Biogenic Surfactants Research Articles

Study on Surfactant-Polymer Flooding after Polymer Flooding in High-Permeability Heterogeneous Offshore Oilfields: A Case Study of Bohai S Oilfield.

Polymer flooding is an effective development technology to enhance oil recovery, and it has been widely used all over the world. However, after long-term polymer flooding, a large number of oilfields have experienced a sharp decline in reservoir development efficiency. High water cut wells, serious dispersion of residual oil distribution and complex reservoir conditions all bring great challenges to enhance oil recovery. In this study, the method of enhancing oil recovery after polymer flooding was studied by taking the S Oilfield as an example. A surfactant-polymer system suitable for high-permeability heterogeneous oilfields was developed, comprising biogenic surfactants and polymers. Microscopic displacement experiments were conducted using cast thin sections from the S Oilfield, and nuclear magnetic resonance was employed for core displacement experiments. Numerical simulation experiments were also conducted on the S Oilfield. The results show that the enhanced oil recovery mechanism of the surfactant-polymer system is to adjust the flow direction, expand the swept volume, emulsify crude oil and reduce interfacial tension. Surfactant-polymer flooding proves to be effective in improving recovery efficiency, significantly reducing the time of flooding and further enhancing the strong swept area. The nuclear magnetic resonance results indicate a high amplitude of passive utilization of residual oil during the surfactant-polymer flooding stage, highlighting the enormous potential for an increased recovery ratio. Surfactant-polymer flooding emerges as a more suitable technique to enhance oil recovery in the post polymer-flooding stage in high-permeability heterogeneous oilfields.

Effects of natural surfactants on the spatial variability of surface water temperature under intermittent light winds on Lake Geneva

The spatial variability of lake surface water temperature (LSWT) between smooth and rough surface areas and its potential association with the natural surfactant distribution in the surface microlayer were investigated for the first time in a lake. In spring 2019, two different field campaigns were carried out in Lake Geneva to measure: i) the enrichment factor of fluorescent dissolved organic matter (FDOM) as a proxy for biogenic surfactants, and ii) LSWT and near-surface water temperature profiles while simultaneously monitoring water surface roughness in both cases. Results indicate that, under intense incoming short-wave radiation and intermittent light wind conditions, the atmospheric boundary layer (ABL) was stable and the accumulation of heat due to short-wave radiation in near-surface waters was greater than heat losses by surface cooling, thus creating a diurnal warm layer with strong thermal stratification in the water near-surface layer. A threshold wind speed of 1.5 m s-1 was determined as a transition between different dynamic regimes. For winds just above 1.5 m s-1, the lake surface became patchy, and smooth surface areas (slicks) were more enriched with FDOM than rough areas (non-slick) covered with gravity-capillary waves (GCW). Sharp thermal boundaries appeared between smooth and rough areas. LSWT in smooth slicks was found to be more than 1.5°C warmer than in rough non-slick areas, which differs from previous observations in oceans that reported a slight temperature reduction inside slicks. Upon the formation of GCW in non-slick areas, the near-surface stratification was destroyed and the surface temperature was reduced. Furthermore, winds above 1.5 m s-1 continuously fragmented slicks causing a rapid spatial redistribution of LSWT patterns mainly aligned with the wind. For wind speeds below 1.5 m s‑1 the surface was smooth, no well-developed GCW were observed, LSWT differences were small, and strong near-surface stratification was established. These results contribute to the understanding and the quantification of air-water exchange processes, which are presently lacking for stable Atmospheric Boundary Layer conditions in lakes.

КОМБІНОВАНІ РОЗЧИНИ НЕРОЗЧИННИХ У ВОДІ БІОЛОГІЧНО АКТИВНИХ СПОЛУК З ВИКОРИСТАННЯМ БІОСУРФАКТАНТІВ

Solutions of biologically active substances insoluble in water (thiosulfoesters, anthraquinone derivatives, pyrazoline) were obtained using a combined solvent and biogenic surfactants. For this purpose were used rhamnolipids, their biocomplex with polysaccharides synthesized by the Pseudomonas SP strain. PS-17, trehalosolipids of the Rhodococcus erythropolis AU-1 strain, and the commercial biosurfactant surfactant. Aqueous dispersed systems of the studied substances were also obtained. The research results have prospects for use in pharmacy.

