Low Molecular Weight Organic Compounds Research Articles

The First Information on the Low Molecular Metabolom Lobelia dortmanna (Campanulaceae, Magnoliophyta) Growing in the Northwest of the Russian Federation

The low molecular weight metabolome (LMWM) of Lobelia dortmanna L. (Campanulaceae, Magnoliophyta), a relic aquatic macrophyte listed in the Red Data Books of the Russian Federation and Republic of Belarus, was studied for the first time using the GC/MS technique. It is a macrophyte that grows in oligotrophic lakes in the northwest of the Vologda Region, Russia. Thirteen major chemicals were among the 127 volatile low molecular weight organic compounds (VOCs) discovered, which accounted for 77.23% of the overall VOC content (198.75 µg/g dry plant weight). The main components of LMWM were carboxylic acids and hydrocarbons. The presence of a large number of biologically active metabolites with a high concentration in L. dortmanna LMWM may indicate a significant effect of this plant on the hydrobiocenoses of the littoral zone of oligotrophic lakes. Further research into the LMWM of aquatic macrophytes in oligotrophic lakes, a valuable renewable resource, is needed to assess the background characteristics of the natural environment for more effective monitoring of the ecological state of water bodies in the Russian Federation's North-West and the rational use of their biological resources.

Composition of the Low Molecular Weight Metabolome of Potamogeton perfoliatus (Potamogetonaceae) as an Indicator of the Transformation of the Ecological State of the Littoral Zone

The composition and nature of changes in the low-molecular-weight metabolome (NM) of Potamogeton perfoliatus L., growing in 6 biotopes of Lake Ladoga with different types of the anthropogenic load has been analyzed. According to the research results, it was found that the total number of low molecular weight organic compounds (LMWOCs) in the P. perfoliatus NM composition is directly dependent on anthropogenic load, which is well marked by the development of cyanobacteria. The greater the intensity of pollution or eutrophication of waters, or the higher the number of cyanobacteria, the lower the total number of LMWOCs and their concentration. A strongly pronounced dependence of the total concentrations of groups of NM compounds on the anthropogenic disturbance of the biotope and the concentration of cyanobacteria was revealed. A decrease in the number, relative amount, total concentration of carboxylic acids, number and content of unsaturated fatty acids, and, at the same time, an increase in the composition and content of phenols and the total content of aldehydes and ketones depends on an increase in anthropogenic pressure. The specific composition of NM of pierced pondweed depends on its response to biotic and abiotic factors of the aquatic environment, including anthropogenic ones. The revealed features of the change in the composition of P. perfoliatus NM make it possible to use it as an integral indicator of the anthropogenic impact on the littoral biotopes of water bodies and the deterioration of their ecological state.

Fouling of Reverse Osmosis (RO) and Nanofiltration (NF) Membranes by Low Molecular Weight Organic Compounds (LMWOCs), Part 1: Fundamentals and Mechanism.

Reverse osmosis (RO) and nanofiltration (NF) are ubiquitous technologies in modern water treatment, finding applications across various sectors. However, the availability of high-quality water suitable for RO/NF feed is diminishing due to droughts caused by global warming, increasing demand, and water pollution. As concerns grow over the depletion of precious freshwater resources, a global movement is gaining momentum to utilize previously overlooked or challenging water sources, collectively known as "marginal water". Fouling is a serious concern when treating marginal water. In RO/NF, biofouling, organic and colloidal fouling, and scaling are particularly problematic. Of these, organic fouling, along with biofouling, has been considered difficult to manage. The major organic foulants studied are natural organic matter (NOM) for surface water and groundwater and effluent organic matter (EfOM) for municipal wastewater reuse. Polymeric substances such as sodium alginate, humic acid, and proteins have been used as model substances of EfOM. Fouling by low molecular weight organic compounds (LMWOCs) such as surfactants, phenolics, and plasticizers is known, but there have been few comprehensive reports. This review aims to shed light on fouling behavior by LMWOCs and its mechanism. LMWOC foulants reported so far are summarized, and the role of LMWOCs is also outlined for other polymeric membranes, e.g., UF, gas separation membranes, etc. Regarding the mechanism of fouling, it is explained that the fouling is caused by the strong interaction between LMWOC and the membrane, which causes the water permeation to be hindered by LMWOCs adsorbed on the membrane surface (surface fouling) and sorbed inside the membrane pores (internal fouling). Adsorption amounts and flow loss caused by the LMWOC fouling were well correlated with the octanol-water partition coefficient (log P). In part 2, countermeasures to solve this problem and applications using the LMWOCs will be outlined.

