Temporal variation in chemical composition of Dictyota dichotoma (Hudson) J.V. Lamouroux (Dictyotales,Phaeophyceae) from Red Sea Coast, Egypt

Objective: To relate the chemical composition of Dictyota dichotoma (Hudson) J.V.Lamouroux (D. dichotoma) to variation of water characteristics at Hurghada, Egypt.Methods: Sea water and D. dichotoma fronds were collected from Hurghada shores, during autumn of 2014. Water samples were analyzed and fronds of D. dichotoma were biochemically quantified.Results: Sea water was characterized with high levels of salinity, P and heavy metals but with low content of nitrogen. The confined nature and the high evaporation of the Red sea contribute to the high salinity while the mining and transportation of phosphatic ore in the nearby region contribute to the high load of P and heavy metals. With the progress of season from September to November, water temperature was markedly reduced whereas pH and ionic content of water was reduced to a lesser extent, with marked alteration in ionic composition. With the progress of season towards winter, there was marked reduction in mineral composition of the fronds, shift in frond composition in favor of carbohydrates at the expense of proteins, lipids and alginates;and shift in the pigment composition in favor of chlorophylls at the expense of carotenoids and fucoxanthin.Conclusions: These facts point to active growth and photosynthetic activity during the cold period;that is, D. dichotoma is a cold water alga. D. dichotoma had moderate nutritive value, with moderate contents of carbohydrates, proteins, lipids and minerals. The mineral accumulation capacity of the fronds was more evident for N, P and K than for Ca, Mg and heavy metals.

Ecological and biochemical analyses of the brown alga Turbinaria ornata(Turner)J.Agardh from Red Sea coast,Egypt

Objective:To study ecological parameters and biochemical composition of brown seaweed,Turbinaria ornata(T.ornata)collected from Hurghada shores,Red Sea coast of Egypt during September,October and November,2015.Methods:T.ornata and its associated seaweeds were collected,identified and their abundances were estimated.Water of collection site was analyzed physicochemically as well as qualitative and quantitative analyses of phytoplankton.T.ornata was analyzed for protein,total carbohydrate,lipids,alginic acid,agar,pigments,minerals and heavy metals.Results:The results showed that macroalgal species recorded along Hurghada shores belong to Phaeophyta,Rhodophyta and Chlorophyta.At collection site,the moderate temperature,slight alkaline pH,low turbidity,high dissolved oxygen and valuable nutrient content of saline water exerted the massive growth of T.ornata with maximum abundance(24%)during October.The phytoplankton community was quite diverse with a maximum numbers of taxa(104.2×10^(8) cell/L)recorded during October.Analysis of T.ornata alga powder showed that high soluble carbohydrate(2.80±0.10 mg/g dry/weight)and chlorophyll c(0.0017±0.0001 mg/g fresh weight)contents were recorded during September;while high contents of protein(37.70±0.60 mg/g dry weight),lipids(3.10±0.06 mg/g dry weight),polysaccharides(agar and alginates),carotenoids(0.0160±0.0004 mg/g fresh weight),minerals and heavy metals were recorded during November.Conclusions:The study revealed that physicochemical analyses of water were varied slightly during the three months and suitable for the growth of T.ornata.It contains high amount of most biochemical constituents during October.

Evaluation of antibacterial activity of the brown Seaweed Turbinaria ornata(Turner)J.Agardh from Egypt

Objective:To investigate the potential antibacterial activities of ethanol extracts of Turbinaria ornata(T.ornata),Oleic acid(OA)and palmitic acid(PA)extracted from T.ornata as well as mixtures of OA and PA(1:1)against some bacterial species.Methods:Brown seaweed T.ornata was collected from Hurghada shores,Red Sea coast of Egypt.OA and PA were extracted from T.ornata.Ethanol extracts of T.ornata,OA,PA and mixtures of these two fatty acids(1:1)were tested for their antibacterial activities against Escherichia coli,Bacillus cereus,Bacillus subtilis,Klebsiella pneumonia and Staphylococcus aureus by the disc diffusion method.Results:Ethanol extracts of T.ornata,OA,PA and mixtures of OA and PA(1:1)showed antibacterial activities that increased significantly(least significant difference at 0.05 level)with increasing concentrations against all tested bacteria.Different concentrations of ethanol extracts of T.ornata and extracted OA showed its highest activity against Bacillus subtilis,while PA and mixtures of PA and OA(1:1)showed its highest activity against Bacillus cereus.The maximum inhibition activities were shown for mixtures of OA and PA(1:1).Scanning electron microscope showed that mixtures of OA and PA(1:1)caused plasmolysis and reduction in cell size of Escherichia coli.Conclusions:Different concentrations of T.ornata and its fatty acids showed activities against all tested bacteria.Therefore,it is a potential source of natural antimicrobial compounds.