Mostafa M. El-Sheekh

STABLE TRANSFORMATION OF THE INTACT CELLS OF CHLORELLA KESSLERI WITH HIGH VELOCITY MICROPROJECTILES

A transgenic expression system of Chlorella kessleri using the gene for β-glucuronidase (GUS) was developed. Cells of this unicellular green alga were bombarded with the plasmid pBI 121, which bears β-glucuronidase under the control of CaMV 35S promoter and the kanamycin resistant gene. Maximum GUS activity was obtained after 48 h of bombardment using a helium pressure of 900 kPa; GUS activity was then assayed for many generations. The stable transformants were able to grow on kanamycin containing medium after repeated passages between selective and nonselective medium and exhibited GUS activity comparable to that of control cells. Stable transformed cells were confirmed by polymerase chain reaction (PCR) and Southern hybridization of GUS probe with the genomic DNA of C. kessleri.

Growth and heavy metals removal efficiency of Nostoc muscorum and Anabaena subcylindrica in sewage and industrial wastewater effluents

The growth of Nostoc muscorum and Anabaena subcylindrica in sterilized sewage wastewater and N. muscorum in sterilized wastewater of El-Soda Company was higher than those grown in Allen synthetic medium. Whereas, the growth of A. subcylindrica in El-Soda Company sterilized wastewater and N. muscorum as well as A. subcylindrica grown in Verta Company sterilized wastewater was slightly lower than that grown in the standard synthetic medium. The contents of chlorophyll a, carotenoids and protein of N. muscorum and A. subcylindrica grown in sterilized sewage wastewater were higher than those grown in the standard medium. Similarly, N. muscorum and the bio-mixture of N. muscorum and A. subcylindrica grown in the sterilized wastewater of El-Soda Company showed high pigments and protein contents more than those reared in Allen medium. On the other hand, the bio-mixture of N. muscorum and A. subcylindrica grown in the sterilized sewage wastewater, A. subcylindrica grown in El-Soda Company and Verta Company sterilized wastewater showed lower contents of pigments and protein compared to synthetic medium. Heavy metals, copper, cobalt, lead and manganese were removed by 12.5-81.8, 11.8-33.7, 26.4-100 and 32.7-100%, respectively, from wastewater by using cyanobacterial cultures. The metal sorption efficiency depended on the type of biosorbent, the physiological state of the cells, availability of heavy metal, concentration of heavy metal and chemical composition of wastewater. It was observed also that the single cultures in most cases was better than the mixed cultures in heavy metal removal, this may be due to the cyanobacterial competition for nutrients in mixed cultures.

Effect of cobalt on growth, pigments and the photosynthetic electron transport in Monoraphidium minutum and Nitzchia perminuta

The unicellular green alga Monoraphidium minutum and the diatom Nitzschia perminuta were cultured under different concentrations of Co2+. Growth and pigment content were slightly increased at low concentrations and inhibited by high Co2+ concentrations. The results concerning the effect of different concentrations of Co2+ on photosynthetic O2 evolution showed a reduction in the amount of O2 evolved by each alga in response to increasing Co2+ concentrations. However, an increase in O2 evolution for both M. minutum and N. perminuta was observed at relatively low Co2+ concentrations. Photosynthetic electron transport in M. minutum was more sensitive to Co2+ toxicity than in N. perminuta. On the other hand, the effect of the heavy metal on respiration showed that higher Co2+ concentrations were inhibitory to O2 uptake by the two algal species. Low Co2+ concentrations stimulated O2 uptake by M. minutum throughout the experimental period. However, in N. perminuta, different concentrations of Co2+ led to a reduction of O2 uptake. To localize the action site of Co2+ in the photosynthetic electron transport chain, the fluorescence induction technique was carried out. According to the results obtained, the inhibitory action of Co2+ is located on the acceptor side of PSII for both M. minutum and N. perminuta.

