Alexander Yu Maksimov

The use of hydrolytic enzymes is one of the most promising methods for combating bacterial biofilms. However, the use of native enzymes is limited by the rapid loss of activity under unfavorable conditions. Immobilization of enzymes on carbon nanoparticles enhances their stability, allows for biocatalyst reuse, and creates a synergistic effect due to the intrinsic antimicrobial properties of the nanomaterials. The aim of this investigation was to create and comparatively analyze conjugates of acid and alkaline proteases with carboxylated multiwalled carbon nanotubes (MWCNTs-COOH) and to assess their effect on the formation and destruction of E. coli VKM B-3858D biofilms. The immobilization efficiency and kinetics of enzyme adsorption on the support were quantified by determining the protein concentration using the Bradford assay. The morphology and dispersion of the resulting conjugates were analyzed using atomic force microscopy (AFM). Protease activity was determined by a modified Anson method using the Folin–Ciocalteu reagent. Biofilm biomass was determined using crystal violet staining. The binding efficiency of the acid protease to MWCNTs-COOH was shown to reach 93%, which is significantly higher than that of the alkaline protease. The highest degree of immobilization was observed at a protein concentration of 117–338 μg/mL (10–20 mg/mL of the enzyme preparations). The interaction of the acid protease with the carbon nanoparticles increased dispersion, reducing the size of aggregates from ~1 μm to ~68 nm. As a result, acid protease conjugates with MWCNTs-COOH significantly reduced the biofilm biomass compared to both the enzyme-free control and the native enzyme. Alkaline protease, unlike the acid protease, destroys mature biofilms, and immobilization on MWCNTs-COOH enhances this ability. Native alkaline protease and acid protease conjugates with MWCNTs-COOH are effective in combating the biofilm formation of Gram-negative bacteria, while alkaline protease conjugates are suitable for disrupting mature biofilms.

Environmental pollution from polymers is reaching alarming levels. Nitrile‐butadiene rubber (NBR), widely used in medical glove manufacturing, contributes significantly to plastic and microplastic pollution. Nitrile gloves have become a major component of COVID‐19 pandemic‐related waste. In this study, we demonstrated the ability of haloalkalitolerant, nitrile‐utilizing Rhodococcus qingshengii IEGM 1416 and R. erythropolis IEGM 1417 to grow on a mineral medium containing NBR as the sole nitrogen source. Scanning electron microscopy and colony‐forming unit (CFU) counting confirmed the development of Rhodococcus biofilms on this material, representing the first step in polymer biodegradation. After UV and freeze‐thaw pretreatment of NBR, biofilm biomass for R. qingshengii IEGM 1416 and R. erythropolis IEGM 1417 reached (7.28 ± 0.48) × 10 ⁶ and (6.27 ± 0.72) × 10 ⁶ CFU/cm ² , respectively. Using attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, we identified structural changes in NBR following UV/freeze‐thaw treatment and subsequent 1‐month cultivation. The appearance of amide groups in the polymer structure resulted from the transformation of nitrile groups by bacterial nitrile hydratases. Oxidative aging of the material was observed after both UV irradiation and bacterial growth; notably, the effect varied between the different sides of the NBR due to structural heterogeneity. Enzymes from haloalkalitolerant nitrile‐utilizing rhodococci induce chemical changes in NBR, corresponding to the initial stages of backbone oxidation and nitrile group transformation.

Photothermal therapy combines the effects of near-infrared laser (NIR laser) and strong light-absorbing materials to combat pathogens and unwanted biofilms. Graphene derivatives have a negative effect on microorganisms, and the combination of NIR laser irradiation and carbon nanomaterials (CNMs) can enhance their antibacterial effect. This investigation is devoted to the determination of the expression level of bacterial stress response genes (soxS and rpoS) under graphene oxide (GO), reduced graphene oxide (rGO), and NIR laser irradiation (1270 nm). GO, rGO and NIR laser irradiation separately and irradiation in the presence of graphene derivatives cause an increase in the expression level of rpoS associated with the general stress response of bacteria. GO and rGO do not change the expression level of soxS associated with the cell response to oxidative stress, and decrease it in the presence of a strong oxidizing agent paraquat (PQ). The expression of soxS increases under laser irradiation, but decreases under NIR laser irradiation in combination with graphene derivatives. The effect of GO, rGO, and NIR laser irradiation on the formation and eradication of E. coli biofilms was studied. NIR laser with GO and rGO suppresses the metabolic rate and decreases the intracellular ATP content by 94 and 99.6%, respectively. CNMs are shown to reduce biofilm biomass and the content of extracellular polymeric substances (EPSs), both exopolysaccharides and protein in the biofilm matrix. Graphene derivatives in combination with NIR laser irradiation may be an effective means of combating emerging and mature biofilms of Gram-negative bacteria.