SURFACE WATER QUALITY IN KHARKIV RECREATIONAL AREAS: 2006-2020

The aim of the paper is to assess dynamics of water quality in four main recreational areas in Kharkiv and to develop recommendations for water quality improvement. Methods. Field and laboratory methods and analytical data processing. Results. The paper presents analysis of dynamics in water quality for four main recreational areas located in Kharkiv: Zhuravlevskiy Hydropark, Oleksiivskiy Lugopark, Udyanskiy Hydropark and Osnovyanske Lake. Period of study: 2006-2020, time: May-June and August-September. Average data are presented. Samples were analysed at certified Laboratory of Analytical Chemical Research of the Karazin Institute of Environmental Sciences. Laboratory data were compared with national UA standards and European ones. Conclusions were made for the following key parameters: dissolved oxygen and BOD5, total mineralization, biogenic substances content, oil products and surfactants, toxic heavy metals content. There is no specific dynamics on the pollution level. Conclusions. The following recommendations for improvement of water quality were developed: (i) to preform regular monitoring of water quality; (ii) to introduce regular and systematic control by one local authority; (iii) to improve infrastructure of recreational areas; (iv) to introduce regular cleaning of the recreational areas; (v) to install bio-WC; (vi) to install additional waste containers (preferably with separate waste collection); (vii) plant trees for better isolation from highways; (viii) to improve level of water treatment on WWTP; (ix) to create nature protected areas along rivers

Response and oil degradation activities of a northeast Atlantic bacterial community to biogenic and synthetic surfactants

BackgroundBiosurfactants are naturally derived products that play a similar role to synthetic dispersants in oil spill response but are easily biodegradable and less toxic. Using a combination of analytical chemistry, 16S rRNA amplicon sequencing and simulation-based approaches, this study investigated the microbial community dynamics, ecological drivers, functional diversity and robustness, and oil biodegradation potential of a northeast Atlantic marine microbial community to crude oil when exposed to rhamnolipid or synthetic dispersant Finasol OSR52.ResultsPsychrophilic Colwellia and Oleispira dominated the community in both the rhamnolipid and Finasol OSR52 treatments initially but later community structure across treatments diverged significantly: Rhodobacteraceae and Vibrio dominated the Finasol-amended treatment, whereas Colwellia, Oleispira, and later Cycloclasticus and Alcanivorax, dominated the rhamnolipid-amended treatment. Key aromatic hydrocarbon-degrading bacteria, like Cycloclasticus, was not observed in the Finasol treatment but it was abundant in the oil-only and rhamnolipid-amended treatments. Overall, Finasol had a significant negative impact on the community diversity, weakened the taxa-functional robustness of the community, and caused a stronger environmental filtering, more so than oil-only and rhamnolipid-amended oil treatments. Rhamnolipid-amended and oil-only treatments had the highest functional diversity, however, the overall oil biodegradation was greater in the Finasol treatment, but aromatic biodegradation was highest in the rhamnolipid treatment.ConclusionOverall, the natural marine microbial community in the northeast Atlantic responded differently to crude oil dispersed with either synthetic or biogenic surfactants over time, but oil degradation was more enhanced by the synthetic dispersant. Collectively, our results advance the understanding of how rhamnolipid biosurfactants and synthetic dispersant Finasol affect the natural marine microbial community in the FSC, supporting their potential application in oil spills.43fSDwbdHYX3Ei4X1BHK1YVideo abstract

Synthesis and antimicrobial activity of CuO nanoparticles stabilized by rhamnolipid biocomplex of microbial origin

