fatty acid composition was affected by the environmental conditions, while the accumulation of carotenoid was dependent on the biological and genetic entity of algal taxa. Examination of habitat parameters revealed that aquatic strains were well adapted to maintain homeostasis in higher salinity and conductivity; terrestrial strains were much better able to tolerate high concentrations of nitrate and phosphate.

Cadmium (Cd) is a widely distributed pollutant that adversely affects plants’ metabolism and productivity. Phytohormones play a vital role in the acclimation of plants to metal stress. On the other hand, phytohormones trigger systemic resistances, including systemic acquired resistance (SAR) and induced systemic resistance (ISR), in plants in response to biotic interactions. The present study aimed to investigate the possible induction of SAR and ISR pathways in relation to the hormonal alteration of barley seedlings in response to Cd stress. Barley seedlings were exposed to 1.5 mg. g− 1 Cd in the soil for three days. Cd accumulation resulted in a reduction in the nutrient content of barley seedlings. The specific activity of superoxide dismutase and the content of hydrogen peroxide significantly increased in response to Cd toxicity. The content of abscisic acid, jasmonic acid, and ethylene increased under Cd exposure. Cd treatment resulted in the upregulation of NPR1, PR3, and PR13 genes in SAR pathways. The transcripts of PAL1 and LOX2.2 genes in the ISR pathway were also significantly increased in response to Cd treatment. These findings suggest that hormonal-activated systemic resistances are involved in the tolerance of barley to Cd stress.

Aras Dam Lake is a strategic aquatic ecosystem in Iran and there are reports of toxic phytoplankton blooms in this reservoir. This study was performed to determine the effect of meteorological variables on the formation and expansion of toxic phytoplankton communities in Aras dam reservoir. The data of this project have been obtained using field studies and satellite data (MODIS and Sentinel-2). Sampling to determine the composition of phytoplankton communities in the area was carried out seasonally in two time periods from 2003 to 2014, and environmental assessments were also performed based on meteorological and satellite data over an 18-year period (2003-2020). The Chlorophyll-a content was obtained from MODIS and correlated with meteorological data. The statistical analysis showed that the highest coefficient of determination is related to the correlation of chlorophyll-a and Evaporation (

Background: Microalgae are the source of various compounds with high potentials for being used in different industries. The production of such compounds can be raised under extreme conditions. In the present study, four cyanobacteria and one coccoid green alga were examined which were isolated from hot springs in high background radiation areas in Ramsar, a city in the north of Iran. Methods: Cadmium adsorption from aqueous solution, response towards cadmium stress, antioxidant activity, total phenolic compound and drought tolerance were investigated in these microalgae. Results: The results showed that these extremophile microalgae contain valuable biological compounds which can be useful in remediation of heavy metals from contaminated water and soils and pharmaceutical applications. The unicellular cyanobacterium, Chroococidiopsis thermalis IBRC-M50002, was the best strain with the highest biological activity in various testes such as cadmium adsorption (225 mg g-1), cadmium tolerance stress (100 mg ml-1), antioxidant activity (IC50= 18 μg mg-1) and total phenol content (100 μg ml-1). The coccoid green algae Grasiella emersonii IBRC-M50001, also exhibited significant antioxidant activity (IC50=10 μg mg-1) and total phenol compound (116 μg ml-1), but its cadmium adsorption, tolerance at cadmium stress and desiccation were lower than Chroococidiopsis thermalis. Conclusion: HBRAs microalgae, isolated from extreme conditions, are useful microorganisms for the production of bioactive substances and natural antioxidants. In other words, they exhibited high capacity to be used in pharmaceutical, industrial and commercial applications.

The cyanobacterial species used in this study were collected from medicinal plant beds and were cultured using nitrate free BG-11 medium. As heterocystous cyanobacteria fix atmospheric nitrogen and some of them additionally produce phytohormones, we hypothesized that using a suspension of beneficial cyanobacterial species in the soil of the plant might enhance its growth and would probably also affect the essential oil of this plant. Based on a seedling growth test, the cyanobacterial species Nostoc carneum, Wollea vaginicola and Nostoc punctiforme were selected for a pot trial. A glasshouse experiment with seven replicates was designed to evaluate the effects of the cyanobacterial suspensions on Matricaria chamomilla L. growth and essential oil production. The cyanobacterial suspensions were applied 15 days after planting. Fifty days after flowering the plants were harvested and the plant growth parameters were measured. Additionally, the chemical composition of soil samples from both the treatments and control pots were analyzed. All of the studied cyanobacterial suspensions had a significant effect on the weight of essential oil as well as on root growth. The chamazulene content of the essential oil in plants treated with N. carneum was 26.9% more than in the control. HPLC analysis revealed that the cyanobacterial species used in this experiment were able to produce plant growth–promoting hormones such as indole 3-acetic acid, indole 3-propionic acid and indole 3-butyric acid. There was a significant positive correlation between cyanobacterial IAA and all of the growth factors, as well as some constituents of the essential oil.

