Microbiological Transformation Research Articles

Evaluation of biocorrosion, biofouling, and health risks in the two study locations in danube alluvium

Within conducted research the results of microbiological investigations on specific metabolic (phenotypic) groups of bacteria that play crucial roles in the biogeochemical cycling of iron, manganese, nitrogen, sulfur, and carbon are presented. These bacteria are also involved in the development of biocorrosion and biofouling processes, with some posing risks to public health. Utilizing results from applied biological activity reaction tests (BART tests), processed using specialized software, potential risks for the development of microbiologically mediated corrosion, biofouling, and health risks were calculated for seven wells within two oxic sites in the Danube alluvium – Vinci and Veliko Gradište, Serbia. Moderate to high corrosion risk was determined for all seven wells at both sites (CR=5.4). Microbiological fouling risk was very high in three out of the seven investigated wells (PR=8.10). Among the seven sites studied, one site stood out based on the calculated high value of health risk coefficient (HR=8.10). The research results provide new insights into the microbiological role in aging wells in oxic groundwater of the Danube alluvium. It is demonstrated that the physicochemical composition and chemical species such as minerals, organic matter, and the specific composition of microbial communities in the studied groundwater have the potential to stimulate biocorrosion and the formation of deposits and biofilms within well structures. In addition to biochemical analyses, hydrogeological characteristics of the analyzed area are presented to define the geological stratigraphy, for which specific microbiological transformations would be expected based on the obtained results.

Impacts of Humic Acid on Growth and Yield of Wheat: A Review

Wheat (Triticum aestivum L.) is a crucial crop, providing 20% of caloric intake for many populations worldwide. Soil organic matter, an essential component of soil, directly influences soil fertility and texture. Humic substances, derived from biomolecules' physical, chemical, and microbiological transformation, are integral to soil humus. Humic acid has become a standard method for enhancing crop growth, yield, and soil fertility. While the effects of humic acid on wheat have been extensively studied, the optimal type and application method for wheat cultivation remain undetermined. This review investigates sustainable wheat production methods using humic acid to mitigate the negative impacts of chemical fertilizers and climate change factors. Research indicates that humic acid significantly increases wheat plant growth parameters: shoot length (18%), root length (29%), shoot dry weight (76%), root dry weight (100%), and chlorophyll content (96%). Moreover, humic acid substantially improves wheat yield and yield components, including spike length (14.66%), number of spikes per square meter (28.73%), number of spikelets per spike (23.52%), and 1000-grain weight (23.90%). As a sustainable organic substance, humic acid application offers a promising approach to improving wheat production. This method could help meet the food demands of the growing global population, particularly in countries like Afghanistan, where food security is a pressing concern.

Procedure for rapid determination of bile-tolerant gram-negative bacteria in drugs

The European Pharmacopoeia is a single reference study for the quality control of drugs. The official standards published within it provide a legal and scientific basis for quality control in the processes of drugs development, production and marketing. However, the long experience and the multitude of studies have demonstrated that medicinal forms represent unstable dispersed systems and can undergo various manifest or non-manifest changes, leading to drug incompatibilities. Along with the physico-chemical transformations, microbiological transformations can occur with the contamination of the final product with pathogenic, conditionally pathogenic or even saprophytic germs, especially medicines that do not undergo final sterilization or are not aseptically prepared. Microbial contamination of the drug can be an indicator of the production conditions; it can cause the instability of the product through the microbial decomposition of auxiliary substances, the alteration or definitive cancellation of the therapeutic effect of the active substances, the appearance of metabolites with toxic properties, especially those fractions of endotoxins on the wall cell of gram-negative bacteria with the development of allergenic, pyrogenic substances and the induction of the danger of local orgeneral infections. An important role is attributed to the group of bile-tolerant gram-negative bacteria as representatives of microorganisms that are inadmissible in one g/ml for the absence test and for the quantitative test <10 NCP/g/ml (probable number of bacteria), inadmissible in non-sterile medicinal products, herbal medicinal products for oral use and extracts used in their preparation. Due to the diversity of medicinal forms in terms of content, method of application, and therapeutic action, these preparations fulfil the indispensable conditions for the growth of microorganisms, therefore a primary concern is to avoid microbial contamination from the technological phase to the administration phase in order to prevent complications associated with bacterial infections. The given study reveals the testing of the procedure for the rapid determination of inadmissible microorganisms in non-sterile medicinal products and herbal drugs for oral use and the extracts used in their preparation, especially microorganisms of the group Enterobacteriaceae spp.