A wide range of both physical and chemical methods has been developed for the synthesis of copper-based nanoparticles. At the same time, especially promising from the ecological point of view methods of obtaining colloidal solutions are the so-called “green” methods of synthesis, the essence of which is the use of natural biologically active substances and can also enhance the antimicrobial activity of the inorganic component. A promising class of polyfunctional substances can be considered biogenic surfactants (biosurfactants), namely the products of microbial synthesis, which are now widely studied and considered an environmentally friendly alternative to synthetic surfactants. Such biosurfactants often also have antimicrobial and antiviral activities, and therefore their combination with copper-based nanoparticles will combine and enhance the properties of both components to create modern environmentally friendly drugs with antimicrobial action. Among the wide range of promising microorganisms-producers of surfactants, the genus Pseudomonas deserves a special attention, which synthesizes extracellular surfactant glycolipids with high surface, emulsifying and foaming activities. Therefore, the aim of this work was to obtain concentrated colloidal solutions of copper oxide in the presence of a biogenic surfactant, so-called rhamnolipid biocomplex synthesized by culture of Pseudomonas sp. PS -17, which simultaneously provides satisfactory stabilization of colloidal copper solutions and is non-toxic, to study the effect of rhamnolipid biocomplex concentration on the characteristics of the obtained copper oxide nanoparticles, as well as to investigate their antimicrobial action. Concentrated colloidal solutions of copper oxide, stabilized by rhamnolipid biocomplex (RBC), which is a low molecular weight secondary metabolite of bacteria of the genus Pseudo ­ monas sp. PS -17 and at the same time provides satisfactory stabilization of colloidal solutions of copper oxide and is non-toxic have been synthesized. Copper oxide nanoparticles (CuO–NPs) were obtained by the decomposition reaction of freshly prepared copper hydroxide in an alkaline medium in the presence of RBC. The obtained CuO–NPs were investigated using scanning electron microscopy, spectroscopy in the UV-visible range, as well as the method of X-ray diffraction. It was found that the obtained CuO–NPs form agglomerates of irregular shape with a size of 35–90 nm. The sizes of crystallites of synthesized CuO–NPs were calculated by X-ray diffraction patterns. It was found that the size of the crystallites decreases from 12 to 5 nm with increasing initial concentration of RBC. The antimicrobial activity of the obtained concentrated sol against two test microorganisms, namely Agrobacterium tumefaciens and Xanthomonas campestris was studied. It was found that the obtained CuO–NPs show a sufficiently high antimicrobial activity against these microorganisms, and the values of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) are 20 and 40 μg/ml, respectively. Keywords: nanoparticles of copper oxides, green synthesis, antimicrobial activity.

Study of the State of Surface Waters of the Northeast Caspian Sea During Development of Oil Fields

The relevance of the research is due to the fact that the Kashagan field has resumed oil and gas production, and up to this date more than 40 million tons of oil have been produced. In this regard, the study of the state of pollution of surface waters and its dynamics is relevant. This article is aimed at detecting the state of contamination with biogenic elements, oil products, phenol, synthetic surfactants and heavy metals. The leading approach to the study of this problem is State Standard 17.1.5.04-81; The seawater sampling procedure is carried out in accordance with ISO 5667-9: 1992 and ISO 5667-2. The article presents the results of research conducted in 2019 and the dynamics of pollution with pollutants in the area of the Kashagan, Kairan and Aktoty fields in the licensed territory. At the Kashagan field, samples were taken from 14 observation stations for the study. The fields of Kairan and Aktoty are currently preserved. In this regard, 2 observation stations were studied at each of these deposits and the results were compared with the results of the previous year. Based on the data obtained, it was revealed that biogenic elements remained at the same level and below the maximum permissible concentration for the entire study period. Comparison with last years’ studies shows that in 2019, the concentration of biogenic elements was lower than 2018. The content of oil products and synthetic surfactants for the study period was higher than in 2018, but lower than the MPC for the fisheries reservoir, and the phenol content was at the level of 2018 and exceeds the maximum permissible concentration by 3 times. Heavy metals for the entire study period were at the same level, with the exception of copper and iron, the concentration of which is higher than in 2018, but less than the MPC. The materials of the article are of practical value for scientists engaged in the study of the state of the inland seas, undergraduates, doctoral students.

