Applied Biochemistry and Microbiology最新文献

In this work, the ability of endophytic bacteria Bacillus subtilis (Cohn.) (strains 26D and Ttl2) to suppress the reproduction of potato virus Y (PVY) and potato virus X (PVX) on tomato plants (Solanum lycopersicum L.) and to stimulate the growth of infected plants by regulating the redox balance was demonstrated. The bacterial strains B. subtilis 26D and B. subtilis Ttl2 reduced the titer of PVY and PVX in tomato plants, restored their growth to the control values, which was accompanied by a decrease in the disease symptoms and severity. PVY and PVX disrupted the redox balance of plants for their development. However, the treatment with B. subtilis 26D and B. subtilis Ttl2 strains regulated the generation of hydrogen peroxide by changing the activity of catalase and positively affected the activity of peroxidases in tomato plants infected with PVY or PVX. This allowed us to suggest the possibility of using these strains as a basis for creating biopreparations for the protection of tomato plants from viral diseases.

Using directly engineered derivatives of previously constructed succinate-producing Escherichia coli strain SUC1.0 (pMW119-kgd) (MG1655 ∆ackA-pta, ∆poxB, ∆ldhA, ∆adhE, ∆ptsG, P_Lglk, P_tacgalP, ∆aceBAK, ∆glcB, ∆sdhAB, pMW119-kgd) the feasibility of gamma-aminobutyric acid biosynthesis from glucose by this bacterium resulting from a partial reversal of GABA-shunt was demonstrated. The formation of succinate semialdehyde from 2-ketoglutarate was ensured in the strain resulting from the expression of Mycobacterium tuberculosis 2-ketoglutarate decarboxylase gene. Conversion of succinate semialdehyde to succinic acid was prevented by the inactivation of cellular NAD⁺- and NADPH⁺-dependent succinate semialdehyde dehydrogenases. Formation of the target substance by the action of native 4-aminobutyrate aminotransferase was achieved upon the inactivation of glutamate decarboxylases A and B. Enhancement of 4-aminobutyrate aminotransferase gene expression led to an increase in the molar yield of gamma-aminobutyric acid from glucose demonstrated by the strain synthesizing the target product through the partially reversed GABA-shunt from ~11 to ~25%.

The process of bioleaching of metallurgical slag containing nickel and copper was studied at 40, 45, and 50°C. The microbial communities grown at 40 and 45°C that included Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans bacteria were used in the experiments. The microbial community, which was cultivated at 50°C, included the representatives of S. thermosulfidooxidans and Acidiplasma sp. It was demonstrated that dissolution of the solid phase, oxidation of ferrous iron by microorganisms were the largest at 45°C. At the same time, the majority of copper (95.5–100%) and nickel (92.3–100%) passed into the solution at the first day of bioleaching. The study of the kinetics of chemical leaching of non-ferrous metals over 4 h demonstrated that in the presence of 5 g/L Fe³⁺, the extraction of nickel and copper was 93.0 and 94.3%, respectively, while in the absence of Fe³⁺, 75.0% of nickel and 77.8% of copper passed into the solution.

The work is devoted to the experimental study of Arthrospira platensis culture growth in a two-stage luminostat. A new method of flow culture is presented, which allows increasing the efficiency of light energy assimilation, as well as controlling the content of photosynthetic pigments in algal biomass. At the first stage, the growth of A. platensis culture at step 1 of luminostat in the batch mode was investigated. Due to high surface and spatial irradiance, there is a prolonged exponential phase on the growth curve. The maximum specific growth rate of the culture was 0.96 1/day and the chlorophyll a and C-phycocyanin content was low: 1.37 and 2.3%, respectively. The light energy passing through the first stage varied from 2.23 to 33.24% depending on the maintained density of the quasi-continuous culture. The reduction in light flux affected the maximum productivity of A. platensis at step 2 of luminostat, which was 0.08 g/(L day). In the second experiment, cultivation was carried out in a two-stage luminostat regime, when the nutrient medium sequentially flowed through both steps. It was shown that at the second stage, due to a decrease in irradiance, there was photoadaptation of A. platensis cells consisting in a slight increase in the proportion of chlorophyll a and a significant increase in C-phycocyanin: 13.6%. The pigment content was directly influenced by the uniformity of cell irradiation, being only 8% for the second stage, which led to a decrease in productivity and an increase in the content of C-phycocyanin. The findings allow us to recommend the two-stage luminostat for solving the problems of optimization in order to obtain microalgal biomass with desired pigment composition.

Inorganic polyphosphates (polyPs) are universal regulatory compounds and participate in the control of gene expression, stress adaptation, membrane transport, and cell motility. They play an important role in bone tissue development, thrombosis and inflammation processes, signal transmission in nerve cells, and amyloid formation. These polymers participate in phosphorus homeostasis in both living cells and natural and technogenic ecosystems. PolyPs are used as fertilizers, food additives, and water treatment compounds and flame retardants. Modern, highly sensitive, and specific methods for polyP analysis are necessary for solving fundamental problems for regulation of biochemical processes and for a number of practical tasks, such as monitoring the state of environmental objects, food quality, and developing new methods for treating bone diseases, the cardiovascular system, and neurodegenerative pathologies. Currently, efficient and highly specific methods for polyP assay have been developed, such as special extraction methods, enzymatic analysis, electrophoresis, DAPI staining, and microscopic methods, including micro-X-ray analysis. NMR retains its importance, especially for determining the polymer chain length. In this review, we consider polyP analysis methods from the point of view of problems solved in the study of various biological objects, with special attention to the most modern and widespread approaches.

