Prikladnaâ biohimiâ i mikrobiologiâ

The article presents the characteristics, composition of metabolites and biotechnological properties of Bacillus amyloliquefaciens including structure, biochemical, ecological, genetic properties, application in plant growing, food industry, medicine, as an alternative to conventional antibiotics. Furthermore, the review addresses environmental applications of B. amyloliquefaciens such as bioprotection in vegetable storage, as plant growth promoters and protectors, and as bioremediation agents. The review aims to understand the characteristics, genetic tools, and metabolic capabilities of B. amyloliquefaciens, highlighting its potential as a base cell for synthetic biology, metabolic engineering, and protein expression. We discuss the role of the bacteria in the production of chemicals, enzymes, and other industrial bioproducts, as well as their applications in medicine, such as combating pathogenic bacteria and promoting gut health. In agriculture, B. amyloliquefaciens has shown potential as a biofertilizer, biocontrol agent with antifungal, antibacterial, insecticidal, antiviral properties, and stress tolerance enhancer for various crops. Despite its many potential applications, B. amyloliquefaciens remains underexplored. The review highlights the need for further research and development of advanced engineering methods and gene editing technologies designed specifically for B. amyloliquefaciens, which will ultimately allow its full potential to be realized in scientific and industrial contexts.

γ-Hydroxybutyrate dehydrogenase (GBDH) is an enzyme belonging to the oxidoreductase class, catalyzing the reversible conversion of succinic semialdehyde (SSA) to γ-hydroxybutyric acid (GHB). It has been established that in maize seedlings, GBDH has mitochondrial (73.7%) and cytoplasmic localization (26.3%). Two homogeneous preparations of GBDH isoforms were obtained from 7-day-old maize seedlings. The purified GBDH1 preparation had a native molecular mass of 60.3 kDa (Mr of individual subunits ~15 kDa). GBDH2, a heteromer with a molecular mass of ~286 kDa, consisted of subunits with Mr ranging from 52 to 66 kDa. The optimal pH values for the obtained enzymes differed: for GBDH1, the optimum pH for the oxidation reaction of γ-hydroxybutyrate was 9.0, while for GBDH2, the optimum pH was 7.0. The kinetics of the enzymatic reaction of GHB conversion to succinic semialdehyde follows the Michaelis-Menten equation. The Km value for GBDH1 with γ-hydroxybutyric acid was 0.31 ± 0.01 mM, and for NAD⁺ it was 0.47 mM ±0.02. For GBDH2, the Km value with the substrate GHB was 0.7 ± 0.03 mM, and the Km for NAD⁺ was 0.19 ± 0.01 mM. It was shown that CaCl₂ and KCl increased the activity of GBDH1, while MgCl₂ had a minor inhibitory effect. The catalytic activity of GBDH2 increased in the presence of CaCl₂, KCl, and MgCl₂. The study has both fundamental significance, expanding knowledge about the properties of GBDH and its role in plant cell metabolism, and applied significance — data on the mechanisms of regulation of GBDH work can be used to develop methods for increasing the productivity and resistance of plants to unfavorable environmental factors.

The colloidal chemical and antibacterial properties of aqueous dispersions of silver nanoparticles stabilized by surfactin and rhamnolipids isolated from B. amyloliquefaciens and P. fluorescens were studied. The isolated biosurfactants were identified by thin layer chromatography and Fourier transform infrared spectrometry. Using the methods of UV-visible spectrophotometry, transmission electron microscopy and dynamic light scattering, the colloidal chemical characteristics of the resulting dispersions were studied. Optimal ratios of the precursor substances were found in which the used biosurfactants perform as effective stabilizers of dispersions of silver nanoparticles and ensure their aggregative stability for at least two months. It was shown that the studied dispersions have antibacterial activity against gram-positive B. subtilis and gram-negative P. aeruginosa and E. coli. A comparative assessment of the antibacterial activity of silver nanoparticles stabilized by biosurfactants and traditional silver-containing preparations, such as a silver nitrate solution and a dispersion of silver nanoparticles stabilized by citrate, was carried out. Furthermore, dispersions stabilized with surfactin showed the highest antibacterial activity, comparable to the effect of a silver nitrate solution, which is associated with their good colloidal stability. In addition, high antibacterial activity of dispersions of silver nanoparticles stabilized with biosurfactants isolated from Bacillus and Pseudomonas bacteria against strains of the other genus was discovered. An explanation of the observed phenomenon is given and the prospects for its application in medicine are proposed.

There are numerous publications indicating an increase in the expression level of heat shock proteins (HSP) in oncological diseases. Therefore, the development of methods for indicating HSP as a marker of oncological diseases is promising. In this work, phage antibodies specific to HSP of a mouse myeloma cell line were obtained. For the first time, using a compact acoustic sensor, the effect of the conductivity of the measurement medium on the registration of an analytical signal during the interaction of phage antibodies with HSP was studied. The possibility of registering a specific interaction “HSP-phage antibodies” in suspensions with a conductivity of 50-1180 μS/cm was experimentally established. Control experiments were conducted to assess of mass load on the sensor. The results obtained are promising for the development of acoustic sensor systems in the HSP indication.

The effect of fermentation with three bacterial preparations: BK-Uglich-K, BK-Uglich-AB and BK-Uglich-P (Russia) on solubility, emulsifying activity, emulsion stability, foaming and foam stability of isolates preparated from two varieties of peas was studied. It has been shown that fermentation with bacterial cultures can increase the solubility of isolates at pH 3 by 4 to 17.5 times, at pH 4 — more than 3 times, at pH 5 — by 23% to 80%, at pH 6 — by 27% to 43%, at pH 7 — by 18% to 27%. Fermentation increased the index of emulsifying activity of isolates at pH 5 by 37% (in one of the varieties), the stability index of the emulsion at pH 3 by 19% to 28%, at pH 4 — by 17%, at pH 5 — by 18% (in one of the varieties), at pH 6 — by 16% to 35%. Fermentation increased the foaming of isolates at pH 3 by 2.2 times, at pH 4 by 1.4 to 2.4 times, at pH 5 and 6 by 1.8 to 4 times, at pH 7 by 2.1 to 2.4 times; at the same time, the stability of the foam of isolates at pH 4 increased by 11% to 22%, at pH 5 — by 11% to 13%, at pH 6 — by 15% (in one of the varieties), at pH 7 — 28% (in one of the varieties). The results obtained made it possible to select bacterial preparations to improve the parameters of pea protein isolates intended for the manufacture of various food products: pea cola (BK-Uglich-P), analogues of fermented milk products and analogues of milk (BK-Uglich-AB).