Journal of Phycological Research
Volume:3 Issue: 1, Jun 2019

In this study, the cultivable algae in the coasts of Guilan province in the south west part of the Caspian Sea were isolated, purified and then morphologically and molecularly identified in February 2016. The separated samples were examined by optical microscopy and morphological analysis. Then, 18S rDNA gene primer pair was used for green algae polymerase chain reaction. Totally, 14 algae strains were identified. Among them, four strains were related to the algal branch of Chlorophyta. Considering the importance of the Caspian Sea as one of the largest aquatic habitats in the country, many studies have been conducted on the identification and study of phytoplankton and algae of the Caspian Sea. The seasonal variation of phytoplanktons in the southern basin of the Caspian Sea was studied. During a winter season, 31 species belonged to the Chlorophyta among 32 study stations. The results of this research show that the growth and diversity of the algae in the habitats is affected by seasonal fluctuations and changes in environmental factors such as temperature, salinity, food level, type of bed (due to spread range of sampling area) and a combination of them. In general, research has shown that some factors such as salinity, temperature, source of nitrogen and ambient oxygen, pH, heavy elements, UV rays and other environmental stressors affect the chemical composition and antioxidant activity in algae.

The effect of physical and chemical factors on the species diversity, distribution and density of blue-green algae was examined along the Nour shore of the Caspian Sea. Sampling was seasonal conducted during four sampling campaigns along four transects (A, B, C, D) each bearing three sampling sites (from 1 to 3) in February May, July and November 2014. As a result, 13 species of Cyanophyta division belonging to nine genera, were identified. The highest cyanophyte cell density was observed in summer, when 38 × 105 cells l-1 was noted. However, the results of variance analysis illustrated that there is no significant difference between Shannon’s diversity index in different season (P<0.05 and F=0.521). The spatial distribution of blue-green algae was non-uniform along the shore in the study area, but, along transects, the results proved that the highest density was usually at the first stations of each transect, except C. The most favorable conditions for blue-green species growth were in late spring and summer, when the water temperature increased. In addition, the environmental variables such as salinity and nutrients, especially, phosphates affect the species diversity, distribution and density of blue-green algae in the investigated area according to the Pearson correlation and linear regression.

Different salt concentrations are found in the large portion of water resources and ‎agriculture lands in which most of the plant species cannot be grown. Some microalgae species can be grown either in seawater or in brackish water which is not usable for normal agriculture. The present study analyzed the gene expressions associated ‎with salt stress in Dunaliella Salina. The expression of three coding genes namely ‎acetyl-CoA carboxylase (ACC), channelrhodopsin-1 DChR1 protein (DC), and sodium-coupled phosphate transporter protein (DSSPT) were evaluated at three salinity levels: 3 gL-1 (low), 32 gL-1 (control), 100 gL-1 (high)‎. The analyzes were performed on the 5th, 10th and 17th day of culture. The results revealed that for Low and high salt treatments, the lowest gene expressions were observed on the 5th day of growth, however, the gene ‎expressions were increased with the growth of algae cells until the ‎‎10th day. It should be noted that, under low salinity conditions (3 gL-1), gene ‎expressions were lower than high salinity concentration (100 gL-1) and (32 gL-1) control during the growth.

The present study was conducted to investigate efficacy of unicellular microalga Scenedesmus obliquus either as solo culture or in combination with the bacterium Shewanella sp in removal of arsenic from aqueous media. For this purpose, pure culture of the microalga was fed with arsenic solution and removal rate was monitored. Moreover, impact of pH, temperature and initial biomass was studied. In the second phase, a consortium of S. obliquus- Shewanella was prepared and used to investigate the effect of bacterium presence in terms of removal enhancement. The results showed that pH 7.0, temperature of 29 oC and initial biomass of 0.8 g/L caused the highest rate of arsenic removal. Comparison of pure culture of S. obliquus and S. obliquus- Shewanella consortium revealed that the latter significantly enhanced removal efficacy.

Petroleum is known as the main source of fuel and one of the most important environmental pollutants. Petroleum contaminated soil negatively influences plant growth and human health. Bioremediation of petroleum-contaminated soil could be achieved by adding cyanobacteria and photosynthetic microalgae in the soil. In the current study, the beneficial effects of cyanobacterium Phormidium sp. ISC108 treatment on seed germination and plant growth parameters were investigated on berseem clover plants exposed to 1% hexadecane- contaminated soil. For this purpose, after cultivation of berseem clover seeds in soil with 0 and 1% hexadecane, they were irrigated every two days by 3 ml Phormidium (OD600 = 0.7) and water for the cyanobacteria treatment and control, respectively. After 30 days, the biodegradability of hexadecane in the soil around the root was measured by gas chromatography mass-spectrometry (GC-MS). The results showed that Phormidium treatment accelerated germination of berseem clover seeds in both control and hexadecane- contaminated soil. Improvement of plant growth indices such as leaf area, plant fresh weight and leaf RWC due to cyanobacteria treatment was observed in hexadecane-contaminated soil. Hexadecane levels in the soil around the root of the plants irrigated by cyanobacteria were significantly decreased. In addition, the hexadecane degradation in the soil around the roots of berseem clover plant was increased in both control (water) treatment. In conclusion, due to positive effects of Phormidium treatment on seed germination, plant growth of berseem clover and hexadecane degradation, it can be effectively used to enhance plant capacity to cope with hexadecane toxicity in petroleum-contaminated soils.

In the present study, the optimization of immobilization structures along with Scenedesmus sp. and the determination of heavy metals (Ni, Cr) absorption rate have been investigated. Polymers in combination with salts were performed in alginate in order to study the stability of formed structures in cross linking agents. Beads with stable structure in synthesized heavy metal solution inoculated and the adsorption percentage has been recorded. Results showed that the most stable beads were formed in 2 and 3% alginate along with CaCO3 application beside BaCl2 as solidified solution. Reduction of heavy metal in these structures had the most percentage and it was observed that if the incubation time of beads in solidified solution decreased, the percentage of heavy metal reduction would increase to 86%. Although alginate beads showed the highest absorption rate of heavy metal, the presence of S. sp. in all treatments occasionally increased heavy metal absorption up to 15%.

Soil salinity gradually become a major problem in arid and semi-arid regions of the world. Seed coating through bio-materials is a new method that maintains humidity around the seed. The aim of this study is to use absorbing bio-compounds to increase the percentage of germination and improving growth of Zea mays L. under salt stress. The experiment was conducted with maize seed which coated with tragacanth, tragacanth + Anabaena and tragacanth + Pseudo anabaena when exposed to 0, 120 and 160 mM NaCl per kg of coco-peat. All seed treatments effectively promoted seed germination percentage in 160 mM NaCl. Seed coating with tragacanth led to a significant increase of growth indices compared to the non-coated seeds under salt stress. While, the combination of tragacanth with Anabaena or Peusodoanabaena reduced the growth parameters. Coating treatment of maize seeds resulted in decreasing of Na content in the plants compared to the plants from non-coated seeds. The results suggested that maize seed coating with tragacanth could improve Na tolerance in the plants associated with a positive regulation of the seed germination and plant growth.