Biomass-based decontamination methods are among the most interesting water treatment techniques. In this study, 2 cyanobacterial strains, Nostoc punctiforme A.S/S4 and Chroococcidiopsis thermalis S.M/S9, isolated from hot springs containing high concentrations of radium (226Ra), were studied to be associated with removal of radionuclides (238U and 226Ra) and heavy metal cadmium (Cd) from aqueous solutions. The adsorption equilibrium data was described by Langmuir and Freundlich isotherm models. Kinetic studies indicated that the sorption of 3 metals followed pseudo-second-order kinetics. Effects of biomass concentration, pH, contact time, and initial metal concentration on adsorption were also investigated. Fourier-transform infrared spectroscopy revealed active binding sites on the cyanobacterial biomass. The obtained maximum biosorption capacities were 630 mg g−1 and 37 kBq g−1 for 238U and 226Ra for N. punctiforme and 730 mg g−1 and 55 kBq g−1 for C. thermalis. These 2 strains showed maximum bi...

In this study, 26 Cyanophyta and Chlorophyta microalgae were isolated from high-background radiation areas in Iran. Among them, one green alga showed the highest radionuclide sorption capacity. This uranium- and radium-resistant microalga belongs to the genus Graesiella, and based on its morphological and molecular characteristics, it was identified as Graesiella emersonii Shihira and R.W. Krauss. The sample was isolated from the Ab-e-Siah hot spring in Ramsar (a city in northern Iran) with a 226Ra content of 130 Bq L−1. This strain exhibited maximum sorption capacities of 69 kBq g−1 of 226Ra and 530 mg g−1 of 238U. The optimum conditions for removal of the radionuclides were determined, and the results showed that the pH and initial cell concentration significantly affected radionuclide sorption. Furthermore, the experimental data were well-fitted to the Langmuir isotherm and pseudo-second-order kinetic models. FT-IR spectra and SEM analyses showed the mechanisms of the sorption process. The results of the present study indicated that the green alga G. emersonii, can serve as an appropriate candidate for designing an efficient sorption system for an area contaminated by 226Ra and 238U radionuclides.

This study was undertaken to determine the phytoplankton structure and the environmental variables comprising the driving factors leading to cyanobacterial blooms in Aras Reservoir. Sampling was carried out seasonally at five sampling sites along the main body of the reservoir. Samples were collected for phytoplankton identification and enumeration, chemical analyses and chlorophyll-a (Chl-a) concentrations at each sampling site. Principal component analysis (PCA) and two-way unweighted pair group method with arithmetic mean (UPGMA) were performed to determine the environmental variables affecting phytoplankton community dynamics. Seventy-two species belonging to five divisions were determined during this study. Cyanobacteria contained the highest density (74%) during the study period, with Pseudanabaena limnetica being the most abundant species. The Shannon diversity index was low (0.44–1.87), indicating a high level of cyanobacteria dominance and eutrophic water status. Principal component analysis indicated that total phosphorus and temperature were significantly associated with cyanobacteria growth. Two-way clustering by UPGMA indicated a close relationship among sampling sites during the same season from the perspective of the phytoplankton density. The findings of this study suggested Aras Reservoir could be highly affected by agricultural runoff and untreated sewage loadings. Thus, the proper use of fertilizers and sewage treatment should be taken into account in considering effective conservation and management plans.

Extracts of four heterocystous cyanobacteria isolated from wheat field soils (Triticum aestivum L.) were used as a promoter of growth and essential oil production in Mentha piperita L., which is mostly used for medicinal purposes. An axenic monoalgal culture was prepared using nitrate-free BG-11 medium. Pot experiments were performed by spraying algal extracts on the soil of treated plants on the first day of planting and every 20 days thereafter. Growth of plants was evaluated by measuring growth parameters such as plant height, root length, dry and fresh weight of plant, as well as leaf number, leaf area, and ramification after 100 days planting. In addition to growth factors, the quantity of essential oil of plants was also assessed. Statistical analysis showed that there were significant differences in the studied parameters compared to the control. The addition of some cyanobacterial inocula had a positive effect on the plant growth parameters and essential oil content. HPLC analysis of the cyanobacterial extracts detected some auxins, which may be the possible factor contributing to the positive growth responses and enhanced essential oil content of the treated plants.

