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High efficiency of a combined preparation including synergistic polymyxin B and 4-hexylresorcinol was shown for treatment of experimental sepsis caused by an antibiotic-resistant highly virulent hypermucoid Klebsiella pneumoniae strain KPM9Pmr in mice. Complex therapy with polymyxin B (1 mg/kg) and 4-hexylresorcinol (30 mg/kg) led to cure in 80%; in 20% of these mice, no bacterial cells were found. After treatment with polymyxin B alone, only 50% animals survived and all of them contained bacterial cells. Comparative analysis of the results of monotherapy and combined treatment indicates that 4-hexylresorcinol not only increases the efficiency of antibiotic, but also minimizes persistence of the infection agent and therefore, the risk of development of antibiotic resistance.

The process of a breakdown in a saline solution in a pin – plane electrode geometry is investigated for the interelectrode gap of 1 cm and a 3% NaCl concentration in the water. Single voltage pulses of about 2 ms duration and amplitude of a few kilovolts are applied to the gap. A current of up to units of kiloamps is passed through the gap. It is shown that a necessary condition for the discharge to form is the availability of gaseous cavities in the electrolyte. The stages of discharge development are investigated at the voltages applied to the gap, which exceed the threshold value (at which plasma forms in the gas cavities). An analysis of the influence of the processes of formation and collapse of gas cavities in the solution and plasma in the cavities on the shape and value of the discharge current is performed.

The results of investigations of a low-pressure hollow-cathode glow discharge with a hot filament (thermionic cathode) inside the cavity are presented. The current-voltage characteristics (CVCs) of the discharge and the dependences of the current delivered to the thermionic and hollow cathodes on the discharge burning voltage are obtained at different gas pressures and filament currents. It is shown that the major fraction of the current is transferred in the thermionic cathode circuit. For interpretation of the CVCs, a model is accepted, which uses a generalized coefficient (rather than a conventionally utilized secondary-emission coefficient), which includes not only the cathode bombardment with ions but also the emission current induced by an external source. An estimation is made of the discharge parameters. The model is shown to be quite consistent with the experiment.

The review presents a general description of therapeutic monoclonal antibodies, cell lines used to obtain them, characterizes the reasons for the immunogenicity of recombinant antibodies, and approaches used to eliminate the side effects of therapeutic monoclonal antibodies. The focus is on resolving the immunogenicity problems of fully human therapeutic monoclonal antibodies. The most attention are concentrated on the data of antibody-producing cell genomic editing to increase the yield of the product, the stability of expression of the recombinant protein and reduce its immunogenicity. Modern methods of site-directed modification (zinc finger method, TALEN and CRISPR/CAS9) for editing the genome of the CHO cell line are analyzed. The strategies of genomic editing choice carrying out taking into account the advances of omix technologies are discussed. Approaches to increase the life span of producer cells are considered, including an increase in the expression of anti-apoptotic signals and the deletion of proapoptotic genes, an increase in the duration of the cell cycle of cells in the G0/G1 phase. The approaches used to regulate the posttranslational modification of monoclonal antibodies are considered. Significant part of the review are devoted to the discussion of the spesificity and differences of glycosylation, galactosylation and sialization of monoclonal antibodies in different expression systems and the associated different degree of immunogenicity of monoclonal antibodies. The main approaches to the regulation of the synthesis of monoclonal antibodies at the stage of translation using non-coding RNA are considered.

Data are presented on an investigation of pulsed discharges in a solution of 30 g of NaCl per liter of distilled water. The interelectrode gap consists of the active pin electrode and the return plane electrode. The voltage pulse of positive polarity forms by means of an electric circuit where a capacitor bank of 40 μF with an initial voltage V 0 of up to 1500 V is discharged via the gap. In a range of initial voltages V 0 = (550 – 1100) V vapor cavities in a form of the microbubbles are generated near the active electrode and at the electrode surface. The microbubbles are able to merge with each other thus forming macrobubbles and vapor layers, which shield the active electrode from current passage. The process of vapor cavity generation and the effect of shielding are discussed in detail. The discharge at the vapor layer appears at the critical voltage V 0 = 1100 V. The principal prerequisite for discharge arising is that the electrode has to be completely shielded by the vapor layer and the voltage at the layer at the instant of discharge initiation has to be at least at a level of 500 V. However, when the voltage at the gap exceeds the critical value, the condition of complete shielding is not obligatory.

Neutralization of the lethal toxin of Bacillus anthracis is an important topic of both fundamental medicine and practical health care, regarding the fight against highly dangerous infections. We have generated a neutralizing monoclonal antibody 1E10 against the lethal toxin of Bacillus anthracis and described the stages of receptor interaction between the protective antigen (PA) and the surface of eukaryotic cells, the formation of PA oligomers, assembly of the lethal toxin (LT), and its translocation by endocytosis into the eukaryotic cell, followed by the formation of a true pore and the release of LT into the cell cytosol. The antibody was shown to act selectively at the stage of interaction between Bacillus anthracis and the eukaryotic cell, and the mechanism of toxin-neutralizing activity of the 1E10 antibody was revealed. The interaction between the 1E10 monoclonal antibody and PA was found to lead to inhibition of the enzymatic activity of the lethal factor (LF), most likely due to a disruption of true pore formation by PA, which blocks the release of LF into the cytosol.