Background. Uneven distribution and lack of water is one of the global problems faced all over the world. Particularly relevant is the uneven water supply for crop production. In agricultural practice, the problem of water shortage can be solved by introducing preparations based on hydrogels into the soil. The use of hydrogels makes it possible to reduce the frequency of irrigation and soil compaction, stop erosion, leaching of nutrients and biogenic elements, optimize soil aeration and microbiological activity. However, agricultural sorption polymers available on the market do not solve the problems of plant nutrition and health improvement. The purpose of these experiments is to determine the effect of complex preparations based on a polymer carrier and a strain of phosphate-mobilizing bacteria Bacillus mycoides A7, which has amylase and lipase activity, on the growth of tomato seedlings under light culture conditions. Materials and research methods. To assess the effect of different variants of the biological product on the growth of tomatoes of the early ripe variety "Balkonnoe chudo", the morphometric parameters and biochemical parameters of plants were measured. In each variant, the mean value and standard deviation were determined. Proline concentration in leaves was measured as described by Bates et al., 1973. Protein concentration was determined by the method of Bradford, 1976. The activity of the antioxidant peroxidase enzyme was evaluated by the method of Chance and Maley, 1955. Catalase activity was measured by the method of Nakano and Asads, 1981. Results. It has been shown that the addition of both Bacillus mycoides A7 biomass and the obtained complex preparations to the soil has a pronounced growth-stimulating effect on model plants. Inoculation of a liquid suspension of B. mycoides A7 culture stimulated the growth of model plants to a greater extent than all preparations of pure hydrogel, but to a lesser extent than all complex preparations of this culture with hydrogels. It was also established that the variants with the introduction of a bacterial culture and a complex preparation contain lower concentrations of stress factors, which indicates the normalization of metabolic processes and the general condition of model plants. Conclusion. The study of the effect of complex preparations based on polyacrylamide hydrogel and a culture of phosphate-mobilizing bacteria Bacillus mycoides A7, a producer of amylase and lipase enzymes, on the growth of tomato plants of the early ripening "Balkonnoe chudo" variety under light culture conditions showed that this culture, as part of a complex preparation, normalizes the physiological hygienic state and stimulates plant growth.

In this work, we investigate the catalytic properties and immobilization of enzyme preparations containing lipase of haloalkalotolerant bacteria Pseudomonas peli and Bacillus aequororis. Lipase was isolated from the P. peli 3-T and B. aequororis 5-DB followed by its immobilization on either carboxymethylcellulose, activated chitosan or fodder yeast. The pH-dependence of native enzyme activity and thermostability, as well as the residual activity upon immobilization and drying of immobilized product, were determined. The lipase activity from both sources enhances with increasing alkalinity of the reaction medium. Specifically, P. peli 3-T lipase exhibited no activity in an acidic medium, and B. aequororis 5-DB lipase exhibited around 20% of maximum activity at a pH value of 6–7. The isolated lipase has a rather high thermostability; thus, P. peli 3-T lipase fully retains its initial activity upon heating to 60°C and 70°C for 1 h. Moreover, 15 min exposure to temperatures of 80°C and 90°C leads to an activity decrease of 73% and 83%, respectively. Activated chitosan and fodder yeast are the most promising of the studied excipients for enzyme immobilization. Drying of the immobilized lipase product on the activated chitosan showed retention of 3% and 46% of the native enzyme activity derived from P. peli 3-T and B. aequororis 5-DB, respectively. In the case of fodder yeast, these values were 2% and 64%, respectively.

Добыча калийно-магниевых солей сопровождается процессами техногенного засоления, что приводит к трансформации микробиоценозов и изменению их геохимической роли в формировании свойств почв. В пойменных ландшафтах в солончаке вторичном, характеризующимся очень сильным засолением (сумма токсичных солей достигает 17%) преобладают бактерии Shewanella, Acidocella и Acidophilium и Thiomicrospira, обитающие в морских и высокоминерализованных средах и способных восстанавливать железо, марганец, продуцировать сульфиды. В результате взаимодействия микроорганизмов, почв и высокоминерализованных вод, обогащенных сульфат-ионами и железом, в таежных ландшафтах в солончаковых почвах возникает гидротроилитовый горизонт и формируются сульфидные...