Assessment of products of anaerobic fermentation of organic raw material from poultry last by microbiological indicators

The product of anaerobic microbiological transformation of bird droppings is a liquid suspended product (digestate), the composition of which is characterized by new chemical features acquired due to the activity of anaerobic microorganisms. This process takes place in biogas plants, and as a result of methane fermentation of bird droppings, biogas and residues of organic raw materials are formed, which are used as fertilizer. The international practice of using digestate as an organic fertilizer or soil improver for the farm’s own needs is similar to classic composts and does not require sanitary and microbiological certification, but there are voluntary certification standards, as well as various industry guidelines on the quality of organic fertilizers. The work analyzes international and national sanitary microbiological standards regarding digestates, products of processing by-products of animal husbandry and organic substances for application to the soil, in particular Regulation (EU) 2019/1009 of the European Parliament and the Council of June 5, 2019 «On establishing rules for placing fertilizers on the market EU», DSTU 7527:2014 «Poultry droppings. Technologies of biological processing. General requirements», DSTU 7938:2015 «Organic fertilizers. Agronomic requirements for the quality of fertilizers for use in organic production». Information from scientific articles, standards of individual countries and guidelines of international voluntary certification bodies regarding the assessment of digestate applied to the soil as an organic fertilizer or soil improver is summarized. It has been established that mandatory sanitary microbiological characteristics for such substances are Salmonella bacteria (Salmonellas spp.) and Escherichia spp. bacteria, as well as the standards of some countries and scientific literature recommend determining Coliform bacteria and Streptococ-cus faecalis bacteria, the presence of which indicates the possible presence of potentially dangerous strains of microorganisms. With the use of laboratory equipment, the granulation conditions of the solid fraction of the digestate were optimized to obtain granulated organic fertilizer from the sludge of the biogas plant. A microbiological analysis of granulated digestate from a biogas plant on bird droppings was carried out in order to establish its compliance with the sanitarybacteriological requirements for organic fertilizers. The presence of pathogens of infectious diseases in poultry droppings and the presence of phytopathogens in grain, which is used for the preparation of premixes, increases their probable migration into the composition of organic fertilizer in case of improper methane fermentation with violation of temperature and exposure conditions. Microbiological analysis of granulated digestate showed the absence of Salmonellas spp. and Escherichia spp. bacteria in the studied samples, but a high number of mold fungi 1.2·104±7.25·102 CFU/g was found, which may be a consequence of storage wet raw materials. In order to prevent microbiological contamination during the storage and transportation of raw materials and organic fertilizers, a necessary condition is compliance with sanitary requirements for all technological processes, starting from the conditions of keeping and feeding animals to the conditions of storage of finished products and application to the soil. The content of harmful microorganisms in the digestate of biogas plants operating on bird droppings or animal manure without litter or the addition of plant residues and chemicals depends mainly on the quality of the droppings and water. The quality of raw materials affects the quality of the digestate and is determined by the sanitary-epidemiological condition of animals and premises, microbiological contamination of feed, pre-treatment of raw materials for loading to the biogas plant. It was established that the granular digestate from bird droppings meets the requirements of Ukrainian standards DSTU 7527:2014 regarding organic fertilizers from poultry droppings and DSTU 7938:2015 regarding organic farming, which allows for further substantiation of optimal application technologies. To control the secondary bacterial contamination of organic raw materials during the storage process, the effectiveness of the use of commercial biological preparations was evaluated. The perspective of using commercial microbial preparations, in particular MycoHelp, to control mold fungi of the genus Penicillum spp. in the technologies of processing by-products of agriculture into organic fertilizers and preventing spoilage of finished products during storage.

