Awatief F. Hifney
Assiut University
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Featured researches published by Awatief F. Hifney.
Nature | 2001
Egbert Boekema; Awatief F. Hifney; Alevtyna E. Yakushevska; Markus Piotrowski; Wilko Keegstra; S. Berry; Klaus-Peter Michel; Elfriede K. Pistorius; Jochen Kruip
Cyanobacteria are abundant throughout most of the worlds water bodies and contribute significantly to global primary productivity through oxygenic photosynthesis. This reaction is catalysed by two membrane-bound protein complexes, photosystem I (PSI) and photosystem II (PSII), which both contain chlorophyll-binding subunits functioning as an internal antenna. In addition, phycobilisomes act as peripheral antenna systems, but no additional light-harvesting systems have been found under normal growth conditions. Iron deficiency, which is often the limiting factor for cyanobacterial growth in aquatic ecosystems, leads to the induction of additional proteins such as IsiA (ref. 3). Although IsiA has been implicated in chlorophyll storage, energy absorption and protection against excessive light, its precise molecular function and association to other proteins is unknown. Here we report the purification of a specific PSI–IsiA supercomplex, which is abundant under conditions of iron limitation. Electron microscopy shows that this supercomplex consists of trimeric PSI surrounded by a closed ring of 18 IsiA proteins binding around 180 chlorophyll molecules. We provide a structural characterization of an additional chlorophyll-containing, membrane-integral antenna in a cyanobacterial photosystem.
Photosynthesis Research | 2003
Klaus-Peter Michel; Stephan Berry; Awatief F. Hifney; Jochen Kruip; Elfriede K. Pistorius
To learn more about the adaptive response of Synechococcus elongatus PCC 7942 to iron starvation and the role of DpsA, presumably a protein protecting chromosomal DNA against oxidative damage, we performed a comparative analysis of S. elongatus PCC 7942 wild-type and a DpsA-free mutant, called K11. Relative to wild-type, the DpsA-free mutant had significantly higher amounts of phycocyanin and allophycocyanin, even upon iron limitation. While the Photosystem I activity in mutant K11 remained high under iron deficiency, the Photosystem II activity dropped severely with respect to wild-type. The DpsA content in wild-type was already fairly high under regular growth conditions and did not significantly increase under iron deficiency nor in the presence of 0.3 mM 2′2′-dipyridyl in iron-sufficient BG11 medium. Nevertheless, the absence of DpsA in K11 resulted in a significantly altered transcriptional/translational activity of genes known to be involved in adaptation to iron starvation. The amount of isiA/B transcript was about two-fold lower than in wild-type, resulting in a lower 77 K chlorophyll a fluorescence at 685 nm, implying a lower concentration of Photosystem I-IsiA supercomplexes. While in wild-type idiA, idiB, and irpA transcripts were highly up-regulated, hardly any were detectable in mutant K11 under iron limitation. The concentration of mapA transcript, however, was greatly increased in K11 compared to wild-type. Measurements of acridine yellow fluorescence with intact wild-type and K11 cells revealed that iron deficiency caused an increased contribution of cyclic electron transport to membrane energisation and ATP synthesis being in agreement with the formation of the Photosystem I-IsiA supercomplex. In addition, mutant K11 had a much higher respiratory activity compared to wild-type under iron limitation.
Hydrobiologia | 2014
Khayria M. Abdel-Gawad; Awatief F. Hifney; Ahmed A. Issa; Mohamed Gomaa
The study of fungal species diversity from marine algae is in its infancy; as now no studies have been carried out on the distribution and diversity of fungi on the surfaces of marine macroalgae where all fungal–algal interactions tend to begin. The aim of this study was to isolate and describe the culturable part of mycobiota associated with the surface of benthic marine macroalgae (epiphytic or epibiotic fungi). This is an important step in understanding their abundance, diversity and factors influencing their variability and composition. The fungal community was dominated by Ascomycetes (89%) with Eurotiales as the most abundant fungal order followed by Capnodiales, Pleosporales, and Hypocreales, while Zygomycetes was less frequent. The nature of occurrence of fungal genera on different macroalgal hosts suggests that a mix of generalists’ framework applies to fungal epiphytes of seaweeds, but the abundance of fungal taxa varied among ecological functional groups of algae, as well as macroalgal taxonomic groups, which imply host filtering. The fungal assemblages were also characterized by temporal variation with variation in temperature, pH, and salinity as the most important abiotic factors. The structure of fungal assemblages showed high beta diversity and low similarity between hosts.
