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Microalgae have received continued attention as a potential source for biofuel production. However, the lack of suitable strains that provide a lipid-rich biomass and tolerate harsh condition inhibits their industrial application. This report describes an effort to transform Synechocystis sp. with genes encoding acetyl-CoA carboxylase (ACC), a key regulatory enzyme in the lipogenesis pathway, from the white mustard plant (Sinapis alba) and the bacterium Escherichia coli DH5α using chitosan nanoparticles. Although a recombinant plasmid encoding S. alba ACC failed to express, successful transformation was achieved with a recombinant plasmid encoding E. coli DH5α ACC. The successful transformant, Synechocystis sp. PAK13, exhibited increased ACC expression compared with its wild-type parent (11.8 vs. 7.2 ng), which significantly increased its lipid content (by 3.6-fold). Synechocystis sp. PAK13 also exhibited a significant (20%) reduction in photosynthetic pigments, a 1.52-fold higher glucose content and a 3.5-fold lower sucrose content than the wild-type. In conclusion, this report introduces a useful strategy to overexpress the ACC gene in microalgae, creating strains with improved lipid production that are suited to industrial applications.

Lung cancer is the primary cause of cancer-related death worldwide, and development of novel lung cancer preventive and therapeutic agents are urgently needed. Brassica nigra (black mustard) seeds are commonly consumed in several Asian and African countries. Mustard seeds previously exhibited significant anticancer activities against several cancer types. In the present study, we have investigated various cellular and molecular mechanisms of anticancer effects of an ethanolic extract of B. nigra seeds against A549 and H1299 human non-small cell lung cancer cell lines. B. nigra extract showed a substantial growth-inhibitory effect as it reduced the viability and clonogenic survival of A549 and H1299 cells in a concentration-dependent manner. B. nigra extract induced cellular apoptosis in a time- and concentration-dependent fashion as evidenced from increased caspase-3 activity. Furthermore, treatment of both A549 and H1299 cells with B. nigra extract alone or in combination with camptothecin induced DNA double-strand breaks as evidenced by upregulation of γH2A histone family member X, Fanconi anemia group D2 protein, Fanconi anemia group J protein, ataxia-telangiectesia mutated and Rad3-related protein. Based on cell cycle analysis, B. nigra extract significantly arrested A549 and H1299 cells at S and G2/M phases. Additionally, B. nigra extract suppressed the migratory and invasive properties of both cell lines, downregulated the expression of matrix metalloproteinase-2 (MMP2), MMP9, and Snail and upregulated the expression of E-cadherin at mRNA and protein levels. Taken together, these findings indicate that B. nigra seed extract may have an important anticancer potential against human lung cancer which could be mediated through simultaneous and differential regulation of proliferation, apoptosis, DNA damage, cell cycle, migration, and invasion.

THE CURRENT study investigates the effect of growth regulators on micropropagation, callus induction and callus flavonoid content of Rumex pictus Forssk; an endangered medicinal plant. Various combinations of kintin (KIN), 6-benzylaminopurine (BAP), Thidiazuron (TDZ) and indole-3-butyric acid (IBA) were used for micropropagation from shoot tip explants. Murashige and Skoog (MS) medium containing 2mg L-1 BAP was the best for micropropagation where shoot formation frequency was 70% with 12.6 shoots/explant. The highest root formation frequency resulted on half-strength MS medium fortified with 2mg L-1 naphthalene acetic acid (NAA) or 1mg L-1 IBA. One mg L-1 2,4-dichlorophenoxyacetic acid (2,4-D) combined with 0.4mg L-1 BAP induced the highest callus mass production from the investigated explants, particularly 1st foliage leaf that was the best explant for callus induction and proliferation. The accumulation of flavonoids in callus was diminished by BAP but enhanced by increasing 2,4-D concentration in culture medium. To our knowledge, this is the first report of micropropagation and callus induction of this endangered medicinal plant which will help in its rapid mass production, conservation and in vitro production of secondary metabolites.