Effect of atrazine herbicide on growth, photosynthesis, protein synthesis, and fatty acid composition in the unicellular green alga Chlorella kessleri

Sublethal atrazine concentrations induced a general inhibition on growth, photosynthesis, and dark respiration in the green alga Chlorella kessleri. 14C-protein hydrolysate indicated a maximum incorporation level by 5 microM atrazine after 48 hr. Progressive reduction in protein synthesis was associated with increasing herbicide concentration at all experimental periods. The herbicide had preferential effect on the associated fatty acid composition of total and phospholipids. After 24 and 48 hr the herbicide stimulated fatty acids synthesis at concentrations where photosynthesis was inhibited. Meanwhile, stearic and miristic acids disappeared at 15 microM after 24 hr and the total polyunsaturated fatty acids were not affected after 48 hr. Fatty acid synthesis was sensitive to treatment at 72 hr by 5 and 10 microM atrazine, whereas the total saturated fatty acids were completely inhibited.

Production and characterization of antimicrobial active substance from the cyanobacterium Nostoc muscorum.

In this investigation, the cyanobacterium Nostoc muscorum exhibited antagonistic activity against Gram-positive and Gram-negative bacteria and filamentous fungi. The results indicated that the active substance produced maximally after 12 days of incubation in shaken culture at 35°C, at pH 8.0 in BG-11 medium. The increase in nitrate concentration of the medium led to an increase in the antimicrobial production. Chloroform was the best solvent for extracting the active material. The antagonistic material was purified using thin layer chromatography. The compound showed maximum absorption at 240nm. Infrared (IR) and nuclear magnetic resonance (NMR) indicated presence of γOH, γCH aromatic, γCH aliphatic, γCN, γCO, γCC and CO. Mass spectroscopy indicated that its molecular weight is 279. The results also indicated that the compound is phenolic compound.

Differential effects of Co2+ and Ni2+ on protein metabolism in Scenedesmus obliquus and Nitzschia perminuta

Growth, morphological changes, amino acid composition, total soluble protein, and protein electrophoretic pattern were monitored for Scenedesmus obliquus and Nitzschia perminuta grown in the presence of different concentrations of Co(2+) and Ni(2+). Lower concentrations of cobalt stimulated the dry mass production and total soluble protein content of the two algae, whereas higher concentrations were inhibitory. Generally, N. perminuta showed more tolerance to the phytotoxicity of the two metals than S. obliquus and more tolerance to nickel than cobalt. However, S. obliquus seems to be more tolerant to cobalt than nickel. Cobalt and nickel have induced an increase in cell volume, change and disorder in cell shape. The increase in cell volume was much observed in Ni(2+) treated cells. At the same time, the two metals did not induce any distinct morphological abnormalities in N. perminuta. Co(2+) has stimulated the biosynthesis of all free amino acids in S. obliquus, except aspartic acid and phenylalanine, whereas Ni(2+) caused 22% inhibition in the content of total free amino acids, except cystine and arginine. On the other hand, Co(2+) has reduced the content of free amino acids in N. perminuta, except cystine, methionine, valine, and lysine. On the other hand, Ni(2+) stimulated the biosynthesis of glycine, alanine and histidine and highly stimulated valine and sulphur containing amino acids (cystine and methionine) in N. perminuta. High cobalt concentration (4ppm) resulted in the disappearance of 28.7kDa protein, 3.5ppm Ni(2+) stimulated the appearance of 18 and 20kDa proteins in S. Obliquus, while 37kDa proteins disappeared from N. perminuta treated with high doses of Co(2+) and Ni(2+).

Cytotoxic Activity of Biosynthesized Gold Nanoparticles with an Extract of the Red Seaweed Corallina officinalis on the MCF-7 Human Breast Cancer Cell Line

BACKGROUND Nano-biotechnology is recognized as offering revolutionary changes in the field of cancer therapy and biologically synthesized gold nanoparticles are known to have a wide range of medical applications. MATERIALS AND METHODS Gold nanoparticles (GNPs) were biosynthesized with an aqueous extract of the red alga Corallina officinalis, used as a reducing and stabilizing agent. GNPs were characterized using UV-Vis spectroscopy, transmission electron microscopy (TEM), energy dispersive analysis (EDX) and Fourier transform infra-red (FT-IR) spectroscopy and tested for cytotoxic activity against human breast cancer (MCF-7) cells cultured in Dulbeccos modified Eagle medium supplemented with 10% fetal bovine serum, considering their cytotoxicty and effects on cellular DNA. RESULTS The biosynthesized GNPs were 14.6 ± 1 nm in diameter. FT-IR analysis showed that the hydroxyl functional group from polyphenols and carbonyl group from proteins could assist in formation and stabilization. The GNPs showed potent cytotoxic activity against MCF-7 cells, causing necrosis at high concentrations while lower concentrations were without effect as indicated by DNA fragmentation assay. CONCLUSIONS The antitumor activity of the biosynthesized GNPs from the red alga Corallina officinalis against human breast cancer cells may be due to the cytotoxic effects of the gold nanoparticles and the polyphenolcontent of the algal extract.

