Applied Biochemistry and Microbiology最新文献

Among the diverse biological activities of fatty acids (FAs), the ability to kill or inhibit the growth of microorganisms can be distinguished. Even though the antibacterial mechanisms of fatty acids are not fully understood, the most common target of action is the cell membrane, where FAs mediate an increase in permeability and subsequent cell lysis, leading to disruption of the electron transport chain, uncoupling of oxidative phosphorylation, and inhibition of enzymatic activity and nutrient intake. In addition to acting on cell membranes, FAs can disrupt the metabolic processes of microorganisms, inhibit DNA/RNA replication, and affect the expression of virulence genes. In addition, nontraditional mechanisms of the antimicrobial action of FAs are currently being described, such as the inhibition of horizontal gene transfer, quorum sensing, and the disruption of the efflux pump. The variety of antimicrobial mechanisms and the wide range of their activity determine the high biotechnological potential of fatty acids and make further studies of the mechanisms of action on biological systems relevant.

The effect of Bacillus velezensis M66 and Bacillus subtilis 26D bacteria on the resistance of potato plants to the necrotrophic fungus Alternaria solani (the causative agent of early blight) was studied. The accumulation of viable bacterial cells of these strains in the internal tissues of the potato stem, roots, and tubers over a long period of time was demonstrated for the first time. A significant reduction in the area affected by the early blight on leaves inoculated with plant endophytes, as well as inhibition of the pathogen growth under the action of bacterial strains, was detected, which can be explained by the synthesis of lipopeptide antibiotics (the genes responsible for the synthesis of which were found by the PCR method) and proteolytic enzymes (the activity of which was demonstrated in vitro). The formation of plant resistance under the influence of inoculation with B. subtilis 26D and B. velezensis M66 was accompanied by an accumulation of hydrogen peroxide in the first hours after plant infection with A. solani spores and by a decrease in this index at the late stages of pathogenesis due to an increase in the activity of catalase and peroxidases. Limitation of the fungus spread was accompanied by an increase in the activity of proteinase inhibitors in plants, which probably decreased the negative effect of proteolytic enzymes of the necrotrophic pathogen A. solani. It can be assumed that the inoculation of plants with bacterial cells of the B. velezensis M66 strain contributed to the formation of resistance of potato plants to the early blight by efficient priming of the phytoimmune potential, which is comparable to the B. subtilis 26D strain (successfully used in the field conditions), an active component of the Fitosporin-M biopreparation.

The results of studies of the effectiveness of various methods of protecting mammoth tusks from microbiological contamination under long-term storage conditions are presented. When analyzing swabs taken from the surfaces of mammoth tusk samples before exposure, the landscape of isolated microorganisms was dominated by bacteria of the genera Bacillus, Chryseobacterium, and Enterobacter with biocontamination of bone tissue caused mainly by microorganisms from the external environment (air, anthropogenic impact, etc.). Of the proposed options for protection against biocontamination, the method that showed the greatest effectiveness was the treatment of mammoth tusks with a hydrophobic-biocide composition, followed by mechanical isolation in plastic film. When using this method of protection, the total contamination of mammoth tusk samples after six months of exposure in various conditions decreased by 4–5 times.

The effect of inoculation of healthy hydroponic seed mini-tubers and super-elite reproduction seed tubers with the endophytic bacterium Bacillus subtilis 10-4 on the resistance of plants and stored tubers to diseases was studied. A search for clusters of genes associated with the synthesis of antimicrobial secondary metabolites in the genome of strain 10-4 was carried out. A prolonged protective effect of 10-4 against diseases of leaves (alternariosis) and stored tubers (scab, fusarium) of potatoes was revealed. Metagenomic analysis of the ITS region showed a decrease in the species composition and the proportion of phytopathogenic fungi in plant leaves and stored tubers under the influence of 10-4 with maximum effect during inoculation of healthy mini-tubers. Using the anti-SMASH program, the gene clusters responsible for the synthesis of a wide range of secondary metabolites with antimicrobial activity (type III polyketides, nonribosomal peptide synthetases, betalactones, sactypeptides, rantipeptides, nonribosomal peptide metallophores, transAT-polyketide synthetases, and terpenes) were identified in the genome of strain 10-4. It was revealed that the main antimicrobial compounds of 10-4, which play an important role in the biocontrol of diseases and plant protection, are surfactin, fengycin, bacillibactin, bacillaene, subtilosin A, and bacilysin. In addition, using the CARD database, a wide range of antimicrobial resistance genes with different mechanisms of action were predicted in strain 10-4. In general, the method of pre-sowing treatment of healthy hydroponically grown seed mini-tubers with 10-4 increases the efficiency of bacterial inoculation and ensures long-term protection of tubers during storage and reduces the risk of disease transmission to new generations of plants.

This article discusses recent advances in the study of fungal biogenic elicitors, examines their structural diversity and mechanisms of immune response, and analyzes the prospects for commercial application. Attention is focused on hydrophilic elicitors (exo- and endo-β-glycans, secreted peptides), lipophilic elicitors (ergosterol and cerebrosides), and secondary metabolites (phytotoxins), which are involved in the intercellular interactions of the pathogen and the host plant and have a great immunostimulating potential. The use of nanoparticles and nanoemulsions that enhance the bioavailability of elicitors as a promising strategy in the preparation of their formulations is discussed.