Aims: Variation in the traditional growth medium conditions to enhance the production of lipids, carbohydrates, protein and the free amino acids content of three cyanobacterial species. Methodology and Results: Three species of cyanobacteria (Anabaena laxa, Anabaena fertilissima and Nostoc muscorum) were collected from the culture collection of Soils, Water and Environment Research Institute, Agriculture Research Center, Giza, Egypt, to investigate their biochemical composition under different growth conditions, using BG110 (nitrogen free) as growth medium. These conditions were represented by control medium, static glucose medium with (1%, w/v), aerated medium (aerated by bubbling technique depending on CO2 normally existed in air with a concentration of 0.03%), molasses medium (0.7%, v/v) and aerated medium enriched with glucose (1%, w/v). Lipid content, total carbohydrates, soluble proteins and free amino acids were determined at the previous conditions. Glucose at 0.7% (w/v) was the most favorable for lipid production in A. laxa, where it exhibited the highest lipid content (427 μg/g fresh wt.). Increasing molasses concentration up to 0.7% (v/v) produced an increase in lipid contents of the tested cyanobacterial strains. The highest lipid content of both N. muscorum (366.2 μg/g fresh wt.) and A. laxa (357.4 μg/g fresh wt.) were recorded at molasses concentrations of 0.1 and 0.7% (v/v), respectively. A. laxa expressed high significant values for both proteins (31.6 μg/mL) and free amino acids (40.5 mg/g dry wt.) after 6 days of incubation period under aerated enriched glucose condition (1%, w/v). Also, at the same growth conditions, A. fertilissima exhibited high significant values for carbohydrates at 4th day (876.8 mg/g dry wt.). Conclusion, significance and impact of study: Aerated enriched glucose medium (1%, w/v) was the best growth medium condition used in the present study.

From the active acetone fraction of Chenopodium murale, vanillic acid was isolated and identified, based on 1H and 13C nuclear magnetic resonance spectral analyses. Free phenolic compounds inside the active acetone were qualified and quantified by using high performance liquid chromatography analysis, which revealed the presence of seven compounds with an abundance of vanillic and p-hydroxybenzoic acids. The allelopathic potential of the acetone fraction and vanillic acid was evaluated through laboratory bioassays against tomato plants. Our results showed that the allelopathic potential induced by low concentrations of the acetone fraction and vanillic acid stimulated the germination and growth of tomato and had stimulating effects on the activity of some antioxidant enzymes. We observed an enhancement in the activity of catalase, peroxidase, superoxide dismutase, and polyphenol oxidase, as well as the content of soluble protein and phenolic glycoside. Meanwhile, the levels of free phenolic compounds, H2O2, and lipid peroxidation decreased. The highest stimulations were recorded at 50 p.p.m. of acetone fraction and 0.5 p.p.m. of vanillic acid. In contrast, the highest concentrations exerted negative effects on all the measured parameters to record the maximum value of inhibition at 400 p.p.m. of acetone fraction and 4 p.p.m. of vanillic acid. These results proved the antioxidative effects of active acetone and vanillic acid at low concentrations and their potent use as a stimulator for tomato germination and growth.

Abundance-occupancy relationships were determined for desert plants in the northwestern Red Sea region, at both the whole landscape, and individual habitat levels. Some 58 stands (having atotal of 66 species) were studied, using ten quadrats (10× 10m2) per stand. The relation was positive and highly significant at both scales, but stronger at habitat level than across the regional landscape. Niche-breadth was estimated as the number of habitats occupied regionally by a species, and was significantly related to both abundance and occupancy. Niche breadth explained just 10.1% of variation in abundance but some 56.2% of variation in occupancy. Using empirical data, we tested whether those abundance-occupancy relationships diverged significantly from a theoretical null model. Relationships diverged significantly from the null model at both regional landscape and habitat levels. Applications of abundance-occupancy relationships for plant conservation showed that 36% of the species in the study region is at risk of extinction.

The variations in the size, composition and diversity of the germinable soil seed bank were studied along an altitudinal gradient in the northwestern Red Sea region. The standing vegetation and the germinable seed bank were studied in 58 stands distributed along the altitudinal range from sea level to coastal mountain peaks. The classification of the germinable seed bank by the two-way indicator species analysis (TWINSPAN) led to the recognition of five groups representing different altitudinal ranges. Detrended correspondence analysis (DCA) shows that these groups are clearly distinguished by the first two DCA axes. The results demonstrate significant associations between the floristic composition of the seed bank and the edaphic factors such as CaCO 3 , electrical conductivity, organic carbon and soil texture. Species richness, Shannon index of diversity and the size of the germinable seed bank show a hump-shaped curve along the altitudinal gradient, whereas evenness shows a weak increase with elevation increasing. Beta diversity of the seed bank declines with altitude increasing. The similarity between the standing vegetation and the seed bank approaches a U-shaped pattern along the elevation gradient. About 34.8% of the species that constitute the standing vegetation are vulnerable to elimination from the standing vegetation because they are not represented in the seed bank. Soil seed bank can be used for restoration of the vegetation at some of the degraded sites.