Co-Removal of Perfluorooctanoic Acid and Nitrate from Water by Coupling Pd Catalysis with Enzymatic Biotransformation.

PFAS (poly- and per-fluorinated alkyl substances) represent a large family of recalcitrant organic compounds that are widely used and pose serious threats to human and ecosystem health. Here, palladium (Pd0)-catalyzed defluorination and microbiological mineralization were combined in a denitrifying H2-based membrane biofilm reactor to remove co-occurring perfluorooctanoic acid (PFOA) and nitrate. The combined process, i.e., Pd-biofilm, enabled continuous removal of ∼4 mmol/L nitrate and ∼1 mg/L PFOA, with 81% defluorination of PFOA. Metagenome analysis identified bacteria likely responsible for biodegradation of partially defluorinated PFOA: Dechloromonas sp. CZR5, Kaistella koreensis, Ochrobacterum anthropic, and Azospira sp. I13. High-performance liquid chromatography-quadrupole time-of-flight mass spectrometry and metagenome analyses revealed that the presence of nitrate promoted microbiological oxidation of partially defluorinated PFOA. Taken together, the results point to PFOA-oxidation pathways that began with PFOA adsorption to Pd0, which enabled catalytic generation of partially or fully defluorinated fatty acids and stepwise oxidation and defluorination by the bacteria. This study documents how combining catalysis and microbiological transformation enables the simultaneous removal of PFOA and nitrate.

Effectiveness of biogeosorbents based on mineral carriers for treatment oil-contaminated soil

Methods for cleaning oil-contaminated areas include the use of sorbents, the effectiveness of which is enhanced by the immobilization of hydrocarbon-oxidizing microorganisms on their surface. Biogeosorbents are obtained on the basis of mineral raw materials (analcime- and glauconite-containing rocks and thermally activated vermiculite) and hydrocarbon-oxidizing bacteria of the genera Pseudomonas and Microbacterium extracted from contaminated soils of the Murmansk region. The number of immobilized bacteria on the studied carriers remains high throughout 9 months of storage, and the bacterial film on the surface of mineral carriers persists for 12 months of storage in an air-dry state. When storing biogeosorbents, no special conditions or additional preparation are required before use. Mineral carriers have a stimulating effect on the height of seedlings and the length of roots of test plants. When biogeosorbents are added, the number of bacteria capable of microbiological transformation of petroleum products increases, and the degree of soil purification from petroleum hydrocarbons at the initial stage (during the first 30 days) increases. The most effective is the introduction of thermally activated vermiculite and glauconite-containing rock with immobilized hydrocarbon-oxidizing bacteria. The use of a biogeosorbent based on thermally activated vermiculite can reduce the cleaning time to 20–22 months, and based on glauconite-containing rock – up to 17 months, while without treatment this period will be at least 29 months.

Biotransformation of Δ1-Progesterone Using Selected Entomopathogenic Filamentous Fungi and Prediction of Its Products' Bioactivity.