Large amounts of synthetic nitrogen fertilizers for microalgal growth and low productivity of microalgae-based processes are fundamental issues in commercialization of biofuels derived from microalgae biomass. The present work was undertaken to benefit the nitrogen-fixing ability of heterocystous cyanobacterium, Anabaena vaginicola, as a substitute of nitrogen fertilizer for culturing Chlorella vulgaris and Nannochloropsis oculata. The results indicated that the microalgae could both assimilate the nitrogenous extract of A. vaginicola as the only nitrogen source of the medium and utilize organic carbon content of the extract in mixotrophic growth. Presence of phytohormones in the extract of A. vaginicola was also detected which might offer a potential to enhance microalgal productivity. The strategy of utilizing the cyanobacterial extract in the growth medium improved biomass and lipid productivity of the microalgae. Biomass concentrations of the microalgae in the media with the extract as an alternative to nitrate increased significantly (p ≤ 0.05) compared to the control media, being 2.80 g L−1 for C. vulgaris nearly twice the value in the control medium, and 2.99 g L−1 for N. oculata almost 2.3 times higher than the value in the control medium. Lipid productivity of C. vulgaris and N. oculata increased by 2.68 (97.28 mg L−1 day−1 vs. 36.21 mg L−1 day−1) and 3.40 (145.43 mg L−1 day−1 vs. 42.76 mg L−1 day−1) times, respectively, in the extract supplemented media as nitrate substitute relative to the control media. The extract provided nutrients required for culturing the microalgae and supported growth without addition of other nutrients to the growth medium. Supplementation of the extract to the media could also favorably manipulate the fatty acid composition of the microalgae, resulting in fatty acid profiles rich in saturated fatty acids and monounsaturated fatty acids with lower levels of polyunsaturated fatty acids.

Although much attention has been paid to study of nitrogen fixation by blue-green algae in paddy fields, algae are also beneficial for plant by producing plant - growth promoters like auxins, cytokinins, abscisic acid and ethylene. Monoalgal cultures was carried out by growing the isolates in nitrate free BG-11 medium in two liter container at 24° and a 12/12 h light-dark cycle at artificial illumination (2,000-2,500 Lux) with constant stirring and aeration. After three weeks culture was harvested and used as an inoculum. Five healthy seedlings were grown in 1 liter pots (14 cm diam.) including 60% peat, 25% sand and 15% normal soil. No fertilizer was applied, but 400 milliliters algal suspension (OD=0.3) was sprayed on treated and BG-11 medium for untreated pots. The pots were arranged in a completely randomized design in an experimental greenhouse. Growth of plants was evaluated by measuring plant height, root length, number leaf and flowers after 50 days planting. From the results described in this paper, it is clearly showed that the algal culture contained some substances that can promote growth of the plants. Result of this finding also has led to the recognition that addition of algal inoculums positively affected plant height and plant root length.

In this research heterocystous cyanobacteria were isolated from paddy soils and used as algal extracts in a pot culture of vegetable crops. The first aim of this research was to study the distribution of algal species isolated from different rice (Oryza sativa L.) cultivation regions of Iran. Soil samples were collected from seven main rice cultivation provinces situated in perhumid and semi-arid regions of the country. In total, 49 heterocystous morphospecies were isolated from 20 locations. Among these taxa, Anabaena and Nostoc were found to be the dominant genera at most stations. The effect of algal extract on vegetable crops was the second aim of this experiment. After isolation and identification of these taxa, monoalgal cultures of two isolates were carried out by growing the isolates in nitrate-free BG-11 medium. Pot experiments were carried out by spraying algal extract on soil of treated plants. Growth of plants was evaluated by measuring growth parameters such as plant height, root len...

Four major carotenoids of high nutritional significance, including β-carotene, lycopene, lutein and zeaxanthin were determined in three isolates of heterocystous cyanobacteria, belonging to the genera Anabaena and Nostoc, isolated from Iranian terrestrial and aquatic ecosystems, for the first time. The ultrasonically extracted carotenoids were identified and quantified by a rapid and sensitive isocratic HPLC method and identification was further confirmed by spiking authentic standards and the pattern of the UV-Vis spectra obtained from photo-diode array detector. The results showed that these isolates contain large amounts of four major carotenoids, especially lycopene (up to 24,570 μg/g dry weight, DW) which appears to be the highest reported amount until present; and β-carotene (up to 8133 μg/g DW) which is comparable with the best natural sources of β-carotene. Meanwhile, they are rich in the cis-isomers of lycopene and β-carotene which is important in their bioavailability and health benefits.

Three isolates of heterocystous cyanobacteria, belonging to the genera Anabaena and Nostoc, gathered from Iranian terrestrial and aquatic ecosystems exhibited considerable growth promotion effect on several vegetables and herbaceous plants. To study the ability of these three isolates to produce auxins, three endogenous auxins, including indole-3-acetic acid (IAA), and two of its main homologues, indole-3-propionic acid and indole-3-butyric acid, were extracted and analyzed with high-performance liquid chromatography equipped with diode array detector and fluorescence detector, and the results were further confirmed with liquid chromatography–tandem mass spectrometry (LC–MS/MS) in the negative-ion mode. The dominant auxin observed in all isolates was indole-3-butyric acid (IBA) in the range of 140.10–2146.96 ng g−1 fresh weight (FW), and only small amounts of IAA (2.19–9.93 ng g−1 FW) were detected. The predominance of IBA in these strains is reported for the first time which is different from the previously reported auxin profiles in microalgae and algae with the predominance of IAA.