Moringa peregrina (Forssk.) Fiori is a desert tree of economic and medicinal importance. Because of the severe drought and the over-exploitation of seeds and cutting of trees for firewood, the species is threatened. The survival, mortality and reproduction were studied for eight populations of M. peregrina distributed along the species altitudinal range (550–1000 m a.s.l.) in the northwestern sector of the Red Sea. Survivorship curves, life tables and fecundity schedules are constructed for the studied populations. Populations are dominated by adult individuals and the seedling recruitment is extremely limited. The survivorship curves approach Deevey type III in which the highest mortality occurs in the early life stages. The highest expectation for future life is exhibited by juveniles. The net reproductive rate ( R 0 ) ranges from 0.0023 to 0.0040. The intrinsic rate of increase per capita per year ( r ) varies between −0.121 and −0.081, suggesting that the populations are declining and their survival cannot be ensured without conservation measures. The plant density, seed output, average number of seeds per individual ( b x ), net reproductive rate ( R 0 ) and intrinsic rate of increase ( r ) of populations decrease significantly with elevation. The phenological development of M. peregrina is delayed with increasing altitude. The results indicated that the populations of M. peregrina in the northwestern sector of the Red Sea are threatened, in particular those located at the highest elevations of the species altitudinal range. Due to the very limited seedling recruitment, conservation efforts should be directed mainly to the established individuals. Efforts should be made to minimize the uncontrolled exploitation of the species by local people. In situ and ex situ conservation of Moringa populations are strongly recommended.

Two marine endophytic bacteria were isolated from the Red Sea algae; a red alga; Acanthophora dendroides and the brown alga Sargassum sabrepandum. The isolates were identified based on their 16SrRNA sequences as Bacterium SRCnm and Bacillus sp. JS. The objective of this study was to investigate the potential anti-microbial and antioxidant activities of the extracts of the isolated bacteria grown in different nutrient conditions. Compared to amoxicillin (25μg/disk) and erythromycin (15μg/disk), the extracts of Bacterium SRCn min media II, III, IV and V were potent inhibitors of the gram-positive bacterium Sarcina maxima even at low concentrations. Also, the multidrug resistant Staphylococcus aureus(MRSA) was more sensitive to the metabolites produced in medium (II) of the same endophyte than erythromycin (15μg/disk). A moderate activity of the Bacillus sp. JS extracts of media I and II was obtained against the same pathogen. The total compounds (500ug/ml) of both isolated endophytes showed moderate antioxidant activities (48.9% and 46.1%, respectively). LC/MS analysis of the bacterial extracts was carried out to investigate the likely natural products produced. Cyclo(D-cis-Hyp-L-Leu), dihydrosphingosine and 2-Amino-1,3-hexadecanediol were identified in the fermentation medium of Bacterium SRCnm, whereas cyclo (D-Pro-L-Tyr) and cyclo (L-Leu-L-Pro) were the suggested compounds of Bacillus sp. JS.

We assessed the allelopathic effects of the aqueous extract of Sonchus oleraceus dry shoots on the germination and seedling growth of Trifolium alexandrinum, three weed species (Brassica nigra, Chenopodium murale and Melilotus indicus) and S. oleraceus itself. We assayed four different concentrations of the aqueous extract (w v −1 ): 1%, 2%, 3% and 4%. To determine whether the effects of the extract were attributable to the presence of allelopathic compounds, its osmotic potential or both, we prepared concentrations of polyethylene glycol (PEG) with osmotic potentials equivalent to those of the aqueous extract. All concentrations of the plant extract completely inhibited the germination and seedling growth of C. murale. The lowest concentration of the plant extract partially inhibited germination and seedling growth of B. nigra, M. indicus and S. oleraceus, whereas the higher concentrations inhibited those parameters completely. The germination of T. alexandrinum was not affected by the aqueous extract at 1% or 2%. In general, the aqueous extracts were more effective in inhibiting seed germination and seedling growth than were the PEG solutions. Phytochemical analyses revealed that phenols and alkaloids were the most abundant compounds in S. oleraceus dry matter. Our results suggest that the aqueous extract of S. oleraceus has an allelopathic effect on some weeds, and its usefulness as a bioherbicide therefore merits further study.

