Inka Dor

Separation and identification of hydrocarbons and other volatile compounds from cultured blue-green alga Nostoc sp. by gas chromatography–mass spectrometry using serially coupled capillary columns with consecutive nonpolar and semipolar stationary phases☆

The complex hydrocarbons and volatile compounds produced by cultured blue-green alga Nostoc sp. were separated by serially coupled capillary columns with consecutive nonpolar and semipolar stationary phases. More than 130 metabolites including, cyclohexane, cyclopentane, normal saturated hydrocarbons (C7-C30), fatty acids and benzene derivatives were identified by GC-MS. The most abundant family of hydrocarbons identified were derivatives of cyclohexane (41) and cyclopentane (11). Most of these compounds have not been reported previously in blue-green algae studies.

Carbon isotope variations in a solar pond microbial mat: Role of environmental gradients as steering variables☆

A biogeochemical traverse is presented for a juvenile benthic mat covering the depth profile of an artificially stratified and eutrophicated hypersaline heliothermal pond with known gradients of temperature, salinity, pH, and light transmission. It can be shown that visual mat development depends primarily on temperature and salinity as main environmental steering variables whose increase with depth goes along with the attenuation and final disappearance of a visible microbial film in the ponds hypolimnic compartment. Recorded biogeochemical parameters (Corg content, cell numbers, chlorophyll-a content) evidently reflect, as either biomass- or productivity-related index functions, the visually perceptible growth gradient of the microbial ecosystem along the pond slope. The observed coincidence of maxima in these index functions with maxima in δ13Corg clearly identifies high rates of primary productivity as the agent ultimately responsible for the generation of isotopically heavy (13C-enriched) biomass in these and related environments. Extreme demands placed on the local feeder pool of dissolved inorganic carbon by high rates of primary productivity entertained by the mat-forming microbenthos obviously give rise to severe CO2 limitation, enforcing the operation of a diffusion-(supply-)limited assimilatory pathway with an isotopically indiscriminate metabolization of the available CO2 resources.

Identification of oligosulfide odorous compounds and their source in the Lake of Galilee

Abstract The chemical source of objectionable odors that are emitted from the Lake of Galilee (Lake Kinneret) and the relationship to the lake algae were elucidated. The lake serves for recreation and as an operational water reservoir, supplying a quarter of the water consumption of Israel. Analysis by closed loop stripping apparatus (CLSA), coupled with GC/MSD, olfactory GC and other detectors, revealed that the odorous compounds belong to the methylsulfide family, including, dimethylsulfide, dimethyldisulfide, dimethyltrisulfide and methyl methanethiosulfonate. The odor episodes coincide with a bloom of Peridinium gatunense algae. Peridinium gatunense rich samples, taken from the lake during the bloom season, emitted the same sulfur compounds. Depth profiles of Peridinium algae, sulfur compounds, dissolved oxygen, pH and temperature revealed strong correlation between the algal photo-induced motion in the water column and the distribution of dimethyldisulfide and dimethyltrisulfide, while the concentrations of dimethylsulfide and methyl methanethiosulfonate did not follow the same trend. In all cases, the dimethyloligosulfides were produced in the oxic region and were independent of the anoxic conditions in the hypolimniumon or in the sediment.

Branched alkanes and other apolar compounds produced by the cyanobacterium Microcoleus vaginatus from the Negev desert

Gas chromatography–mass spectrometry on serially coupled capillary columns with different polarity of stationary phases showed that the soil cyanobacterium Microcoleusvaginatusfrom the Negev desert produces an unusual mixture of 4 normal and more than 60 branched alkanes, as well as a number of fatty acids, cyclic and unsaturated hydrocarbons, aldehydes, alcohols, and ketones. The dominant compounds were heptadecane (12%), 7-methylheptadecane (7.8%), hexadecanoic acid (6.5%), (Z)-9-hexadecenoic acid (5.6%), 4-ethyl-2,2,6,6-tetramethylheptane (2.8%), (Z)-9-octadecenoic acid (2.8%), and 4-methyl-5-propylnonane (2.7%).

Deep wastewater reservoirs in Israel: Empirical data for monitoring and control

Abstract Selected physico-chemical and biological variables were investigated in twelve reservoirs storing wastewater for irrigation. Organic load on the various reservoirs ranged from 1 to 15 kg BOD dunam −1∗ day −1 ; BOD of the reservoirs effluent ranged from 1 to 120 mg l −1 ; TSS from 6 to 150 mg l −1 ; chlorophyll a from 3 to 2700 μg l −1 : DO from 0.1 to 19 mg l −1 at midday; compensation levels from 0.2 to 3.5 m; and rates of respiration from 0.07 to 5 mg O 2 l −1 h −1 . Significant correlation coefficients obtained between the above variables prove that, despite their wide heterogeneity, these reservoirs constitute a well defined category of aquatic ecosystems, where a predictable behaviour is induced by increasing concentration of organic matter. The fact that water column transparency appeared significantly correlated with the concentration of BOD, TSS, chlorophyll and dissolved oxygen, predestinates underwater light measurements to serve as a useful parameter for a rapid assessment of reservoir water quality. Under the existing design, operation and local climatic conditions BOD levels of 40–50 mg l −1 appeared to be the upper limit for the safe performance of these reservoirs. In order to support such concentrations the organic load should not exceed 6 kg BOD dunam −1 day −1 . Reservoirs operated within the above limits store wastewater without causing nuisances and reduce the entering BOD by some 80%, which seems to be the maximal efficiency of these systems.