Improving the efficiency of phytoremediation technologies of oil-contaminated soils with the participation of natural sorbents-meliorants

Phytremediation is considered to be a promising and environmentally friendly way to restore oil-contaminated soils. However, the multicomponent nature of oil pollution, its low bioavailability, high stability, hydrophobicity, and toxicity require a comprehensive approach to its implementation. The purpose of the study is to investigate the influence of different types of sorbents-meliorants and their complexes with remediation agents on improvement of the efficiency of phytoremediation technologies of oil-contaminated soils. The study established that the most effective plants for phytoremediation of oil-contaminated soils are Vicia faba var. Minor, Pisum sativum L., Avena sativa L., which are the least exposed to toxic effects of oil among the studied crops, and better adapt to the conditions of oil-contaminated soils. The influence of sorbent-meliorants such as glauconite, zeolite, sawdust, and sunflower husk on the process of phytoremediation of oil-contaminated soils (oil content 5%) was studied. It was proven that sunflower husk is the most promising and available agent for accelerating phytoremediation. The study examined the individual and combined influence of mineral fertilisers, biogenic surfactants of microbial origin, and humates on the growth of Avena sativa plants under conditions of oil pollution, as well as on the process of soil restoration. The best results are obtained by application of the above agents in combination with sunflower husk. This complex (sunflower husk + mineral fertilizers + surfactants of microbial origin / humates) has a positive effect on Avena sativa plants – reduces the rate of oxidative stress, which indicates an improvement in the adaptability of plants to oil-contaminated soil; growth parameters increase; plant biomass accumulation; the total content of chlorophyll a+b increases; and there is an improvement in soil properties by reducing the oil content in soil, reducing phytotoxicity, increasing dehydrogenase activity

Evaluation of Anti-oxidant and Anti-biofilm Activities of Biogenic Surfactants Derived from Bacillus amyloliquefaciens and Pseudomonas aeruginosa.

Biosurfactants, the microbial originated surface active agents, can modify the physicochemical properties of surfaces and reduce the bacterial adhesion via changing bacterial adhesion interactions on surfaces. They were also able to block oxidative chain reactions and might show antioxidant properties. The goal of this study was to evaluate the antioxidant and antibiofilm activities of biosurfactants which were derived from two autochthonous biosurfactant-producing strains, Bacillus amyloliquefaciens NS6 (surfactin), and Pseudomonas aeruginosa MN1 (rhamnolipids). Their antioxidant activities were determined by ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) methods. Ferric thiocyanate (FTC) assay was used for determination of their lipid peroxidation inhibition capacity. Their effect to reduce the adhesion of Streptococcus mutans on polystyrene surfaces and disruption of its pre-formed biofilms were also investigated. Our results indicated that surfactin showed higher antioxidant activity than rhamnolipids and showed relatively similar efficiency to BHA that suggests it as a good alternative for synthetic antioxidants. In other hand, rhamnolipid conditioned surfaces showed higher antiadhesive and antibiofilm activity in comparison with surfactin treated surfaces.

Ecotoxicological assessment of synthetic and biogenic surfactants using freshwater cladoceran species

Surfactants have been continuously detected within aquatic environments as a consequence of their use on a global scale. Lipopeptides are biosurfactants naturally produced by Bacillus subtilis that have been explored as green alternatives. The assessment of ecotoxicological parameters of synthetic and biogenic surfactants are required for evaluating toxicity values and to verify the eco-friendly behaviour of the biological compounds. This study aimed to conduct toxicity testing for different surfactants – sodium dodecyl sulphate and Triton X-100 - and biosurfactants – surfactin, iturin and fengycin - at different concentrations using Daphnia magna as model organism and Dendrocephalus brasiliensis as alternative test species for monitoring of pollutants in tropical freshwaters. According results, both species showed high sensitivity for the anionic compound SDS concerning the recommended dosage use, exhibiting EC50–48h values of 24.1 and 15.4 mg/L for D. magna and D. brasiliensis, respectively. Although the biological source, surfactin showed the lower safety behaviour among the biogenic surfactants, while iturin and fengycin revealed very low toxicity effects on both organisms. Besides, data exhibited a higher responsiveness of D. brasiliensis for all tested compounds in comparison to D. magna, highlighting the importance of this species for monitoring of pollutants in tropical and subtropical environments.