This research aimed at obtaining new derivatives of pregn-1,4-diene-3,20-dione (Δ1-progesterone) (2) through microbiological transformation. For the role of catalysts, we used six strains of entomopathogenic filamentous fungi (Beauveria bassiana KCh J1.5, Beauveria caledonica KCh J3.3, Isaria fumosorosea KCh J2, Isaria farinosa KCh KW1.1, Isaria tenuipes MU35, and Metarhizium robertsii MU4). The substrate (2) was obtained by carrying out an enzymatic 1,2-dehydrogenation on an increased scale (3.5 g/L) using a recombinant cholest-4-en-3-one Δ1-dehydrogenase (AcmB) from Sterolibacterium denitrificans. All selected strains were characterized by the high biotransformation capacity for the used substrate. As a result of the biotransformation, six steroid derivatives were obtained: 11α-hydroxypregn-1,4-diene-3,20-dione (3), 6β,11α-dihydroxypregn-1,4-diene-3,20-dione (4), 6β-hydroxypregn-1,4-diene-3,11,20-trione (5), 6β,17α-dihydroxypregn-1,4-diene-3,20-dione (6), 6β,17β-dihydroxyandrost-1,4-diene-3-one (7), and 12β,17α-dihydroxypregn-1,4-diene-3,20-dione (8). The results show evident variability of the biotransformation process between strains of the tested biocatalysts from different species described as entomopathogenic filamentous fungi. The obtained products were tested in silico using cheminformatics tools for their pharmacokinetic and pharmacodynamic properties, proving their potentially high biological activities. This study showed that the obtained compounds may have applications as effective inhibitors of testosterone 17β-dehydrogenase. Most of the obtained products should, also with a high probability, find potential uses as androgen antagonists, a prostate as well as menopausal disorders treatment. They should also demonstrate immunosuppressive, erythropoiesis-stimulating, and anti-inflammatory properties.

MICROBIOLOGICAL TRANSFORMATION OF PHOSPHORUS IN THE ROOT ZONE OF SUNFLOWER UNDER THE ACTION OF BACILLUS SP. 2473 AND DIFFERENT DEGREES OF CROP FERTILIZATION

Objective. To study the peculiarities of the microbiological transformation of phosphorus compounds in the root zone of sunflower plants under the action of Bacillus sp. 2473 and different degrees of crop fertilization. Methods. Field experiment; microbiological (accounting for bacteria capable of dissolving insoluble phosphate complexes with Ca2+, Al3+, Fe3+ and hydrolysing organic phosphates in the rhizosphere soil of sunflower plants); biochemical (determination of soil phosphatase activity); chemical (determination of phosphorus content in soil and plants); statistical. Results. Under the conditions of the field experiment on leached chornozem, it was established that during the growing season of sunflower in the soil after the introduction of Bacillus sp. 2473 into the agrocenosis, the number of bacteria capable of dissolving insoluble complexes of phosphates with Ca2+, Al3+, Fe3+ and bacteria hydrolysing organic forms of phosphates increases compared to the indicators of the control variants. Phosphatase activity increases during the growing season of plants and reaches the highest values during the seed ripening phase. The lowest levels of phosphorus content in the rhizosphere soil of sunflower plants were registered after presowing inoculation with Bacillus sp. 2473. The content of Р2О5 decreased from 0.25 mg Р2О5/dm3 of the soil solution (in the control) to 0.21 mg Р2О5/dm3 in the phase of 7–8 leaves under the action of the inoculant; from 0.42 mg Р2О5/dm3 to 0.31 mg Р2О5/dm3 in the flowering phase; from 0.24 mg Р2О5/dm3 to 0.21 mg Р2О5/dm3 in the seed ripening phase, respectively, which indicates the strengthening of phosphorus assimilation by bacterized plants. The optimal agricultural background, taking into account the effect of fertilizers on the development of phosphate-mobilizing microorganisms, is the use of mineral fertilizers in a rate not exceeding N90P90K90. Conclusion. Under the influence of the phosphate-mobilizing bacterium Bacillus sp. 2473, the processes of phosphorus transformation are activated in the root zone of sunflower plants, which is indicated by an increase in the number of phosphate-mobilizing bacteria, phosphatase activity and the degree of phosphate mobility in the rhizosphere soil of plants. As a result, the assimilation of phosphorus by plants is enhanced, which is confirmed by the increase in its removal with crop yield from 47.3 kg/ha to 74.8 kg/ha, while the efficiency of phosphorus nutrition of plants is 53.8 % (against the background of N90P90K90).