Small molecule communication of Legionella: the ins and outs of autoinducer and nitric oxide signaling.

SUMMARYLegionella pneumophila is a Gram-negative environmental bacterium, which survives in planktonic form, colonizes biofilms, and infects protozoa. Upon inhalation of Legionella-contaminated aerosols, the opportunistic pathogen replicates within and destroys alveolar macrophages, thereby causing a severe pneumonia termed Legionnaires' disease. Gram-negative bacteria employ low molecular weight organic compounds as well as the inorganic gas nitric oxide (NO) for cell-cell communication. L. pneumophila produces, secretes, and detects the α-hydroxyketone compound Legionella autoinducer-1 (LAI-1, 3-hydroxypentadecane-4-one). LAI-1 is secreted by L. pneumophila in outer membrane vesicles and not only promotes communication among bacteria but also triggers responses from eukaryotic cells. L. pneumophila detects NO through three different receptors, and signaling through the volatile molecule translates into fluctuations of the intracellular second messenger cyclic-di-guanylate monophosphate. The LAI-1 and NO signaling pathways are linked via the pleiotropic transcription factor LvbR. In this review, we summarize current knowledge about inter-bacterial and inter-kingdom signaling through LAI-1 and NO by Legionella species.

Soil organic matter priming: The pH effects.

Priming of soil organic matter (SOM) decomposition by microorganisms is a key phenomenon of global carbon (C) cycling. Soil pH is a main factor defining priming effects (PEs) because it (i) controls microbial community composition and activities, including enzyme activities, (ii) defines SOM stabilization and destabilization mechanisms, and (iii) regulates intensities of many biogeochemical processes. In this critical review, we focus on prerequisites and mechanisms of PE depending on pH and assess the global change consequences for PE. The highest PEs were common in soils with pH between 5.5 and 7.5, whereas low molecular weight organic compounds triggered PE mainly in slightly acidic soils. Positive PEs up to 20 times of SOM decomposition before C input were common at pH around 6.5. Negative PEs were common at soil pH below 4.5 or above 7 reflecting a suboptimal environment for microorganisms and specific SOM stabilization mechanisms at low and high pH. Short-term soil acidification (in rhizosphere, after fertilizer application) affects PE by: mineral-SOM complexation, SOM oxidation by iron reduction, enzymatic depolymerization, and pH-dependent changes in nutrient availability. Biological processes of microbial metabolism shift over the short-term, whereas long-term microbial community adaptations to slow acidification are common. The nitrogen fertilization induced soil acidification and land use intensification strongly decrease pH and thus boost the PE. Concluding, soil pH is one of the strongest but up to now disregarded factors of PE, defining SOM decomposition through short-term metabolic adaptation of microbial groups and long-term shift of microbial communities.

Seasonal distributions and possible sources of low molecular weight organic acids in PM2.5 from a typical mining city after decade green mining developing in Southeastern Hubei, Central China

Low molecular weight (LMW) organic compounds are prevalent in the atmospheric aerosols. Human activities and natural sources could significantly influence aerosol compositions and concentrations, particularly in a typical mining and metallurgy city. In this study, we measured dicarboxylic acids, ω-oxocarboxylic acids, pyruvic acid, α-dicarbonyls, and fatty acids in PM2.5 from Huangshi, China throughout one year. The results indicated that oxalic acid and glyoxylic acid were the most abundant dicarboxylic acid and ω-oxocarboxylic acid, respectively, across all seasons. Following nearly a decade of environmentally conscious economic development in Huangshi, it is observed that organic compounds primarily accumulated in PM2.5 due to the combustion of fossil fuels for mining-related activities and biogenic emissions. Furthermore, anthropogenic activities, including emissions related to traffic, biomass burning, and plastic incineration, significantly influence the composition of organic aerosols. Natural processes, such as atmospheric oxidation during long-distance transport, predominantly from North China, Mongolia, Russia, and Kazakhstan, also play a substantial role. The findings underscore the transitioning energy structures, modes of transport, and oxidation processes during long-distance transport have already begun to influence the composition of LMW organic compounds. The insights gained from this study offer valuable information for researchers and governmental authorities to understand the molecular composition and potential sources of LMW organic acids in the context of green mining development. This knowledge can aid in the formulation of targeted policies for the prevention and control of carbonaceous pollution in similar mining regions globally.