Synechococcus has the ability to grow at temperatures lower than their normal growth temperature, although at a relatively reduced rate. Gel electrophoretic analysis of cellular proteins from cold — treated and heat shocked cells labeled with 14 C-protein hydrolysate revealed differences in the pattern of protein synthesis. The molecular weights of polypeptides induced at low temperatures (10 – 22 °C) were estimated to be 74, 64.5, 23, 17 and 14.7 kDa. Time course studies indicated progressive induction of some cold shock proteins (CSPs) at 13 °C. Heat shock (HS) involved immediate repression of most non heat shock proteins and identification of newly synthesized protein bands with molecular weights estimated to fall into the range characteristic for HS. The results revealed that in Synechococcus the photosynthetic activity and the midpoint value for critical temperature regions are dependent on growth temperature. The reduction in O 2 — evolution ranged between 37% to 47% within the studied low temperature range. Treatment at 10 and 13 °C showed rapid loss of activity (50%) after 17 and 29 min, respectively. Furthermore, treatment at 13 °C produced a change in light absorption spectrum A pattern which indicated the involvement of a common mechanism in the cold susceptibility of photosynthesis and absorption spectrum. It is suggested that cold induced particle movement which lead to functional detachment of phycobilisomes away from the Chl-protein complex or vice versa.

The performance of microalgae aquaculture wastewater treatment system predominated mainly by Scenedesmus and Chlorella was assessed. Treatment induced a progressive reduction in both COD and BOD to values below the discharge limits. Different patterns were obtained for removal of phosphorus, nitrogen, and ammonia; however, the algal culture efficiencies reached 100% in their removal by the end of the treatment period. The applied aquatic systems demonstrated percentage reduction of heavy metals in the range between 52.3 and 100% in the batch system and 64.2 and 100% in the continuous system. Wastewater supported algal growth by inducing the incorporation of a significantly higher content of the individual amino acids Asp, Thr, Ser, Glu, Gly, and Tyr, and a markedly higher level of Pro. However, His, Lys, and Arg were markedly reduced compared to their levels in synthetic-medium-grown algae.

Lemna gibba grown on mixtures of Nile-to-wastewater ratio of 1:1 (C) and 1:3 (D) exhibited maximum gain in fresh and dry weights. The Lemna system was capable of efficient quantitative and qualitative algal reduction. Maximum efficiency in algal removal was achieved in mixture “C” (94.4%). The ammonia rate of reduction was markedly high in mixtures enriched with wastewater with a complete depletion of any detectable nitrogen. The protein content in Lemna tissue increased upon enrichment with wastewater, and reached a maximum of 47.1% in mixture “D,” with a maximum increase in all amino acids. Lys content markedly increased by 105%. The treatment showed a maximum reduction in Fe and Zn in water mixture “D,” which correlated with their maximum bioaccumulation level in L. gibba tissue. Lemna gibba performed 100% efficient Mn removal after 16 days in all treated mixtures with minimum accumulation in the tissue.

An alkaliphilic actinomycete strain, designated YIM 80379T, was isolated from a soil sample collected from the eastern desert of Egypt and subjected to polyphasic taxonomy. The strain produced substrate and aerial mycelia on different media, with an optimum pH for growth of 9·5–10 and scarce or no growth at pH 7. Strain YIM 80379Tcontainedmeso-diaminopimelic acid, no diagnostic sugars, type PIII phospholipids and MK-10(H6) and MK-10(H8) as the predominant menaquinones. All of these characters assign isolate YIM 80379Tconsistently to the genusNocardiopsis. This was confirmed by 16S rDNA analysis. It can be differentiated from allNocardiopsisspecies with validly published names by phenotypic characteristics, phylogenetic analysis and DNA–DNA hybridization results. On the basis of polyphasic evidence, a novel species,Nocardiopsis alkaliphilasp. nov., is proposed. The type strain of the species is YIM 80379T(=CCTCC AA001031T=DSM 44657T).