Biocatalytic synthesis of fumaric acid from glucose by the previously engineered E. coli strain FUM1.0 (pMW119-kgd) (E. coli MG1655 ∆ackA-pta, ∆ldhA, ∆adhE, ∆ptsG, P_L-glk, P_tac-galP, ∆fumB, ∆fumAC, poxB::P_L-pycA^Bs, pMW119-kgd) was optimized. The maximal yield of the target substance was achieved upon its synthesis through a variant of the tricarboxylic acid cycle mediated by the action of heterologous 2-ketoglutarate decarboxylase. The enhanced expression of the genes encoding components of the succinate dehydrogenase enzymatic complex did not markedly affect the biosynthetic characteristics of the producing strain. A positive effect of decreasing the intracellular ATP supply on the conversion of the carbohydrate substrate into the target product was demonstrated. The activation of the futile cycle of pyruvate–phosphoenolpyruvate–pyruvate due to an increase in the expression of the ppsA gene led to a slight increase in the yield of fumaric acid. Upon uncoupling the H⁺-ATP synthase complex subunits resulting in ATP formation cessation via oxidative phosphorylation, due to deletion of the atpFH genes, the molar yield of fumaric acid from glucose demonstrated by the strain functioning in the whole-cell biocatalyst mode reached 92%.

The development of antiviral drugs due to the high risk of rotavirus infections, especially for newborns, has attracted a lot of attention. This review is devoted to consideration of additional and promising tools for controlling human rotavirus infection (HRI) in newborns—passive oral immunization. Vaccination of animals allows us to obtain immunoglobulins in the form of colostrum and use them against human diseases. The use of bovine colostrum as an additional therapeutic agent against HRI in newborns is analyzed.

The effect of fermentation with three bacterial preparations, BK-Uglich-K, BK-Uglich-AV, and BK-Uglich-P (Russia), on solubility, emulsifying activity, emulsion stability, foaming, and foam stability of isolates from two pea varieties was studied. The fermentation with bacterial cultures was shown to increase the solubility of isolates by 4 to 17.5 times at pH 3, over 3 times at pH 4, by 23 to 80% at pH 5, by 27 to 43% at pH 6, and by 18 to 27% at pH 7. The fermentation increased the index of emulsifying activity of the isolates at pH 5 by 37% (in one of the varieties). The stability index of the emulsion grew by 19 to 28% at pH 3, by 17 at pH 4, by 18% (in one of the varieties) at pH 5, and by 16 to 35% at pH 6. The 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, and at pH 7 by 2.1 to 2.4 times. At the same time, the stability of the foam of isolates grew at by 11 to 22% pH 4, by 11 to 13% at pH 5, by 15% (in one of the varieties) at pH 6, and by 28% (in one of the varieties) at pH 7. The results made it possible to select bacterial preparations to improve the parameters of the pea protein isolates intended for the manufacture of various food products, particularly, pea cola (BK-Uglich-P), analogues of fermented milk products and analogues of milk (BK-Uglich-AV).

The discovery of bacteriophages allowed the development of new ways to control the bacterial number and to assess bacterial viability. The most obvious application of bacteriophages is the treatment of human bacterial infections (phage therapy). The advantage of phage therapy is the extreme specificity of phages, since they interact with and infect only certain bacteria without affecting other bacteria or cell lines of other organisms. The advances in phage biology led to the widespread use of specific phage–host interactions in medicine and the agricultural and food industries. Thus, bacteriophages are an alternative to antibiotics for fighting infections and destroying pathogenic bacteria. This work has demonstrated for the first time the potential of a compact acoustic sensor system for assessing the impact of bacteriophages on microbial cells and the bacteriophage sensitivity of the latter. It has been shown that the developed system can be used to evaluate the activity of bacteriophages against microbial cells within 5 min without taking into account the time of cultivation of microbial cells for analysis. The results obtained are promising for further development of the acoustic sensory system in phage therapy.

The effect of chitosan–caffeic acid (Ch–CA) conjugate separately and in combination with a mixture of Bacillus subtilis 47 on the plant defense against PVY under optimal hydration and water deficit in soil was evaluated. The treatments of Ch–CA and Ch–CA+B. subtilis 47 on healthy potato plants under optimal soil moisture conditions demonstrated the accumulation of proline and phenolic compounds, as well as the activation of PPO, which collectively led to an increase in the nonspecific plant defenses. The application of Ch–CA resulted in a reduction of PVY infection in potato plants grown under both optimal and soil moisture-deficient conditions and led to an increase in the potato mini-tuber’s mass. The combination of B. subtilis 47 and Ch–CA proved effective in reducing the infection level exclusively under conditions of soil water deficit. It has been demonstrated that the primary factor influencing the development of resistance in potato plants to PVY under moisture-limiting conditions is associated with an elevated peroxidase activity and alterations in antioxidant activity within plant tissues.