Deciphering the Interactions in the Root–Soil Nexus Caused by Urease and Nitrification Inhibitors: A Review

Optimizing nitrogen (N) availability to plants is crucial for achieving maximum crop yield and quality. However, ensuring the appropriate supply of N to crops is challenging due to the various pathways through which N can be lost, such as ammonia (NH3) volatilization, nitrous oxide emissions, denitrification, nitrate (NO3−) leaching, and runoff. Additionally, N can become immobilized by soil minerals when ammonium (NH4+) gets trapped in the interlayers of clay minerals. Although synchronizing N availability with plant uptake could potentially reduce N loss, this approach is hindered by the fact that N loss from crop fields is typically influenced by a combination of management practices (which can be controlled) and weather dynamics, particularly precipitation, temperature fluctuations, and wind (which are beyond our control). In recent years, the use of urease and nitrification inhibitors has emerged as a strategy to temporarily delay the microbiological transformations of N-based fertilizers, thereby synchronizing N availability with plant uptake and mitigating N loss. Urease inhibitors slow down the hydrolysis of urea to NH4+ and reduce nitrogen loss through NH3 volatilization. Nitrification inhibitors temporarily inhibit soil bacteria (Nitrosomonas spp.) that convert NH4+ to nitrite (NO2−), thereby slowing down the first and rate-determining step of the nitrification process and reducing nitrogen loss as NO3− or through denitrification. This review aims to provide a comprehensive understanding of urease and nitrification inhibitor technologies and their profound implications for plants and root nitrogen uptake. It underscores the critical need to develop design principles for inhibitors with enhanced efficiency, highlighting their potential to revolutionize agricultural practices. Furthermore, this review offers valuable insights into future directions for inhibitor usage and emphasizes the essential traits that superior inhibitors should possess, thereby paving the way for innovative advancements in optimizing nitrogen management and ensuring sustainable crop production.

Studying the Composition and Genesis of Organic Matter in Bottom Sediments of Polluted Small Watercourses in Khabarovsk City Territory

The distribution of organic matter, hydrocarbons, phytopigments, and ecological-trophic groups of microorganisms was studied in the bottom sediments of ten small tributaries of the Amur R. near Khabarovsk. The water showed high concentrations of organic matter, varying from 44.47 to 279.3 mg/L. The concentration of Corg in bottom sediments varied from 1.9 to 23.1% in different types of sediments; the amount of hydrocarbons reached 5081 mg/kg, exceeding the background level by a factor of up to 50. Studies of the molecular composition of hydrocarbons in sediments revealed in some streams the predominance (up to 100% of the total) of light (C8–C13) n-alkanes, typical of oil products and the products of vegetation combustion. High-molecular compounds dominated in HC composition in most watercourses, including n-alkanes, genetically associated with terrestrial vegetation, and heavy fractions of oil products with various levels of microbial degradation. Volatile organic compounds were quantitatively dominated by the products of microbiological transformation (acetaldehyde and methanol). In terms of the concentration of sedimentary pigments (up to 400 µg/g), the sediments of the majority of watercourses belong to the hypereutrophic type. The total abundance of microorganisms in water varied from 2.7 to 488.0 thousand CFU/mL; in sediments, it was distributed symbatically, but ranged from 0.1 to 19.3 million CFU/g. The number of heterotrophic bacteria in bottom sediments correlated with the parameter of overload of the self-purification capacity (r = 0.718), and the number of oil-oxidizing bacteria correlated with hydrocarbon concentration (r = 0.967), thus confirming the indication properties of this bacterial group.

Current Trends and Perspectives in Microbial Bioconversions of Steroids.