Assessment of the influence of carbofuran on the nontarget cyanobacterium Anabaena doliolum revealed that this sheathless heterocystous form of cyanobacteria was more sensitive to the insecticide carbofuran. Anabaena doliolum was initially able to utilize low concentrations of carbofuran, whereas higher concentrations and the subsequent formation of hydrolytic breakdown products were toxic. Growth inhibition reached more than 50% by treatment with 80 and 100 ppm of the insecticide. Nitrogenase activity of the cyanobacterium was reduced by 38% after 48 h by treatment with 100 ppm carbofuran with no observed change in heterocyst frequency. Toxicity of the insecticide was the highest at pH 4-6 (46-59%) and the lowest at pH 7-10 (12-27%) due to the persistence of carbofuran and the resulting alkaline-catalyzed hydrolysis associated with the water regime of the rice fields. Doubling the initial population level of the cyanobacterium reduced the toxicity of the insecticide.

Aim This study is an attempt to explore the biological activities of isolated endophytic bacteria from marine sources that were coded A1, A2, and A3 (Padina pavonica), A4 (Cystoseira myrica), A5 (Acanthophora dendroides), and A6 (Sargassum sabrepandum). The bacteria coded C1, C2, and C3 were isolated from the soft coral Nephthea mollis and S1 and S2 were isolates from the sponge Hymedesmia spp. The primary aim of the study was the identification of active compounds. Materials and methods The bioactive compounds were extracted using ethyl acetate from nutrient broth media; biological activities of the extracted metabolites and 16S rDNA identification of the most promising isolate were studied. The eight major fractions of the extract showed different composition patterns when identified by liquid chromatography/mass spectrometry analyses. Results and conclusion Agar diffusion assay showed inhibitory activities of A4 extracts against the growth of most pathogenic microorganisms. Identification using PCR 16S rDNA and electrophoresis confirmed 98% identity to the Enterobacter cloacae strain GH1 (ac: JF261136.1). Eight compounds out of fifteen in the extract were identified as diketopiperazine derivatives. The maximum growth of E. cloacae was obtained at 30°C, pH 7, with the addition of maltose and KI to the media. The free radical scavenging activity exhibited good antioxidant activity (72.19%, IC 50 = 1.266 mg/ml) on using 2.0 mg/ml of the crude extract. The extract showed a high antiviral activity towards Newcastle disease virus and avian influenza virus A(H5N1).

The response to the extract of the Egyptian wild herb Calendula micrantha, with molluscicidal activity, was examined in the unicellular cyanobacterium Synechococcus sp. strain PCC 6301. Growth and chlorophyll a of the cells were only slightly affected by low concentrations but drastically reduced by high concentrations. The rate of protein synthesis progressively decreased by increasing extract concentration. The cells preferentially induced the synthesis of a limited number of polypeptides in response to the treatment. Among the induced polypeptides were those with apparent molecular weights of 161K (161,000), 96.7K, 93.4K, 85K, 69.9K, 59K, 49K, 45K, 35K, 32.4K, 28K, 24K, 21.7K, 18K, and 16K based on their mobilities in gel electrophoresis. These initial studies suggest that the plant extract exerted certain stress which stimulated alteration in the pattern of protein synthesis in Synechococcus sp. Some of the induced polypeptides are similar to that known to occur in other stresses, especially heat-shock stress.

The cyanobacteriumSynechocystis PCC 6803 was grown photoautotrophically in an inorganic medium at constant growth temperatures of 20, 38 (control) or 43°C for 9 h. The up and down-shift of cultivation temperature decreased the growth as measured by culture absorbance and chlorophylla content. However, high temperature slightly increased the oxygen evolution while temperature lower than control inhibited oxygen evolution during the whole incubation period. The protein synthesis studied by14C-labeled protein declined under low temperature by about 50%. The fatty acid pattern is characterized as lacking in C20/C22 acids but containing large amounts of C16 and C18 polyunsaturated fatty acids, 16:2 and 18:3 in particular. The lower temperature increased the percentage of monounsaturated fatty acids while higher temperature increased the saturated fatty acid content in total lipids and lipid classes studied.

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.