COMPARATIVE CHARACTERISTICS OF THE LOW MOLECULAR WEIGHT METABOLOME OF MACROPHYTES IN DIFFERENT WATER BODIES IN THE WATER AREA OF THE KANDALAKSHA BAY OF THE WHITE SEA

The Kandalaksha Bay of the White Sea underwent a first-of-its-kind comparative examination of the composition of essential oils of structure-forming macrophytes growing in freshwater and saltwater habitats. The essential oils of the aquatic macrophytes Nuphar lutea (L.) Sm., Ruppia maritima L., Zostera marina L., Fucus vesiculosus L., and Ascophyllum nodosum (L.) Le Jolis were obtained by steam hydrodistillation using the Clevenger apparatus from dried plants. Gas chromatography-mass spectrometry (GC/MS complex SHIMADZU GCMS-QP2010 Ultra) was used to analyze the qualitative and quantitative composition of LMWOCs (low molecular weight organic compounds). The component composition of the low molecular weight metabolome (LM) of macrophytes was shown to depend on both plant species specificity and plant habitat conditions (hydrological features, trophic state). More LMWOCs are found in plants from freshwater habitats than from marine ones. The investigated plants had only a few major compounds, ranging in number from 4 to 14. They accounted for between 70 and 83% of the overall concentration of all compounds in freshwater N. lutea and between 82 and 95% of the total concentration of LMWOCs in marine macrophytes. The most significant (% of the total essential oil) main components in macrophytes were carboxylic acids, specifically hexadecanoic, tetradecanoic, linoleic, and linolenic. The outcomes gained proved that the presence of carboxylic acids is a sign of a healthy macrophyte environment. The composition of LM of plants from northern habitats (marine and freshwater) contains high total concentrations of LMWOCs (including valuable ones from the perspective of economic use), making it possible to consider them as a valuable natural renewable resource for obtaining raw materials for various economic uses.

Microbial hub signaling compounds: natural products disproportionally shape microbiome composition and structure

Abstract Microbiomes are shaped by abiotic factors like nutrients, oxygen availability, pH, temperature, and so on, but also by biotic factors including low molecular weight organic compounds referred to as natural products (NPs). Based on genome analyses, millions of these compounds are predicted to exist in nature, some of them have found important applications e.g. as antibiotics. Based on recent data I propose a model that some of these compounds function as microbial hub signaling compounds, i.e. they have a higher hierarchical influence on microbiomes. These compounds have direct effects e.g. by inhibiting microorganisms and thereby exclude them from a microbiome (excluded). Some microorganisms do not respond at all (nonresponder), others respond by producing themselves NPs like a second wave of information molecules (message responder) influencing other microorganisms, but conceivably a more limited spectrum. Some microorganisms may respond to the hub compounds with their chemical modification (message modifiers). This way, the modified NPs may have themselves signaling function for a subset of microorganisms. Finally, it is also likely that NPs act as food source (C- and/or N-source) for microorganisms specialized on their degradation. As a consequence, such specialized microorganisms are selectively recruited to the microbiota.

Elucidation of biopotentiators in organic based formulation bijamrith from Gir Cow (Bos indicus) excrements and urine using GC-MS

Background: Traditional organic formulation bijamrith prepared from fresh urine and dung of cow is an important element in natural farming and extensively applied in modern agriculture practices to improve the soil fertility, control pest and disease in plants. The scientific validation of the biologically active compounds in bijamrith is unexplored. Methods: Bijamrith was prepared from excrements of Gir cow. Since, the volatile low molecular weight organic compounds from cow wastes could be derived from the solvent extract using GC-MS effectively, the compounds were separated by liquid-solvent extraction method using diethyl ether solvent and analyzed by GC-MS. Result: GC-MS analysis revealed the elution of about 40 different compounds in bijamrith formulation. Among them, fatty acid namely 9-octadecenoic acid (Z)-, an ester compound 2,3-dihydroxypropyl occupied higher concentration with peak area of 13.96% at 29.29 minutes of retention time which were reported to possess antifungal, antibacterial and anti-inflammatory activity. The other biologically active compounds eluted were antioxidants, plant growth hormones, nematicidal agents for defense mechanism and improvement of plant health.