The microbiological transformation of sterols is currently the technological basis for the industrial production of valuable steroid precursors, the so-called synthons, from which a wide range of steroid and indane isoprenoids are obtained by combined chemical and enzymatic routes. These compounds include value-added corticoids, neurosteroids, sex hormones, bile acids, and other terpenoid lipids required by the medicine, pharmaceutical, food, veterinary, and agricultural industries.Progress in understanding the molecular mechanisms of microbial degradation of steroids, and the development and implementation of genetic technologies, opened a new era in steroid biotechnology. Metabolic engineering of microbial producers makes it possible not only to improve the biocatalytic properties of industrial strains by enhancing their target activity and/or suppressing undesirable activities in order to avoid the formation of by-products or degradation of the steroid core, but also to redirect metabolic fluxes in cells towards accumulation of new metabolites that may be useful for practical applications. Along with whole-cell catalysis, the interest of researchers is growing in enzymatic methods that make it possible to carry out selective structural modifications of steroids, such as the introduction of double bonds, the oxidation of steroidal alcohols, or the reduction of steroid carbonyl groups. A promising area of research is strain engineering based on the heterologous expression of foreign steroidogenesis systems (bacterial, fungal, or mammalian) that ensure selective formation of demanded hydroxylated steroids.Here, current trends and progress in microbial steroid biotechnology over the past few years are briefly reviewed, with a particular focus on the application of metabolic engineering and synthetic biology techniques to improve existing and create new whole-cell microbial biocatalysts.

Effects of Agricultural Management of Spent Mushroom Waste on Phytotoxicity and Microbiological Transformations of C, P, and S in Soil and Their Consequences for the Greenhouse Effect.

The huge volumes of currently generated agricultural waste pose a challenge to the economy of the 21st century. One of the directions for their reuse may be as fertilizer. Spent mushroom substrate (SMS) could become an alternative to manure (M). A three-year field experiment was carried out, in which the purpose was to test and compare the effect of SMS alone, as well as in multiple variants with mineral fertilization, and in manure with a variety of soil quality indices—such as enzymatic activity, soil phytotoxicity, and greenhouse gas emissions, i.e., CO2. The use of SMS resulted in significant stimulation of respiratory and dehydrogenase activity. Inhibition of acid phosphatase and arylsulfatase activity via SMS was recorded. SMS showed varying effects on soil phytotoxicity, dependent on time. A positive effect was noted for the growth index (GI), while inhibition of root growth was observed in the first two years of the experiment. The effect of M on soil respiratory and dehydrogenase activity was significantly weaker compared to SMS. Therefore, M is a safer fertilizer as it does not cause a significant persistent increase in CO2 emissions. Changes in the phytotoxicity parameters of the soil fertilized with manure, however, showed a similar trend as in the soil fertilized with SMS.

Influence of Agricultural Systems on Microbiological Transformation of Organic Matter in Wheat Winter Crops on Typical Black Soils

Influence of Agricultural Systems on Microbiological Transformation of Organic Matter in Wheat Winter Crops on Typical Black Soils

Environmentally significant indicators of mountain meadow soils in Azerbaijan

The most widespread soils in the Republic of Azerbaijan are mountain-meadow soils. The aim of the research was a comprehensive and comparative study of morphodiagnostic parameters, physical and chemical properties, as well as the biochemical activity of natural and anthropogenically modified biogeocenoses of the Kedabey region. The area has unique flora and fauna. Surroundings of the villages Gara Murad, Kichik Garamurad, Saratovka and others were investigated. The research was carried out on virgin and cultivated lands in villages. The degree of mineralization of the rivers Zayamchay and Chekhrichay ranges from 140 to 430 mg. The groundwater level in these areas exceeds 2 m, salinization processes are active. A herbarium was collected and the floristic composition of natural cenoses was determined. Invertebrates were also collected and the dominant composition of the fauna of natural cenoses was determined. Of the saprophages in these biocenoses, woodlice of the genus Hemilepisthus and Armadillidium are widely used. The most intensive decomposition of the remains of cereal vegetation is observed in the soil of the coastal strip (65.9%). In the natural cenosis, the rate of destruction of saltwort and salt-tolerant grass vegetation reaches 44.3%. The main role in the destruction of plant remains is played by a group of saprphages, which actively use plant litter. The decomposing material reaches its final stage of microbiological transformation. The duration and amount of CO2 in different soil horizons were also studied. It has been established that with increasing depth, the amount of carbon dioxide decreases. The hydrolytic activity of invertase and urease enzymes in the studied soils can be assessed as very weak. Comparative results of all these agrochemical studies helped to develop virgin soils in agriculture on the plains and achieve high productivity.