High density, dialysis culture of algae on sewage

Abstract Scenedesmus obliquus inoculated on tap water was grown in dialysis tubing suspended in raw sewage. Osmotic contact with the surrounding bacterial medium had a powerful stimulatory effect on algal growth. Algal biomass prolifered on the nutrients extracted from the waste water—without being mixed with it. The method seems to be promising for the production of single-cell algal protein from sewage.

Considerations about the composition of benthic algal flora in Lake Kinneret

Blue-green benthic algae are represented in Kinneret by numerous taxa but biomasses produced by them are inconspicuous. Diatoms, although less diversified show overwhelming biological activity.A comparative insight into the flora of the lake and the surrounding springs reveals many species in common, of which the diatoms develop the richest biomasses on the lake littoral, while the blue-greens reach their maximal biological success in the mineral and thermal springs.It is assumed that diatoms migrate from the lake to the surrounding springs, while the Cyanophyceae originating in the springs, move toward the lake.Climatic and hydrological changes, which had place throughout the geological history of the region, enhanced alternately one of the two algal groups competing for the lakes littoral, while limiting the other.Periods of high temperatures and salinities were favorable for the immigrants from the springs decreasing competitive capacity of diatoms; cold, rainy climates had opposite effect, enhancing diatoms but limiting growth of the thermophilic blue-greens on the lake shores.Vicinity of mineral and thermal springs creates constant “blue-green pressure” on the lake, which at present shows merely qualitative character but in suitable conditions may come to quantitative expression as well.

Photoprotection by Cichorium endivia Extracts: Prevention of UVB-Induced Erythema, Pyrimidine Dimer Formation and IL-6 Expression

In the gradual process of evolution, plants have developed natural sun protecting substances that enable continuous survival under direct and intense ultraviolet (UV) radiation. As part of our studies of plant-derived pigments that might constitute an alternative to conventional sunscreens, we have tested the ethanolic extracts of roots, stalks, and inflorescences of populations of wild Cichorium endivia subsp. divaricatum (Asteraceae) in terms of protection against sunburn, and in prevention of UVB-induced pyrimidine dimer formation and IL-6 mRNA expression in the human keratinocyte cell line, HaCaT. Using ELISA technique for detection of pyrimidine dimers and RT-PCR for detection of IL-6, we found that the ethanolic extract of C. endivia roots absorbs radiation in the UVB spectrum and partially prevents induction of pyrimidine dimers and IL-6 expression. Application of the root extract on the skin prior to UVB irradiation totally prevented erythema. Our findings suggest that C. endivia extracts might possess sun-protective qualities that make them useful as sunscreens.

Quantitative near-surface remote sensing of wastewater quality in oxidation ponds and reservoirs : a case study of the Naan system

This study develops a remote sensing technique for real-time monitoring of wastewater effluents stored before irrigation. Reflectance and attenuation coefficients for downwelling irradiance spectra (400 to 950 nm spectral resolution of 2 nm) were acquired simultaneously with turbidity, chlorophyll, organic matter, and total suspended matter concentrations in the Naan wastewater system, Israel. High-spectral-resolution spectrometric data were used to select the most suitable spectral bands for remote sensing of optically active constituent concentrations. Algorithms for remote estimation of wastewater quality expressed as chlorophyll-α, bacteriochlorophyll-α, and total suspended matter concentrations were developed. Reflectance height at 720 nm and an area above the base line from 670 to 950 nm was used in algorithms for chlorophyll-α assessment (r 2 > 0.83). For bacteriochlorophyll-α assessment, an area under the base line through 780 to 900 nm was used, allowing its quantitative estimation (r 2 > 0.94). Reflectance of approximately 570 and from 400 to 950 nm correlated closely with total suspended matter concentration (r 2 > 0.82) and was used to retrieve it from reflectance spectra. This is the first reported study on the quantitative remote assessment of wastewater quality. The results suggest that four spectral bands be used for real-time monitoring of wastewater ponds quality.

Experimental Hypersaline Ponds as Model Environments for Stromatolite Formation 2. Isotopic Biogeochemistry

The biogeochemical characteristics of a newly established microbial mat have been traced along the slope of an artificially stratified, eutrophicated hypersaline pond as a function of the principal environmental parameters. The sharp decline in both visual mat development and productivity index functions at the combined thermo-and haloclines shows productivity in the habitat to be primarily temperature-and salinity-dependent. Recordings of δ13Corg over the pond profile have identified high rates of primary productivity as the agent responsible for the generation of isotopically heavy bio-mass, negating the previously assumed role of salinity as a principal steering variable. Heavy demands placed on the local carbon dioxide pool by high productivity rates sustained by the mat-forming microbenthos obviously give rise to severe CO2-limitation and, consequently, to a largely indiscriminate metabolization of available CO2 supplies. The sizeable variations of δ 13Corg along the pond slope appear to be smoothed out in the corresponding δ13Ccarb functions, with only close scrutiny revealing a sympathetic relationship between the two parameters.