Introduction to small molecule drug discovery and preclinical development

Over 90% of marketed drugs are small molecules, low molecular weight organic compounds that have been discovered, designed, and developed to prompt a specific biological process in the body. Examples include antibiotics (penicillin), analgesics (paracetamol) and synthetic hormones (corticosteroids). On average, it takes 10–15 years to develop a new medicine from initial discovery through to regulatory approval and the total cost is often in the billions. For every drug that makes it to the market, there are many more that do not, and it is the outlay associated with abortive efforts that accounts for most of this expense. The discovery of new drugs remains a significant challenge, involving teams of researchers from chemistry, biology, drug development, computer science and informatics. In this article we will discuss the key concepts and issues encountered in small molecule preclinical drug discovery and introduce some of the emerging technologies being developed to overcome current obstacles.

Gas Chromatography-Mass Spectrometric Study of Low-Molecular-Weight Exogenous Metabolites of Algae-Bacterial Communities in the Laboratory Accumulative Culture

The study of exogenous metabolites of algae-bacterial communities in the laboratory accumulative culture obtained from natural river water was conducted using gas chromatography-mass spectrometry. Exometabolites of the algae-bacterial community (including microalgae and cyanobacteria) in the culture medium were represented by saturated, unsaturated, and aromatic hydrocarbons, carboxylic acids, phenolic, and terpene compounds and their derivatives. Possible biological activities of the discovered exometabolites are considered. The study has demonstrated that an increase in the number of main groups of microorganisms, along with changes in the composition of algae and cyanobacteria, are responsible for the increase in the composition and concentration of metabolites in the microecosystem’s culture medium after one month of cultivation. The presence of octacosane in high concentration (0.0603 mg/L; 23.78% of the total content of low molecular weight organic compounds) by the end of exposure accumulative culture is associated with the strong development of the cyanobacterium Gloeocapsa sp. in the presence of diatom algae of the genus Navicula and green algae of the genera Chlorella and Scenedesmus. Due to the need to comprehend the ecological and biochemical mechanisms of the formation and functioning of algae-bacterial communities, as well as to predict potential paths of transformation and evolution of aquatic ecosystems, the specificity of exometabolite complexes of algae and microorganisms, as well as their allelopathic and other biochemical interactions in freshwater ecosystems, requires further serious study.

CHEMICAL COMPOSITION AND BIOLOGICAL PROPERTIES OF THE KIDNEYS OF POPULUS NIGRA L. OF THE CASPIAN REGION

The chemical composition of low molecular weight organic compounds (NOS) was studied by chromatography-mass spectrometric analysis of Populus nigra L. kidneys. Of the Caspian region and comparative antimicrobial (bactericidal) activity of extractive components with other plants with characteristic antimicrobial properties. The extraction was carried out by percolation in water-alcohol solutions. The study of antimicrobial activity was carried out by the standard CFU method. As a result, 49 compounds were identified, of which 10 remained unidentified. The study of comparative antimicrobial properties of plant extracts showed the complete bactericidal activity of Populus nigra kidneys against opportunistic microorganisms and microflora of air and water, in MIC equal to 0.25 micrograms/ml. Therefore, the NOSES isolated from the kidneys of Populus nigro of the Caspian region have prospects for further study of antioxidant activity for the preparation of biotechnological drugs and pharmaceutical substances.

In vivo polyamine applications to globe artichoke: Effects on plant growth-development and some bioactive components