Colloidal Characteristics of Water Systems of Rhamnolipid Biocomplex of Strain Pseudomonas Sp. Ps17 With Tween-80 and Their Prospects for Biotechnology

Background. Efficiency of mixed systems of biogenic and synthetic surfactants, based on their colloidal chemical properties, in environmentally safe technologies. Objective. The aim of the paper is the study of the aqueous systems’ colloidal characteristics of the rhamnolipid biocomplex with Twееn-80 nonionic surfactant, as well as the study of the obtained mixtures’ action for the emulsion stabilization and for plant growth stimulation. Methods. The surface tension of RBC, Tween-80, and their mixture solutions was measured by the Du-Nui method (with a platinum ring). The dependence of the surface tension on the surfactant concentration was determined for mixtures with RBC content, %: 0.0; 11.1; 25.0; 42.9; 66.7; 100. The emulsifying activity of the surfactant mixtures was determined on the emulsification index ( E 24 ). The surfactant influence on plants was assessed by their morphometric parameters after presowing seed treatment. Results. It was found that the obtained mixture behavior, regardless of the surfactant concentration, deviates from the ideal mixture – the deviation is negative, which indicates the predominance of RBC in the surface layer. The shapes of the surface tension curves for different surfactant ratios indicate synergistic effects before and after micelle formation. The optimum ratio in the RBC-Tween-80 system for sunflower growth and sunflower oil emulsification is 2:1. Conclusions. The peculiarities of colloid-chemical characteristics of RBC and Tween-80 systems are determined, the prospects of their use for increasing efficiency of emulsification and sunflower growth stimulation are determined.

Colloidal Characteristics of Water Systems of Rhamnolipid Biocomplex of Strain Pseudomonas sp. PS-17 with Tween-80 and their Prospects for Biotechnology

Background. Efficiency of mixed systems of biogenic and synthetic surfactants, based on their colloidal chemical properties, in environmentally safe technologies. Objective. The aim of the paper is the study of the aqueous systems’ colloidal characteristics of the rhamnolipid biocomplex with Twееn-80 nonionic surfactant, as well as the study of the obtained mixtures’ action for the emulsion stabilization and for plant growth stimulation. Methods. The surface tension of RBC, Tween-80, and their mixture solutions was measured by the Du-Nui method (with a platinum ring). The dependence of the surface tension on the surfactant concentration was determined for mixtures with RBC content, %: 0.0; 11.1; 25.0; 42.9; 66.7; 100. The emulsifying activity of the surfactant mixtures was determined on the emulsification index ( E 24 ). The surfactant influence on plants was assessed by their morphometric parameters after presowing seed treatment. Results. It was found that the obtained mixture behavior, regardless of the surfactant concentration, deviates from the ideal mixture – the deviation is negative, which indicates the predominance of RBC in the surface layer. The shapes of the surface tension curves for different surfactant ratios indicate synergistic effects before and after micelle formation. The optimum ratio in the RBC-Tween-80 system for sunflower growth and sunflower oil emulsification is 2:1. Conclusions. The peculiarities of colloid-chemical characteristics of RBC and Tween-80 systems are determined, the prospects of their use for increasing efficiency of emulsification and sunflower growth stimulation are determined.

