جستجوی مقالات مرتبط با کلیدواژه « green algae » در نشریات گروه « زیست شناسی »

Seaweed is a rich source of natural antioxidants. There are large populations of Ulva and Sargassum on the southern coasts of Iran. In this study, populations of green alga U. fasciata Delile and brown alga S. vulgare C. Agardh were collected from Bushehr coasts in winter and spring, and their total phenols and flavonoids were evaluated. Various extracts of these species were prepared and their antioxidant activities were investigated by ABTS and DPPH methods. The results showed that S. vulgare had the highest phenols and the lowest flavonoids contents in spring at 0.62±0.065 and 0.83±0.088 mg g-1 of algae, respectively, and U. fasciata contained the highest flavonoids and the lowest phenols in winter (1.65±0.21 and 0.28±0.04 mg g-1 of algae, respectively. In all extracts, S. vulgare showed higher antioxidant activity than U. fasciata. Both species did not show significant differences in antioxidant activity in winter and spring. The 80% ethanolic, methanolic and boiling water extracts showed higher antioxidant properties than the pure ethanolic, methanolic and distilled water extracts, respectively. The highest and the lowest antioxidant activities were mostly observed in the acidic and ethanolic extracts, respectively. The results will greatly help in the selection and application of algae in the food and pharmaceutical industries.

The aim of this study was to assay the antibacterial activity of Scenedesmus obtusus on some pathogenic bacteria. Microalgae S. obtusus were obtained from Algae Bank of Iran, and the methanol, ethyl acetate, chloroform and n-hexane extract of the microalgae were prepared using the maceration method. Bacterial strains were cultured in a solid culture medium, and antibacterial activity of the the different extracts of S. obtusus, were investigated using well diffusion method, and the determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), against Staphylococcus aureus, Streptococcus agalactiae as gram-positive bacteria and Escherichia coli and Klebsiella pneumonia as gram-negatives. According to the results, methanolic and ethyl acetate extracts of S. obtusus, showed growth inhibitory effects against all examined bacteria at concentrations of 200, 300 and 400 mg/ml. The chloroform extract was effective only against S. aureus and E. coli, but n-hexane extract had no effect against any of the bacteria. The highest inhibitory effect of S. obtusus extract was observed on methanolic extract against E. coli (16 mm), while the least inhibitory effect belonged to ethyl acetate extract against S. aureus (6.8 mm). The results also showed that the extract of S. obtusus contains antibacterial compounds, and the solvent which used for microalgae extraction significantly affected the antibacterial potential of the extract.

Aspergillusniger is one of the microorganisms that produce the pectinase enzymes group of the at high levels. In this fungus, PgaA genes code Glycoside hydrolase family 28 that secrete polygalacturonase enzymes. Green algae (Chlorophyceae) and blue-green algae (Myxophyceae) having pectin, cellulose and hemicellulose compounds such as xylan, arabinoxylan in their structure could act as a precursor to the production of cellulase, xylanase and pectinase enzymes in fungi. In this work, the effect of green algae extract ; Spirogyra sp. at 500 and 1000 mg/mL concentration on the rate of pectinase enzyme secretion and the relative expression of PgaA gene at 4 and 8 day after adding algae extract to culture medium was evaluated using qRT-PCR analysis. . The highest level of enzyme secretion was observed at 8th days after algae extract adding to culture medium at 1000 mg/mL concentration( 4.28 U/ml). Gene expression analysis of PgaA gene showed that the highest expression level was relted to 4th days time interval after adding alge extract at 1000 mg.mL (10/142). According to positive effect of spirogyra algae compounds on expression level of PgaA gene responsible to pectinase production and increase of enzyme secretion, it is concluded that microalgaes could be used as important sources of enzyme production from favorable fungi and could be useful in biotechnological industry

The ability of green microalgae, Dunaliella salina for existence, growth, nitrat reductase activity and ammonium release in low light, ambient CO2 and saline condition was studied for a better understanding of it is biotechnological importance. Samples were cultivated in Johnson medium whit NaCl, 7.5, 15, 30 and 50% or without NaCl(control), 30◦C±1◦C, continious white light, 1500 lux, provided by fluorescent lamps and were aerated continiously using aquarium pumps. Based on the results of the present research, the best growth obtained in NaCl 7.5% for along term period, although in short term, a very high growth rate was obtained in NaCl 50% (Saturated salinity). Ammonium release was maximum in NaCl 50% and the nitrate reductase activity was minimum in the same salinity but there was no statistically significant correlation between ammonium release and nitrate reductase activity. The ability of Dunaliella salina in releasing high amount of ammonium and growth in low and high salinity makes it an important candidate as a new biofertilizer.