The globe artichoke, Cynara cardunculus var. scolymus (L.), is an important member of the Asteraceae family, being used as a food and due to it has certain health-improving qualities in the treatment of various disorders since ancient times. Low molecular weight organic compounds with a role in several crucial cellular and physiological processes of plants are known as polyamines. They participate in processes such as cell division, differentiation, and growth, the sprouting of seeds, root formation, and flower and fruit development. They have been identified as particularly efficient against biotic and abiotic stress factors. The present research aimed that the evaluation of effects of various polyamine (PA) types and concentrations on three different artichoke cultivars by biometric measurements and biochemical analyses. For this purpose, seedlings of three artichoke cultivars (‘Sakız OP’, ‘Bayrampaşa OP’, and ‘Olympus F1’) were sprayed with various concentrations (0, 50, 100 and 250 mg L-1) of three distinct types of significant polyamines, including putrescine, spermidine, and spermine. Several growth parameters were examined in the current research. The effects on the total phenol and antioxidant capacities, as well as changes in the amounts of cynarin and 1,5-O-dicafeoylquinic acid, were also evaluated. The results revealed that there were statistically differences based on cultivars and treatment concentrations. Among the three forms of PA spermine was potent at increasing total phenolic content, while putrescine was effective at increasing total antioxidant content. On the other hand, putrescine, spermine and, spermidine had no positive effects on cynarin and 1,5-O-dicaffeoyquinic acid levels. Results clearly revealed that each biometric data and biochemical content could not be determined by a single polyamine type and concentration. It can be concluded that to improve the biometric values and biochemical content are depending on cultivar and dosage of various PAs.

Use of carbon-13 NMR to identify known natural products by querying a nuclear magnetic resonance database-An assessment.

The quick identification of known organic low molecular weight compounds, also known as structural dereplication, is a highly important task in the chemical profiling of natural resource extracts. To that end, a method that relies on carbon-13 nuclear magnetic resonance (NMR) spectroscopy, elaborated in earlier works of the author's research group, requires the availability of a dedicated database that establishes relationships between chemical structures, biological and chemical taxonomy, and spectroscopy. The construction of such a database, called acd_lotus, was reported earlier, and its usefulness was illustrated by only three examples. This article presents the results of structure searches carried out starting from 58 carbon-13 NMR data sets recorded on compounds selected in the metabolomics section of the biological magnetic resonance bank (BMRB). Two compound retrieval methods were employed. The first one involves searching in the acd_lotus database using commercial software. The second one operates through the freely accessible web interface of the nmrshiftdb2 database, which includes the compounds present in acd_lotus and many others. The two structural dereplication methods have proved to be efficient and can be used together in a complementary way.

Modeling the Migration Behavior of Extractables from Mono- and Multilayer Polyolefin Films to Mathematically Predict the Concentration of Leachable Impurities in Pharmaceutical Drug Products. Part 2: Conservative Diffusion and Partition Coefficient Determinations.

In the development of a pharmaceutical drug product packaging, an important step is to demonstrate acceptable levels of leachable impurities migrating from the packaging material into the drug product during its shelf life and therapeutic use. Such migration processes can be quantified either by analytical methods (which is often challenging and labor intensive) or (in many cases) through theoretical modeling, which is a reliable, quick, and cost-effective method to forecast the level of leachable impurities in the packaged drug when the diffusion and partition coefficients are known. In the previous part, it was shown how these parameters can be determined experimentally, and subsequent theoretical fitting of the results for a series of low- and high-molecular-weight organic compounds (known leachables) in a series of polyolefin materials was performed. One of the interpretations of these results is that a theoretical calculation can be made only for organic compounds and materials whose diffusion/partition/solubility coefficients were determined experimentally and theoretical fitting was achieved. However, in practice, there will be situations in which other leachable compounds may have to be investigated. In such cases, strictly speaking, it would be necessary to perform the whole experimental and fitting procedure for the new compound before a proper theoretical modeling is possible. But this would make the theoretical calculation of a leaching process from a pharmaceutical packaging material a cumbersome and cost intensive procedure. To address this problem, the pools of diffusion and partition coefficients were used to develop an approach that allows the estimation, without any additional experimentation, of so-called "conservative" diffusion and partition coefficients for a much wider range of potential leachables in the polyolefin pharmaceutical packaging materials and aqueous solutions investigated previously.