Effect of two species of cyanobacteria as biofertilizers on some metabolic activities, growth, and yield of pea plant

Two cyanobacterial species (Nostoc entophytum and Oscillatoria angustissima) were tested as biofertilizers, substituting the normally used chemical fertilizer, for pea plant. Inoculation of soil with a suspension of each species or a combination of the two species significantly increased the germination percentage and stimulated the other measured growth parameters and photosynthetic pigment fractions of pea. However, the soil inoculation with one cyanobacterial species and the addition of the recommended dose or half the recommended dose of chemical fertilizer were usually more effective and also increased carbohydrate and protein contents of produced pea seeds. However, biofertilization combined with half the recommended dose of the chemical fertilizer was usually more effective than the addition of the full rate of the chemical fertilizer, and this may allow saving 50% of the used chemical fertilizer. The protein profile of the produced seeds showed appearance and disappearance of some protein bands in response to fertilization treatments compared to the control. Blue green algae analyses show that N. entophytum fixed more N, produced more exopolysaccharide, and contained more auxin and cytokinin than O. angustissima, the latter contained more gibberellins. These data may explain their different influences on growth and yield of pea.

Comparative studies on the green algae Chlorella homosphaera and Chlorella vulgaris with respect to oil pollution in the river Nile.

The effect of oil pollution on growth and metabolic activitiesof the fresh water algae Chlorella homosphaera and C.vulgaris was studied. The study was conducted on two locationsin the river Nile, one is oil polluted and the other is notpolluted. The assemblage of the different algal groups wasmonitored in both locations. Chlorophyta was more dominant thanCyanophyta and Bacillariophyta in both locations during allseasons except in winter when Bacillariophyta is the mostdominant group. The presence of crude oil or its refineryproducts (solar and lubricating) in the culture media of algaemarkedly influenced their growth, proteins and nucleic acidcontents. The toxicity of oil was a concentration dependent. Thelow concentrations stimulated growth, protein content andnucleic acids, whereas high concentrations had an inhibitoryeffect. Although DNA and RNA responded similarly to crude oil inthe two tested organisms, DNA showed more sensitivity than RNAto solar oil. Lubricating oil had a little phytotoxic effect onnucleic acids. Different species of algae response differentiallyto oil pollution; Chlorella vulgaris can be referred to asoil-sensitive, while Chlorella homosphaera can toleraterelatively higher concentrations of oil.

Cultivation of a new microalga, Micractinium reisseri, in municipal wastewater for nutrient removal, biomass, lipid, and fatty acid production

Coupling of advanced wastewater treatment with microalgae cultivation for low-cost lipid production was demonstrated in this study. The microalgal species Micractinium reisseri and Scenedesmus obliquus were isolated from municipal wastewater mixed with agricultural drainage. M. reisseri was selected based on the growth rate and cultivated in municipal wastewater (influent, secondary and tertiary effluents) which varied in nutrient concentration. M. reisseri showed an optimal specific growth rate (μopt) of 1.15, 1.04, and 1.01 1/day for the influent and the secondary and tertiary effluents, respectively. Secondary effluent supported the highest phosphorus removal (94%) and saturated fatty acid content (40%). The highest lipid content (40%), unsaturated fatty acid content, including monounsaturated and polyunsaturated fatty acids (66%), and nitrogen removal (80%) were observed for tertiary effluent. Fatty acids accumulating in the microalgal biomass (M. reisseri) were mainly composed of palmitic acid, oleic acid, linoleic acid, and a-linolenic acid. Cultivation of M. reisseri using municipal wastewater served a dual function of nutrient removal and biofuel feedstock generation.