RESEARCH OF THE INFLUENCE OF THE SOIL ALGAE BIOFETERLIZE ON THE TOXICITY OF PESTICIDE RESIDUES WITH THE HELP OF BIOTESTS

The problem of pesticide residues on agricultural land does not lose its relevance, as new drugs appear that can be toxic to the natural environment. Biopreparations that have restorative properties in the soil are widely used in the world. The use of biological preparations of microbial origin can cause a combination of various processes that can contribute to the improvement of soil properties, its remediation, etc. Especially important from the ecological point of view is the reduction of the manifestation of toxic properties of pesticide residues in the soil. Biopreparation Soil algae is a microbial biopreparation obtained by cultivating Noctoc commune bacteria using the appropriate technology. In turn, Noctoc commune bacteria have the ability to activate the processes of microbiological activity of the soil. To study the effect of the biological preparation Soil algae, field (application of the biological preparation in various concentrations to fields with a known pesticide background) and laboratory (conducting biotesting to find out the effect of the biological preparation on the toxic properties of pesticides) studies. Biotesting was carried out by various methods to determine the effect of the biological preparation at various stages of growth and development of agricultural crops, on the processes of microbiological transformation in the soil. The toxicity of pesticide residues was determined in a typical medium-loamy chernozem after a field study conducted on the basis of the Agronomic Research Station of the NUBiP of Ukraine. Determination of the effect of biofertilizer Soil algae on soil toxicity was carried out using various methods, namely: determination of soil phytotoxicity on watercress, red-tip radish, peas, and durum wheat crops; determination of the inhibitory effect of biofertilizer on the growth of higher plants; study of the total number of soil microorganisms; research of the nitrifying ability of the soil according to the Kravkov method and the inhibitory effect on soil mineralization. Phytotoxicity of typical medium-loam chernozem soil decreased with increasing drug concentration, but only up to a certain limit. The rate of the biological preparation of 8 l/ha led to an increase in the number of germinated seeds of watercress, radish, peas and durum wheat. This can be evidenced by the ability of Noctoc commune bacteria to influence processes in the soil, which contribute to reducing the toxic properties of pesticide residues in the soil.

Insights into the Biosynthesis of Nanoparticles by the Genus Shewanella.

The exploitation of microorganisms for the fabrication of nanoparticles (NPs) has garnered considerable research interest globally. The microbiological transformation of metals and metal salts into respective NPs can be achieved under environmentally benign conditions, offering a more sustainable alternative to chemical synthesis methods. Species of the metal-reducing bacterial genus Shewanella are able to couple the oxidation of various electron donors, including lactate, pyruvate, and hydrogen, to the reduction of a wide range of metal species, resulting in biomineralization of a multitude of metal NPs. Single-metal-based NPs as well as composite materials with properties equivalent or even superior to physically and chemically produced NPs have been synthesized by a number of Shewanella species. A mechanistic understanding of electron transfer-mediated bioreduction of metals into respective NPs by Shewanella is crucial in maximizing NP yields and directing the synthesis to produce fine-tuned NPs with tailored properties. In addition, thorough investigations into the influence of process parameters controlling the biosynthesis is another focal point for optimizing the process of NP generation. Synthesis of metal-based NPs using Shewanella species offers a low-cost, eco-friendly alternative to current physiochemical methods. This article aims to shed light on the contribution of Shewanella as a model organism in the biosynthesis of a variety of NPs and critically reviews the current state of knowledge on factors controlling their synthesis, characterization, potential applications in different sectors, and future prospects.