Emission characteristics and optical properties of brown carbon during combustion of pine at different ignition temperatures under high-time resolution

Biomass burning is a major contributor to atmospheric brown carbon (BrC). However, the properties of BrC from biomass burning can vary significantly based on combustion conditions and stages. To investigate these variations, we simulated the combustion cycle of pine at three different ignition temperatures (400, 600 and 800 °C) in a quartz tube furnace. Highly time-resolved samples were collected to analyze the emission and light-absorption properties of BrC during different combustion processes. Our findings revealed that the absorption emission factor at 370 nm was highest at 800 °C (14.96 ± 6.15 g·m−3) and lowest at 600 °C (3.48 ± 1.05 g·m−3). At lower combustion temperatures, we observed a higher content of low molecular weight organic compounds in BrC (OC1, OC2). Furthermore, the emission and light-absorption properties of BrC varied significantly throughout the combustion cycle, with clear bimodal distributions observed for OC, EC, and mass absorption efficiency at 365 nm at all three temperatures. The unimodal distribution of the absorption Ångström exponent indicated that highly aromatic BrC molecules were mainly produced at the beginning and end of the combustion events. We also found that low volatile OC components (OC3 + OC4) had a dominant effect on the variation in MAE365 at 400 and 600 °C, while high volatile OC components (OC1 + OC2) were more significant at 800 °C. These results suggest that the optical properties of BrC components can vary significantly depending on ignition temperature.

Bioutilization of the distillery stillage of different grain species from bioethanol production

Wastewater from bioethanol plants is classified as highly concentrated in terms of organic pollution precisely due to distillery stillage. The main problem in the disposal of distillery stillage is the processing of the liquid phase, the volume of which is up to 92% of all wastewater from a bioethanol plant. The existing wastewater treatment technologies of a bioethanol plant can be conditionally divided into four types: evaporation, aerobic biological treatment with fodder yeast production, anaerobic stillage treatment with biogas production, combined schemes. The aim of our work was to study a combined method for cleaning grain stillage by the anaerobic-aerobic method with the immobilization of microorganisms on a fibrous carrier. Physicochemical parameters of grain stillage and purified methane mash were determined according to generally accepted methods for analyzing wastewater from distilleries. Under anaerobic conditions, biogas was formed from distillery stillage, including low molecular weight organic compounds – methane, carbon dioxide, organic acids. After the first anaerobic stage of treatment, the pollution of wastewater decreased by 8-10 times, after which it was fed to the aerobic stage of post-treatment, which was carried out by microorganisms immobilized on a fixed carrier, which reduced the removal of biomass with the flow of purified water and improved treatment performance. The chemical oxygen demand (COD) of methane mash after the 1st stage of anaerobic fermentation was 1360 mg/dm3 compared to the initial COD of grain stillage of 15800 mg/dm3, which ensured a purification efficiency of 91.4%. The purification efficiency according to biochemical oxygen demand in five days (BOD5) was 97.5%. After the aerobic stage, the purification efficiency was 98.2% in terms of COD and 99.8% in terms of BOD5. The values of the content of total phosphorus also decreased by almost 20 times, nitrogen – by 9 times, sulfates – by 5 times. The advantages of the proposed method of wastewater treatment of bioethanol plants over existing ones are the ability to treat wastewater with any concentration of pollutants and additional obtaining of fuel – biogas, which can be used to replace natural gas, solving the problem of removing the biomass of microorganisms from the purification zone due to their fixation on a fibrous fixed carrier.

Visible light photocatalysis alleviates ceramic membrane fouling caused by intracellular organic matter of Microcystis aeruginosa

Ultrafiltration (UF) is an effective technology for treating algae-containing water. The algal intracellular organic matter (IOM) released by dead algae during an excessive algae growth phase causes more serious membrane fouling than viable algal cells and algal extracellular organic matter (EOM), which seriously restricts stable operation of UF. This paper studied the removal of IOM by a Bi2O3–TiO2/PAC (Bi-doped TiO2 nano-composites supported by powdered activated carbon) photocatalytic oxidation-ceramic ultrafiltration membrane, the inhibitory effect of membrane fouling at different photocatalytic oxidation times, and the fouling mechanism. The results show that both the adsorption and photocatalytic oxidation of Bi2O3–TiO2/PAC can significantly remove proteinoids and humic acid-like fluorescent components present in IOM, with removals of UV254 and DOC reaching up to 81.8% and 44.0%. The generated superoxide radicals and hydroxyl radicals positively affect the degradation of organic compounds of various molecular weights, and holes mainly degrade acidic low-molecular weight organic compounds. When the photocatalytic oxidation time was extended to 60 min, the membrane flux increased by 70.7% and the reversible resistance and irreversible resistance decreased by 83.4% and 90.1%, respectively. Under these conditions, the fouling mechanism changed from complete blockage to intermediate blockage. In the late stage of photocatalytic oxidation (90–120min), part of the high and medium molecular weight organic components were oxidized to produce low-molecular weight organic compounds (LMW acidic and neutral organic compounds), and blockage of filter cake became the main fouling mechanism. After photocatalysis, the zeta potential decreases significantly and the interaction forces between pollutants and pollutants are transformed into repulsive forces. Application of an appropriate photocatalytic oxidation time can alleviate the ultrafiltration membrane fouling caused by algal-derived organics.