This study concerns the antimicrobial effects of various natural polyphenols, namely resveratrol, dihydroquercetin, dihydromyricetin, baykalein, chrysin, rutin, and daidzein, using a model test culture of Bacillus subtilis VKPM B-4419 isolated from children’s dairy products. Pretesting of polyphenols on pathogenic microorganisms, including the species Staphylococcus aureus and Escherichia coli, and fungi of Candida albicans and Aspergillus niger, showed that four of the eight compounds tested, namely daidzein, resveratrol, dihydroquercetin, and dihydroquercetin, inhibited the growth of Gram-positive S. aureus and Gram-negative E. coli. Daidzein and resveratrol at a concentration of 15 mM proved most successful against bacterial pathogens, while dihydroquercetin blocked the growth of S. aureus at a concentration of 30 mM and dihydromyricetin inhibited the growth of E. coli at 150 mM. None of the polyphenols studied inhibited the growth of the fungal pathogens. Study of the impact of natural polyphenols on the growth and viability of the model nonpathogenic Gram-positive strain of B. subtilis VKPM B-4419 confirmed that daidzein and resveratrol inhibited its growth by 45–56% compared to that in the control. It was comparable to the action of the antibiotics vancomycin and chloramphenicol. Daidzein and resveratrol formed growth-free zones upon testing with the method of diffusion into agar. Daidzein inhibited bacterial metabolism at the stationary growth stage by 26%, while the combined effect of daidzein and chloramphenicol showed an additive action up to 76%, nearly equal to the impact of the compounds separately. We conclude that the application of the bacterial test model of nonpathogenic B. subtilis VKPM B-4419 is likely to be promising for the design and prescreening of medicine, including tests for synergism and additivity of the combined action of phytochemical compounds and antibiotics.

Immobilization of lactic acid bacteria (using Enterococcus faecium as an example) in silanol-humate gels (SHG) not only increases the number of viable cells during long-term storage compared to the control (as previously shown), but also enhances their potential probiotic properties. The antagonistic activity against test strains of microorganisms (E. coli, S. aureus, and Y. lipolytica) increases up to 0.7–5 times compared to planktonic cultures. The number of E. faecium in SHG under conditions of acid and enzymatic stress, simulating the conditions of the upper parts of the human gastrointestinal tract, is maintained at a level of 30–80% of the initial level, while in the control (unstabilized preparation), almost complete cell death is observed. The technological indicators of fermented milk products obtained using E. faecium immobilized in SHG as starters are improved: the time of clot formation is reduced from 48 to 44 hours and the organoleptic assessment is improved. The safety of SHG for animals has been demonstrated when ingested at doses not exceeding 5 g/kg/day. SHG can be recommended for use in veterinary medicine and the food industry as a feed additive–adsorbent and stabilizer of probiotic cultures as components of food products.

The currently available information on the properties of proteins of the transferrin family—multifunctional cationic proteins involved in various enzymatic, immune, and regulatory processes in the bodies of mammals and humans—is reviewed. The literature on the physiological role, structure, mechanism of metal ion binding, antibacterial properties, and the prospects for the practical use of transferrins and oligopeptide derivatives is summarized.

A comparative assay of 2D gels of extracts from the Yarrowia lipolytica Po1f strain and its transformant of Y. lipolytica Po1f pUV3-Op with integrated intracellular histidine acid phytase from the Obesumbacterium proteus enterobacteria was performed. Upon the identification of protein profiles with MALDI-TOF mass spectrometry to determine differentially expressed proteins, seventeen protein zones were identified with some change in expression. Among the proteins with the decreased expression in the transformant of Y. lipolytica Po1f pUV3-Op, there were noted Peptidase M20, Carboxypeptidase, Proteasome assembly proteins Proteasome chaperone 2, and YALI0C01221p. The proteins with increased expression in the Po1f transformant pUV3-Op contained Nucleoside diphosphate kinase, proteins with chaperone properties of YALI0B15840p, glycerol kinase acetylated at the N-terminal edge of the molecule. Using the analysis of the proteomic profiles of two strains of the Y. lipolytica yeast we concluded that the protein composition of the transformant of Y. lipolytica Polf pUV3-Op carrying the phytase gene microencapsulated in a yeast cell possesses some metabolic features that let it, on the one hand, successfully synthesize and accumulate a heterologous functional target enzyme in the cells, and, on the other one, induce the response to endogenous stress caused by active synthesis and folding of a heterologous protein due to moderate suppression of proteasome degradation and promotion of chaperone protection.

The escalating threat of multidrug-resistant (MDR) pathogens necessitates urgent exploration of natural antimicrobial alternatives. This study identified a novel surfactin-producing Bacillus subtilis strain ZCK-1 isolated from environmental soil. Whole-genome sequencing revealed a 4 043 370 bp (GC content: 43.73%) encoding 4041 protein-coding genes, including biosynthetic gene clusters for lipopeptides. A surfactin extract was obtained through XAD 16N macroporous resin adsorption coupled with ethanol elution and vacuum rotary evaporation. The surfactin demonstrated potent antibacterial activity against clinically critical Gram-positive pathogens, notably Streptococcus pneumoniae, Corynebacterium striatum, and drug-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). Mechanistic studies revealed dual modes of action: disrupting bacterial membrane integrity and degrading genomic DNA. The compound exhibited remarkable thermal stability (100°C, 30 min) and tolerance to extreme pH (2.0–13.0), proteases (trypsin/pepsin), while remaining susceptible to lipase-mediated degradation. Acute oral toxicity assays in murine models confirmed biosafety (LD₅₀ > 5000 mg/kg). These findings position surfactin from B. subtilis ZCK-1 as a promising candidate for combating MDR infections in clinical and industrial settings.