Interfacial photochemistry of biogenic surfactants: a major source of abiotic volatile organic compounds

Films of biogenic compounds exposed to the atmosphere are ubiquitously found on the surfaces of cloud droplets, aerosol particles, buildings, plants, soils and the ocean. These air/water interfaces host countless amphiphilic compounds concentrated there with respect to in bulk water, leading to a unique chemical environment. Here, photochemical processes at the air/water interface of biofilm-containing solutions were studied, demonstrating abiotic VOC production from authentic biogenic surfactants under ambient conditions. Using a combination of online-APCI-HRMS and PTR-ToF-MS, unsaturated and functionalized VOCs were identified and quantified, giving emission fluxes comparable to previous field and laboratory observations. Interestingly, VOC fluxes increased with the decay of microbial cells in the samples, indicating that cell lysis due to cell death was the main source for surfactants and VOC production. In particular, irradiation of samples containing solely biofilm cells without matrix components exhibited the strongest VOC production upon irradiation. In agreement with previous studies, LC-MS measurements of the liquid phase suggested the presence of fatty acids and known photosensitizers, possibly inducing the observed VOC production via peroxy radical chemistry. Up to now, such VOC emissions were directly accounted to high biological activity in surface waters. However, the results obtained suggest that abiotic photochemistry can lead to similar emissions into the atmosphere, especially in less biologically-active regions. Furthermore, chamber experiments suggest that oxidation (O3/OH radicals) of the photochemically-produced VOCs leads to aerosol formation and growth, possibly affecting atmospheric chemistry and climate-related processes, such as cloud formation or the Earth's radiation budget.

Biogenic Rhamnolipid Surfactants in Complex Plant Growth Regulators

Biogenic Rhamnolipid Surfactants in Complex Plant Growth Regulators

Airborne radar imaging of subaqueous channel evolution in Wax Lake Delta, Louisiana, USA

AbstractShallow coastal regions are among the fastest evolving landscapes but are notoriously difficult to measure with high spatiotemporal resolution. Using Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) data, we demonstrate that high signal‐to‐noise L band synthetic aperture radar (SAR) can reveal subaqueous channel networks at the distal ends of river deltas. Using 27 UAVSAR images collected between 2009 and 2015 from the Wax Lake Delta in coastal Louisiana, USA, we show that under normal tidal conditions, planform geometry of the distributary channel network is frequently resolved in the UAVSAR images, including ~700 m of seaward network extension over 5 years for one channel. UAVSAR also reveals regions of subaerial and subaqueous vegetation, streaklines of biogenic surfactants, and what appear to be small distributary channels aliased by the survey grid, all illustrating the value of fine resolution, low noise, L band SAR for mapping the nearshore subaqueous delta channel network.

Використання біогенних поверхнево-активних речовин під час вирощування сорго насубстратах відвалів вугільних шахт

The influence of biogenic surfactants on the morphometric and oxidative characteristics of sorghum ( Sorghum bicolor subsp. drummondii ) during its growth on waste dump substrates of coal mines was investigated. It was found that presowing seed treatment with biosurfactants solutions – rhamnolipid biocomplex (RBC) or trehalose lipid surfactants (TL) – improved growth and oxidative parameters of plants, indicating the increase of sorghum resistance to adverse growing conditions. The best results were achieved when sorghum was grown on red substrate: shoots mass was increased in 2.20 times with RBC and in 1.19 times with TL, the root mass – in 2.30 and 1.71 times. Changes in antioxidant indicators of plants suggested the reducing of negative impact of unfavorable environmental factors of waste dumps. The content of malonicdialdehyde in sorghum on the red substrate was reduced by 15 % with RBC and 11% with TL and on the black substrate indicators were within the control levels. Рhenols content on the black substrate was increased in variants with RBC – by 141 % or with TL – by 184 % relatively to control. The content of H2O2 on the red substrate was reduced – by 11 % with RBC and by 10 % with TL, on the black substrate was within the control. The reducing of phytotoxicity of waste dumps of coal mines after sorghum growth (from highest to middle level) was shown. Obtained results showed the perspectives of application of sorghum and biosurfactants for the phytoremediation of the technogenic affected soils.

Застосування біогенних поверхнево-активних речовин для стабілізації фітопрепарату на основі безалкалоїдної фракції екстракту козлятника лікарського (Galega officinalis L.)