Biological Activity and Composition of Metabolites of Potential Agricultural Application from <i>Streptomyces carpaticus</i> K-11 RCAM04697 (SCPM-O-B-9993)

Abstract—Strain K-11 was isolated from the highly saline brown semi-desert soil of the Astrakhan region. Based on analysis of the 16S rRNA gene sequence, this strain was identified as Streptomyces carpaticus K-11 RCAM04697 (SCPM-O-B-9993). Whole genome sequencing of the strain was performed. Phytotoxicity, antiviral, antioxidant, antifungal, and insecticidal activities of the strain were studied. All extracts and suspensions of S. carpaticus strain RCAM04697 had plant-stimulating activity. Antiviral properties was exhibited as suppression of development and propagation of viral pathogens in laboratory conditions: Tomato Mosaic Virus (ToMV) – 26.3%, Cucumber Mosaic Virus (CMV) – 33.8%, Y-Potato Virus (YVK) (Potato Y potyvirus, PVY) – 51.3%, Potato X-Virus (PVX) (Potato X potyvirus, PVX) – 41.3%. The highest antioxidant activity was shown by a suspension of S. carpaticus strain RCAM04697 (88.8%) and its aqueous-alcoholic (20 : 80) extract (76.0%). The strain inhibited growth of the phytopathogenic fungus Fusarium sporotrichioides to varying degrees. The insecticidal activity against Aphis fabae after 6 h of treatment was 100% in the variants with suspension treatment, water-alcohol (80 : 20, 50 : 50), methanol, and hexane extracts. The metabolites of the S. carpaticus RCAM04697 strain included flavonoids, alkaloids, glycosides, organic acids (isocitric, acetic, fumaric, lactic, pyruvic, and malic), alcohols, aldehydes, hydrocarbons, ethers, sulfur-containing compounds, and other groups of low-molecular weight organic compounds.

Solid phase extraction of ocean dissolved organic matter with PPL cartridges: efficiency and selectivity

Our current knowledge of the chemical composition of ocean dissolved organic matter (DOM) is limited, mainly because of its extreme molecular diversity, low concentration of individual compounds and the elevated ionic strength of ocean waters. As a result, many analytical methods require a previous extraction step. The efficiency and selectivity of the extraction method defines the representativeness of the extracted DOM fraction. Nowadays, the most widespread procedure for concentrating DOM is solid phase extraction (SPE) using styrene divinyl benzene polymer cartridges (PPL). Here, we investigate the effect of SPE-PPL on DOM elemental and optical properties to assess the efficiency and selectivity of this extraction method on water samples from the main intermediate and deep water masses of Arctic, Mediterranean and Antarctic origin present in the Cape Vert Frontal Zone (CVFZ, NW Africa). Furthermore, North and South Atlantic Central waters converge in this area and coastal DOM is injected by the giant upwelling filament of Cape Blanc. On one side, the colored fraction of DOM (CDOM) presented extraction efficiencies comparable to that of the bulk dissolved organic carbon (DOC), but decreased significantly with increasing wavelength, suggesting an affinity of PPL cartridges for low molecular weight organic compounds. While the protein-like fluorescent fraction of DOM (FDOM) was also extracted with the same efficiency than DOC, the extraction efficiency of the humic-like fraction was comparatively much higher. On the other side, dissolved organic nitrogen (DON) extraction efficiencies were about half that of DOC. These contrasting extraction efficiencies of the different DOM pools indicated that the extracts were enriched in N-poor, low molecular weight and recalcitrant DOM, therefore showing less variability than the corresponding bulk DOM. Furthermore, DOC, DON, CDOM and FDOM extracted were not homogeneous through the water column but displayed certain significant differences among water masses in both efficiency and selectivity.