Journal of Phycological Research
Volume:5 Issue: 2, Sep 2021

This study aimed to investigate the effect of adding an exogenous carbon source on the growth of Scenedesmus obliquus. For this purpose, the impact of three carbon sources, including sodium acetate (two concentrations of 0.01 and 0.02g/l), sodium carbonate (two concentrations of 0.01 and 0.02 g/l), and aeration to supply carbon dioxide on the growth and production of S. obliquus biomass cultured on BBM medium were investigated. Based on the results, all three carbon treatments significantly increased biomass production and microalgae growth compared to the control group (P <0.01). Among the carbon sources studied, the concentration of 0.02g/l sodium acetate had the most significant effect on microalgae growth. Therefore, this treatment uses for the heterotrophic culture of S. obliquus. Aeration treatment also increased the biomass concentration of the microalgae compared to control (P<0.01). This assay showed that S. obliquus was capable of heterotrophic growth using acetate as a carbon source. The results also showed that carbon treatments significantly increased the content of photosynthetic pigments in microalgae (P <0.01). Since pH may affect algal growth, an examination of the pH trend showed that acetate and carbonate treatments significantly increased the pH of the culture medium at the end of the experiment. In contrast, aeration treatment did not affect pH change compared to the control group.

Fungal endophyte associated with algae represents a rich source of bioactive metabolites and biostimulants, which can be used practically in agriculture as biofertilizers. Here, we aimed to study the associated symbiotic fungi collected from intertidal areas of the southern coastlines of the Persian Gulf and Oman Sea. The extracted endophytic fungi were identified based on morphological, physiological, and molecular (based on ITS1-5.8S-ITS4rRNA regions) analyses. 566 fungal isolates were obtained from 190 seaweed segments. Results showed that the genera Aspergillus and Penicillium were the most frequent isolated fungi. The highest frequency of fungal isolates (48.29%) was observed in seaweeds collected from Bushehr province. In vitro, most of the fungal isolates (85%) could grow properly on a PDA medium incorporated with one molar NaCl concentration. Fungal isolates showing the highest resistance to NaCl in vitro assays and with the highest frequency were used as biofertilizer agents to study their effects on the morphological characteristics of Mexican lime seedlings. The inoculation results showed that the fungal endophytes could increase the fitness of Mexican lime seedlings under heat stress by improving morphological attributes.

Caulerpa is a genus of siphonous green algae belonging to Caulerpaceae which consists of about 103 accepted species of tropical to subtropical seas. Recently, some species of the genus have expanded their distribution into more temperate environments such as the Mediterranean Sea. Due to their bioactive compound and secondary metabolites, content species of this genus have many medicinal uses in various countries, especially in some countries such as the Philippines, Malaysia, and Vietnam, which are used as vegetables. The extract of this alga has antibacterial, anti-viral, and anti-inflammatory properties. Due to this economic and scientific importance, accurate identification of these species is very important. Morphological similarities between some species of this genus and phenotypic changes caused by ecological factors have caused some complications and problems with inaccurate identification at the species level. For this reason, in addition to morphological features, phylogenetic analyzes are also used to accurate identification of the members of this genus. In this study, a molecular phylogeny was inferred from chloroplast tufA sequences of 35 taxa, which of them a sequence of Caulerpella ambigua used as an outgroup. The results confirmed the presence of Caulerpa selago in the algal flora of Iran which is the first record of this species from the coastlines of the Persian Gulf and Gulf of Oman in the south of Iran.

In today's modern world, using water by man and different industries produces a large volume of effluents and wastewaters that are a serious threat to humans, environments, and ecosystems. Refining and treatment of the wastewaters are essential. This research investigated the potential of marine microalgae Fischerella sp. in refining nutrients from wastewater. Fischerella sp. was collected from the Caspian sea.Artificial wastewater was prepared by adding different amounts of NaCl (1, 5%), CaCl2 (35, 100 mg/L), MgSO4 (75,150 mg/L), NaNO3 (50, 2000 mg/L) and K2HPO4 (6,500mg/L) to BG110 medium in 12 runs according to Design expert. The growth and chlorophyll contents in various treatments were measured, and nutrient analysis of the medium was performed on the 10th and 20th days after algal culture. Results showed that maximum growth, chlorophyll and decreasing of Ca2+, Mg2+, NO3- and PO43-content were observed in 1% NaCl,35 and 100 mg/L CaCl2, 150 mg/L MgSO4, 2000 mg/L NaNO3 and 6,500 mg/L K2HPO4 . The most removing activity was shown in the stationary phase of algal growth. Also, these conditions observed a decrease in TDS, TOC, and COD. It can be concluded that Fischerella sp. is a suitable microalga decreasing nutrients in1% NaCl and the highest amount of N and P.

In this study, 17 heterocystous cyanobacterial strains were investigated for biomass density, lipid content, lipid productivity, and fatty acid composition. A superior strain for biofuel production was selected for a further study evaluating the lipid enhancement under some environmental stress including different concentrations of NaCl, H2O2, and CuSO4. Moreover, Real-time PCR analysis determined the dependency of cyanobacterial cell age and also stressed conditions on the expression variations of some essential genes in lipid biosynthesis pathways, and photosynthesis. Among the studies strains, Aliinostoc sp. produced the highest chlorophyll (19.79 µg/mg DW) and lipid (12.64% DW) content, therefore it was selected to optimize experimental conditions for lipid biosynthesis; The optimal conditions for lipid production (CuSO4:3 µm, NaCl:10 mM, H2O2:0) resulted in an increase in lipid (12.82%) and a decrease in chlorophyll (10.32%) content, compared to the control condition. These results were confirmed by up-regulation of the accD gene (73%) as the first gene involved in the lipid production pathway, and down-regulation of the rbcL gene (54%), which is an indicator of photosynthetic rate. Since the ability of growth and lipid production of Aliinostoc sp. has been optimized under salinity and heavy metal stress conditions, lipid production could simultaneously perform by biorefining of contaminated water resources.

Astaxanthin and β-Carotene are well-known carotenoids globally, covering more than half of the market demand for carotenoids. Haematococcus pluvialis microalgae are one of the most important sources of natural astaxanthin, consisting of up to 4% of its dry weight. The most critical challenge for this microalgae is the breakdown of the wall and the extraction of the pigment. In this study, chemical methods, including acid, acetone, and ionic solution, and physical processes such as ultrasound waves and magnetic stirrer, were used to break down the cell wall and measure total astaxanthin in H. pluvialis, respectively. Due to the rapid oxidation of the pigment, in the next step, to extract and store astaxanthin from damaged cells, use olive oil. A spectrophotometer examined astaxanthin, monoester, and diester derivatives, and their amount was determined by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The results showed that using acid treatment, ultrasound waves, and extraction by acetone is the best method to measure the amount of astaxanthin in the algae. The HPLC results also showed that the amount of astaxanthin monoester (88.44%) was higher than the free forms (3.76%) and diester (7.82%) in the total content of extracted astaxanthin. In addition, the amount of total astaxanthin in the H. pluvialis was about 1.6% of the dry weight of the algae