Calendula micrantha water extract was added to cultures of the green alga Chlorella kessleri and cyanobacterium Synechocystis PCC 6803. Treatments enhanced growth of the cultures, increased chlorophyll content, and 14C-labeled protein synthesis. However, a general induced protein synthesis pattern by 0.5% extract was observed reaching maximum level after 24 and 36 h in Chlorella and Synechocystis, respectively. Oxygen evolution in Chlorella was markedly inhibited after 12 h and slightly inhibited at longer exposure times and accompanied by a two- to fourfold increase in respiration at all experimental periods. Extracts induced oxygen evolution after 48 h in Synechocystis reaching maximum (52%) at 0.5%. The cyanobacterium exhibited a general reduced respiration pattern after 24 h which slightly increased afterwards. Calendula extract at 0.7% after 12 h had a preferential effect on both unicultures, as in Chlorella it markedly reduced protein synthesis and the oxygen evolution was minimum, whereas in Synechocystis it slightly reduced the level of protein synthesis with increasing oxygen evolution. The preferential effect was exhibited by all extract concentrations after 48 h, where protein synthesis was moderately induced in Chlorella and markedly inhibited in Synechocystis.

The isolation and characterization of cyanogen bromide peptides derived from the human gingival collagen of patients with chronic periodontitis revealed the presence of both Type I and Type III collagens in this tissue. The amount of Type III collagen, however, was found to be lower than that in normal gingival tissue. In addition, a non-collagenous protein fraction, accounting for approximately 20% of the insoluble matrix, was relatively rich in acidic, hydrophobic, and hydroxy-containing amino acids. Amino acid analysis, likewise, revealed qualitative and quantitative differences between the normal and diseased tissues.

Interference of Sonchus oleraceus was studied by evaluating its competitive and allelopathic potential on three weed species: Brassica nigra , Chenopodium murale and Melilotus indicus . The allelopathic potential of S . oleraceus was assessed using the S . oleraceus -infested soil collected from its dominating communities and its root exudates trapped using living S . oleraceus , while its competitive ability was assessed in greenhouse in an additive design with ratio 1:1 at different densities. The rhizosphere soil of S . oleraceus inhibited germination and growth of B . nigra and M . indicus . Chlorophyll content of the target weeds was not affected in this test. Soils containing living S . oleraceus inhibited germination and growth of all weeds except germination of C . murale . Interspecific competition reduced germination of C . murale and M . indicus , and increased mortality of the former at all densities. HPLC analyses for soil samples indicated the presence of several phenolic compounds among which caffeic acid and catechol were abundant in the S . oleraceus -infested soil while caffeic and ferulic acids were abundant in its root exudates. The data suggest that both allelopathic and competitive potential of S . oleraceus function, and its interference plays at least a partial role in the community organization of weeds in agroecosystem.

Limited proteolysis with pepsin solubilized 25% of the insoluble gingival matrix as mainly soluble collagenous material. Fractional salt precipitation at neutral pH resulted in the separation of types III and I at 1.8 and 2.6 M NaCl, respectively. In addition, a collagenous fraction accounting for 2% of the solubilized collagen and precipitating at 4.5 M NaCl was shown to be identical with type V collagen. Isolation and partial characterization of the constituent-alpha-chains of the 4.5 M PPT by gel filtration, ion exchange and hydroxylapatite chromatography as well as disc electrophoresis showed that gingival type V collagen contains alpha A and alpha B chains in a ratio alpha B/alpha A of 1.73-1.8. Electron microscopic examination of ATP-precipitates showed that this collagen type gave only one kind of SLS aggregates with asymmetric band pattern characteristically different from that of type I collagen. The data provide evidence that gingival AB collagen is a heteropolymer in which the alpha A and alpha B chains are assembled in the same macromolecule in a 1:2 ratio.

The taxonomic position of an actinomycete isolated from a soil sample collected from Wadi Sannur in Egypt was established using a polyphasic approach. The isolate, which was designated WS 51T, was shown to have chemical and morphological properties typical of streptomycetes. An almost complete 16S rDNAgene sequence of the strain was generated and compared with corresponding sequences of representative streptomycetes. The resultant data confirmed the classification of the strain in the genusStreptomyces but also showed that it formed a distinct phyletic line within the 16S rDNAStreptomyces gene tree. The organism was most closely associated to the type strains of Streptomyces hygroscopicus, Streptomyces malaysiensis and Streptomyces yatensis but was readily separated from them using a range of phenotypic properties. It is proposed that strain WS 51T (= CCTCC 001032T = DSM 41834T) be classified in the genus Streptomyces as Streptomyces sannurensis sp. nov. Key words: Streptomyces sannurensis sp. nov., polyphasic taxonomy, alkaliphilic streptomycete.