Releasing multi-walled carbon nanotubes (MWCNTs) into ecosystems affects the biofilm formation and metabolic activity of bacteria in aquatic and soil environments. Pristine (pMWCNTs), oleophilic (oMWCNTs), hydrophilic (hMWCNTs), and carboxylated (cMWCNTs) carbon nanotubes were used to investigate their effects on bacterial biofilm. A pronounced probiofilm effect of modified MWCNTs was observed on the Gram-negative bacteria of Pseudomonas fluorescens C2, Acinetobacter guillouiae 11 h, and Alcaligenes faecalis 2. None of the studied nanomaterials resulted in the complete inhibition of biofilm formation. The complete eradication of biofilms exposed to MWCNTs was not observed. The functionalization of carbon nanotubes was shown to change their probiofilm and antibiofilm effects. Gram-negative bacteria were the most susceptible to destruction, and among the modified MWCNTs, oMWCNTs had the greatest effect on biofilm destruction. The number of living cells in the biofilms was assessed by the reduction of XTT, and metabolic activity was assessed by the reduction of resazurin to fluorescent resorufin. The biofilms formed in the presence of MWCNTs reduced tetrozolium to formazan more actively than the control biofilms. When mature biofilms were exposed to MWCNTs, dehydrogenase activity decreased in Rhodococcus erythropolis 4-1, A. guillouiae 11 h, and A. faecalis 2 in the presence of pMWCNTs and hMWCNTs, as well as in A. guillouiae 11 h exposed to cMWCNTs. When mature biofilms were exposed to pMWCNTs, hMWCNTs, and cMWCNTs, the metabolism of cells decreased in most strains, and oMWCNTs did not have a pronounced inhibitory effect. The antibiofilm and probiofilm effects of MWCNTs were strain-dependent.

Работа посвящена разработке конструкции отражательного элемента для амплитудного волоконно-­оптического датчика вибрации, а также тестированию работоспособности такой конструкции. В работе описана математическая модель поперечных колебаний, помогающая определить частоты резонанса в зависимости от длины свободного волокна. Реализована отражающая поверхность, представляющая собой периодическую структуру ниобата лития и участков, покрытых золотом. Представлена компоновка и конструкция датчика вибрации с возможностью перестройки частоты резонанса, а также продемонстрирована экспериментальная схема. Сигнал, полученный при помощи описанной схемы, поддается обработке преобразования Фурье, рассчитанные частоты совпадают с частотами колебаний источника вибраций. Получена амплитудно-­частотная характеристика, частота резонанса коррелирует с частотами, полученными математической моделью (коэффициент корреляции Пирсона равен 0,977). Результаты реализации настоящей разработки важны для нового междисциплинарного направления – ​агробиофотоники, дают ключ к более тонкому и точному изучению виброчувствительности животных и вибротропизма растений.

In recent decades, there has been a significant increase in the number of fungal diseases. This is due to a wide spectrum of action, immunosuppressants and other group drugs. In terms of frequency, rapid spread and globality, fungal infections are approaching acute respiratory infections. Antimycotics are medicinal substances endorsed with fungicidal or fungistatic properties. For the treatment of fungal diseases, several groups of compounds are used that differ in their origin (natural or synthetic), molecular targets and mechanism of action, antifungal effect (fungicidal or fungistatic), indications for use (local or systemic infections), and methods of administration (parenteral, oral, outdoor). Several efforts have been made by various medicinal chemists around the world for the development of antifungal drugs with high efficacy with the least toxicity and maximum selectivity in the area of antifungal chemotherapy. The pharmacokinetic properties of the new antimycotics are also important: the ability to penetrate biological barriers, be absorbed and distributed in tissues and organs, get accumulated in tissues affected by micromycetes, undergo drug metabolism in the intestinal microflora and human organs, and in the kinetics of excretion from the body. There are several ways to search for new effective antimycotics: - Obtaining new derivatives of the already used classes of antimycotics with improved activity properties. - Screening of new chemical classes of synthetic antimycotic compounds. - Screening of natural compounds. - Identification of new unique molecular targets in the fungal cell. - Development of new compositions and dosage forms with effective delivery vehicles. The methods of informatics, bioinformatics, genomics and proteomics were extensively investigated for the development of new antimycotics. These techniques were employed in finding and identification of new molecular proteins in a fungal cell; in the determination of the selectivity of drugprotein interactions, evaluation of drug-drug interactions and synergism of drugs; determination of the structure-activity relationship (SAR) studies; determination of the molecular design of the most active, selective and safer drugs for the humans, animals and plants. In medical applications, the methods of information analysis and pharmacogenomics allow taking into account the individual phenotype of the patient, the level of expression of the targets of antifungal drugs when choosing antifungal agents and their dosage. This review article incorporates some of the most significant studies covering the basic structures and approaches for the synthesis of antifungal drugs and the directions for their further development.