Possibility of conservation of urine as a source of drinking water in water supply systems of space and ground inhabited objects

Life support systems for long-term closed objects can be created either on the basis of consumed water reserves, or on the basis of regeneration processes. Urine can be used as a regenerated source of drinking water. But urine is a good breeding ground for many microorganisms, therefore, to preserve it in its native form, conservation is necessary in order to prevent microbiological transformation and precipitation. The article discusses the possibility of preserving urine with a composition consisting of a 05% solution of plumbagin in trichloroacetic acid and an 11% solution of chromic anhydride in sulfuric acid in a ratio of 1: 9 at the rate of 5 ml per 1 liter of urine.

Effect of the effects of different doses of mineral fertilizers on the number of ecological-trophic groups of microorganisms

The results of studies on the effect of mineral fertilizers on the number of ecological and trophic groups of microorganisms and the yield of winter wheat in the zone of unstable moisture in the Stavropol Territory are presented. The soil of the experimental site is ordinary chernozem, a powerful low-humus heavy-loam, the precursor is pure steam. Mineral fertilizers have been applied in various doses for 30 years, and the aftereffect of fertilizers has been studied since 2006. The total number of microorganisms in the aftereffect of nitrogen or phosphorus fertilizers alone was low (5.53–8.0 mln columnforming units). The number of microorganisms that transform organic forms of nitrogen in the aftereffect of nitrogen or phosphorus nutrition alone ranged from 2.62 to 4.16 mln column-forming units, and using mineral forms of nitrogen from 2.91 to 4.32 mln column-forming units. The full dose of fertilizers significantly increased the number of microorganisms that transform nitrogen compounds in the soil by an average of 15.5 mln column-forming units. The maximum total number of microorganisms was obtained in the aftereffect of high doses of nitrogen against the background of P 120 K 120 and phosphorus together with N 120 K 120 — 28.58 mln column-forming units and 30.21 mln column-forming units, respectively. The coefficient of mineralization in the studied soils is greater than one. With the unilateral introduction of nutrients in the soil, the intensity of microbiological processes decreases, сoefficient of microbiological transformation of organic matter — 3,94–8,64.

Study of biotransformation of cholesterol 3β-methyl ether by mycobacteria Mycobacterium sp.

The influence of exogenous factors on the selectivity of biotransformation of cholesterol 3β-methyl ether by Mycobacterium sp. was studied. The main product of the microbiological transformation was Δ5-dehydroepiandrosterone 3β-methyl ether. The presence of methyl-β-cyclodextrin in the bacterial growth medium led to a change in the ratio of the reaction products and an increase in the yield of Δ4-androstene-3,17-dione. Aliphatic saturated and unsaturated carboxylic acids were also formed in the course of biotransformation.

Biochemical Stability of Water-Soluble Organic Matter in Tundra Soils of the Khibiny Mountains during Postfire Succession

The dynamics of the content of water-soluble organic matter (WSOM) and its resistance to microbiological transformation in the Entic Folic Podzol of the postfire succession in the dwarf-shrub mountain tundra of the Khibiny Mountains are studied. A medium-intensity fire does not cause a statistically significant decrease in the soil WSOM content as compared to the reference plot. The activity of WSOM mineralization is mainly determined by the WSOM properties rather than by the microbial community. The dynamics of biodegradation is adequately described by a two-component first-order exponential model with a statistically significant existence of fast-mineralized (mean residence time, <1 day) and slow-mineralized (mean residence time, 33 to 111 days) pools. The maximum share of the fast pool is typical of the soil immediately after a fire and smoothly decreases during further postfire succession. During biodegradation, a biokinetic selection of the aromatic hydrophobic compounds most resistant to microorganisms is observed, while the simple nitrogen-containing components of WSOM are the first to be consumed by microorganisms.