The article contains data on the influence of biogenic surfactants synthesized by bacteria Pseudomonas sp. PS-17 on the stability of emulsions based on alkaloid-free fraction isolated from Galega officinalis L. extract. The opti­mum concentrations of biogenic surfactants to stabilize investigated emulsionswere experimentally chosen. The chemical composition of alkaloid-free fractions from Galega officinalis L. extract before and after stabilization were investigated. The resulting substance is easier to administer to animals through a tube, which not only improves the accuracy of the dosage, but also increases its bioavailability. Reduction of glycosylated hemoglobin at 13.4 % and glucose content to the physiological values in the rats blood with experimental diabetes mellitus by administration within 14 days stabilized emulsions compared with the original emulsion shows that emulsion stabilized by the biogenic surfactant based on alkaloid-free fraction isolated from Galega officinalis an extract provides effective hyperglycemia compensation in rats under experimental diabetes mellitus, compared with the original mixture, which may be caused by changes in the proportion of biologically active substances in the extract while stabilizing and its better bioavailability.

Inhibiting Action of Biogenic Surfactants in Corrosive Media

It is shown that, for relatively low concentrations, the biogenic surfactants obtained as products of the biosynthesis of the Pseudomonas sp. PS-17 bacterial strain (culture supernatant and rhamnolipid biocomplex), are efficient corrosion inhibitors for D16T aluminum alloy in distilled water and in a 0.1% sodium chloride solution. Their efficiency increases their concentration. As soon as the critical micelle concentration is attained, any subsequent increase in the amount of biogenic surfactants in the corrosive medium does not affect the protective anticorrosion effect. The mechanism of corrosion inhibition is based on the adsorption of molecules of biosurfactants on the surface of aluminum alloy resulting in the formation of a barrier film. The rhamnolipid biocomplexes efficiently inhibit corrosion processes in heterogeneous aluminum alloys placed in chloride-containing media.

Light-enhanced primary marine aerosol production from biologically productive seawater

Physical and biogeochemical processes in seawater controlling primary marine aerosol (PMA) production and composition are poorly understood and associated with large uncertainties in estimated fluxes into the atmosphere. PMA production was investigated in the biologically productive NE Pacific Ocean and in biologically productive and oligotrophic regions of the NW Atlantic Ocean. Physicochemical properties of model PMA, produced by aeration of fresh seawater under controlled conditions, were quantified. Diel variability in model PMA mass and number fluxes was observed in biologically productive waters, increasing following sunrise and decreasing to predawn levels overnight. Such variability was not seen in oligotrophic waters. During daytime, surfactant scavenging by aeration in the aerosol generator without replenishing the seawater in the reservoir reduced the model PMA production in productive waters to nighttime levels but had no influence on production from oligotrophic waters. Results suggest bubble plume interactions with sunlight-mediated biogenic surfactants in productive seawater significantly enhanced model PMA production.

Вплив біогенних поверхнево-активних речовин і мікробного препарату на морфометричні показники проростків Raphanus sativus L. і Pisum arvense L.

It was determined that oilseed radish ( Raphanus sativus L.) and field pea ( Pisum arvense L.) are promising plants for phytoremediation of oil contaminated soils. The stimulating effect of the preparation based on oil-degrading microorganisms and biogenic surfactants (biosurfactants) on growth parameters of oilseed radish and field pea seedlings when grown in contaminated soils (2, 5 and 8% of crude oil) was determined. The greatest effect was detected for joint application of biosurfactants and microorganisms: the first stage – introduction of microbial preparation into the soil, second stage – planting of the seeds treated with biosurfactant solutions (rhamnolipid biocomplex PS or trehalose lipids). Such combined approach provides preliminary partial degradation of oil in soil by microorganisms, while biogenic surfactants can promote better assimilation of nutrients and water influencing the permeability of cell membranes of plants. It was shown that filed pea is more stable and perspective plant for cultivation on oil contaminated soil. The obtained results testify to the prospects of combined use of the preparation based on oil-degrading microorganisms and biogenic surfactants for enhancement of plant tolerance to adverse conditions such as petroleum contamination in soils. Keywords: microbial preparation, biogenic surfactants, rhamnolipid biocomplex, trehalose lipids, oil contamination, phytoremediation, oilseed radish, field pea.