Carbohydrate Polymers | 2017
Mustafa A. Fawzy; Mohamed Gomaa; Awatief F. Hifney; Khayria M. Abdel-Gawad
Alginate was recovered from Sargassum latifolium biomass using different conditions of alkali treatment. Box-Behnken experimental design was evaluated to study the influence of alkali:alga ratio, temperature and time on alginate yield, and its molecular weight (MW) and mannuronic/guluronic acid ratio (M/G). The second-order polynomial equations were analyzed by appropriate statistical methods. Extraction temperature and time were the most important factors during alginate alkaline extraction. MW and M/G ratio played an important role in controlling the reducing power of alginate. Increasing pH of the alginate solutions enhanced its reducing capacity, while thermal treatment showed a negative effect. Additionally, alginate exhibited good emulsion stabilizing capacities with diverse hydrophobic compounds. Emulsifying activity was less sensitive to temperature, ionic strength and more stable at acidic pH.
Botanica Marina | 2014
Ahmed A. Issa; Awatief F. Hifney; Khayria M. Abdel-Gawad; Mohamed Gomaa
Abstract β Diversity is an ecological concept used to describe the turnover of species across a wide range of spatial and temporal scales, but such knowledge is lacking for macroalgal assemblages of the Red Sea. β Diversity patterns for Red Sea macroalgae were evaluated from different sites (Hurghada, Safaga, and Al-Quseir) and seasons across different environmental disturbances. β Diversity was studied by partitioning the total number of species (γ diversity) into additive components. Geographical heterogeneity was more important than seasonal heterogeneity in structuring macroalgae both at species and functional group levels. Species replacement as a component of β diversity produced dissimilarity in species composition and taxonomic structure. Replacement of species between sites was responsible for the presence of new functional groups of macroalgae. High β diversity and taxonomic similarity values were characteristic of the macroalgae of the Red Sea. The occurrence of small macroalgal thalli that have short life cycles induced high species replacement and subsequently high β diversity, with spatial heterogeneity and environmental gradient as drivers of β diversity. Anthropogenic disturbance at the Safaga site was suggested to induce variation of macroalgal assemblages and functional groups. Excluding rare species from the data set did not change the high values of b diversity.
Journal of Aquatic Food Product Technology | 2017
Awatief F. Hifney; Mustafa A. Fawzy; Khayria M. Abdel-Gawad; Ahmed A. Issa; Mohamed Gomaa
ABSTRACT The screening of potential antioxidant activities of hydrophobic (ethyl acetate) and hydrophilic (polysaccharide) extracts from both mycelia and fermentation media of eleven algicolous fungi was performed using three antioxidant assays. Algicolous fungi were able to ferment low-cost nutrients composed of potato infusion, glucose, and natural seawater and produce hydrophobic and hydrophilic metabolites with antioxidant properties. Significant differences were observed in antioxidant activities of extracts from the various species evaluated using total antioxidant activity (TAA), hydroxyl radical scavenging activity (HRSA), and ferric reducing antioxidant power (FRAP), as well as their total sugar contents (TSC) of hydrophilic extracts and total phenolic contents (TPC) of hydrophobic extracts. TSC of endopolysaccharides was higher than exopolysaccharides and showed a significant correlation with both TAA and FRAP. Most of mycelial extracts were richer in phenolics than fermentation media, and TPC of hydrophobic extracts was significantly correlated with their FRAP. Mycelial extracts for most of algicolous fungi showed higher antioxidant activities than fermentation media. Both hydrophobic and hydrophilic extracts of algicolous fungi showed good antioxidant properties, especially as hydrogen-donating antioxidants, which could be considered for future applications in medicine, food production, or cosmetic industry.
Food Chemistry | 2018
Awatief F. Hifney; Mustafa A. Fawzy; Khayria M. Abdel-Gawad; Mohamed Gomaa
The seaweed Cystoseira trinodis was fermented by different fungi prior to extraction of fucoidan and alginate to enhance their antioxidative potential. All the investigated fungi were able to produce fucoidanase (1.05-3.41 U/ml) and alginate lyase (7.27-18.59 U/mL). Different fungal species induced a reduction in the molecular weight (MW) of fucoidan and alginate in comparison to the unfermented control. The MW of fucoidan reduced by 41-81.5%, while the MW of alginate was reduced by 28-75%, depending on the fungal species. Significant increases in the fucose and sulphate contents of fucoidan and mannuronic/guluronic acid ratio of alginate were induced by fungal fermentation. Fungal pretreatment enhanced the ferric reducing antioxidant power, total antioxidant capacity and hydroxyl radical scavenging activity of both fucoidan and alginate. Additionally, enzymatic pretreatment of the macroalgal biomass assisted in the recovery of fucoidan and alginate with low molecular weight and enhanced antioxidative potential.
egyptian journal of basic and applied sciences | 2017
Mustafa A. Fawzy; Dalia A. Abdel-Wahab; Awatief F. Hifney
Abstract The effects of various concentrations of different carbon sources (Na2CO3 and NaHCO3) as sodicity stress on growth parameters, CO2 consumption rate, enzyme activity, intracellular lipid content, and fatty acid profiles of Pachycladella chodatii were studied. Generally, the total chlorophyll was increased by increasing the concentrations of Na2CO3 and NaHCO3. The biomass productivity as well consumption rate of carbon dioxide of P. chodatii reached the highest values with increasing concentrations of Na2CO3 and NaHCO3. The soluble protein content of P. chodatii was highest at the lowest Na2CO3 and NaHCO3 concentrations. The addition of different concentrations of Na2CO3 and NaHCO3 in the growth media induces lipoxygenase and superoxide dismutase specific activity. Catalase and total antioxidant enzymes were increased by supplementing the growth media with 60 and 45 mg l−1 of Na2CO3 and NaHCO3, respectively. Hydrogenase uptake activity in P. chodatii increased gradually in all treated cultures with the time elapsed recording the maximum activity after 11 days of growth especially at 60, 45 mg l−1 of Na2CO3 and NaHCO3 respectively. Lipids content was increased at low concentration of Na2CO3 (40 and 15 mg l−1) and NaHCO3 (60, 45 mg l−1) respectively. Subsequent to algal cultivation in different concentrations of Na2CO3, the cultures were filtered and biodiesel was prepared by direct esterification of dry algal biomass. Methyl esters of palmitic, elaidic and stearic acids represented the major components while myristic, pentadecanoic and 9,12-octadecenoic acids represented a minor component of biodiesel produced from P. chodatii treated with different concentrations of Na2CO3 and NaHCO3.
European Journal of Ecology | 2017
Mahmoud S. Adam; Awatief F. Hifney; Mustafa A. Fawzy; Arwa A. Al-Badaani
Abstract A qualitative and quantitative study on epiphytic microalgae was carried out seasonally from November 2015 to August 2016 to follow up their community structures on aquatic macrophytes related to some physico-chemical properties of two polluted and unpolluted water bodies at Assiut, Egypt. A total of 169 species related to 64 genera of epiphytic microalgae were recorded. The most dominant algal group was Bacillariophyceae (43.2%), followed by Chlorophyceae (34.91%), Cyanophyceae (20.71%) and Euglenophyceae (1.18%). The total number of epiphytic algae fluctuated between 11.1 × 104 ind.g-1 plant dry wt. on Phragmites australis in summer at Nazlet Abdellah (polluted site) and 10.02 × 107 ind.g-1 plant dry wt. on Myriophyllum spicatum in winter at El-Wasta (unpolluted site). Some epiphytic microalgae were dominant as Pseudanabaena limnetica, Calothrix braunii, Scenedesmus acutus, and Ulnaria ulna. Others were specific on certain macrophytes as Aphanocapsa thermalis and Ulothrix sp., which grow on Phragmites australis, while Synechocystis minuscula attached itself on Myriophyllum spicatum. Analysis of PERMANOVA showed that the most important factors that induced the variation in epiphytic microalgae were the temporal variation and host plant. Water temperature, pH, nitrate, chloride, phosphate and total dissolved salts were the highest abiotic factors correlated with the variation in composition of epiphytic microalgae.
Food Hydrocolloids | 2016
Awatief F. Hifney; Mustafa A. Fawzy; Khayria M. Abdel-Gawad; Mohamed Gomaa