This review presents various strategies to fight causative agents of infectious diseases. Species-specific programmable RNA-containing antibiotics open up new possibilities for creating next-generation of personalized drugs based on microbiome editing and can serve as a new tool for selective elimination of pathogenic bacterial species while keeping intact the rest of microbiota. Another promising approach in combating bacterial infections is genome editing using the CRISPR-Cas systems. Expanding knowledge on the molecular mechanisms of innate immunity has been actively used for developing new antimicrobials. However, obvious risks of using antibiotic adjuvants aimed at activation of the host immune system include development of the autoimmune response with subsequent organ damage. To avoid these risks, it is essential to elucidate action mechanisms of the specific ligands and signal molecules used as components of the hybrid antibiotics. Bacteriophage endolysins are also considered as effective antimicrobials against antibiotic-resistant bacteria, metabolically inactive persisters, and microbial biofilms. Despite significant advances in the design of implants with antibacterial properties, the problem of postoperative infections still remains. Different nanomodifications of the implant surface have been designed to reduce bacterial contamination. Here, we review bactericidal, fungicidal, and immunomodulating properties of compounds used for the implant surface nanomodifications, such as silver, boron nitride nanomaterials, nanofibers, and nanogalvanic materials.

High efficiency of a combined preparation including synergistic polymyxin B and 4-hexylresorcinol was shown for treatment of experimental sepsis caused by an antibiotic-resistant highly virulent hypermucoid Klebsiella pneumoniae strain KPM9Pm

The purpose of this work was to obtain genus-specific monoclonal antibodies against the

Ever decreasing efficiency of antibiotic treatment due to growing antibiotic resistance of pathogenic bacteria is a critical issue in clinical practice. The two generally accepted major approaches to this problem are the search for new antibiotics and the development of antibiotic adjuvants to enhance the antimicrobial activity of known compounds. It was therefore the aim of the present study to test whether alkylresorcinols, a class of phenolic lipids, can be used as adjuvants to potentiate the effect of various classes of antibiotics. Alkylresorcinols were combined with 12 clinically used antibiotics. Growth-inhibiting activity against a broad range of pro- and eukaryotic microorganisms was determined. Test organisms did comprise 10 bacterial and 2 fungal collection strains, including E. coli and S. aureus, and clinical isolates of K. pneumoniae. The highest adjuvant activity was observed in the case of 4-hexylresorcinol (4-HR), a natural compound found in plants with antimicrobial activity. 50% of the minimal inhibitory concentration (MIC) of 4-HR caused an up to 50-fold decrease in the MIC of antibiotics of various classes. Application of 4-HR as an adjuvant revealed its efficiency against germination of bacterial dormant forms (spores) and prevented formation of antibiotic-tolerant persister cells. Using an in vivo mouse model of K. pneumoniae-induced sepsis, we could demonstrate that the combination of 4-HR and polymyxin was highly effective. 75% of animals were free of infection after treatment as compared to none of the animals receiving the antibiotic alone. We conclude that alkylresorcinols such as 4-HR can be used as an adjuvant to increase the efficiency of several known antibiotics. We suggest that by this approach the risk for development of genetically determined antibiotic resistance can be minimized due to the multimodal mode of action of 4-HR.

The results of the comparative testing of the susceptibility of M. tuberculosis clinical strains to isoniazid, streptomycin, rifampicin and ethambutol using the TB test kit, developed in SCRAMB, (Obolensk) and the absolute concentrations method; the TB test kit and the BACTEC MGIT 960 automated system are presented in the study. A total of 629 and 220 strains, respectively, were tested. A high degree of agreement of the results was shown: 89.1-98.6% for isoniazid, 96.2-98.0% for rifampicin, 91.5-98.2% for streptomycin and 89.1-95.9% for ethambutol. The smallest number of discrepancies in the results was obtained when comparing the TB test kit and BACTEC MGIT 960. The discrepant results analysis was performed by the proportion method, PCR sequencing, or re-testing on new lots of the TB test kit and Lowenstein-Jensen medium with anti-tuberculosis drugs, after which the sensitivity, the specificity and the efficiency of the TB test kit have exceeded 95 % for all anti-tuberculosis drugs. The turnaround time with the TB test kit (median 9.25-9.9 days, ranged from 8 to13 days) was significantly shorter than that with the absolute concentration method (median 21-23 days, ranged from 20 to 28 days) and is commensurate with the turnaround time with BACTEC MGIT 960 (average 7.2 days, ranged from 5 to 12 days). The TB test kit is easy to use, does not require expensive equipment and special staff training.

Nowadays healthcare-associated infections caused Pseudomonas aeruginosa remain actual problem due to P. aeruginosa resistance to a wide range of antimicrobials and its ability to form biofilms that are 1000 times more resistant to antibiotics than free-living (plankton) cultures. P. aeruginosa biofilms forming is regulated by Quorum Sensing (QS) communication system which is controlled by inhibitors (Quorum sensing inhibitors, QSIs). An essential role in stabilization of biofilms belongs to extracellular DNA (eDNA) as a structural polyanionic polymer whereas its genetic function is not applicable. In addition, internal signal molecules c-di-GMP, cascade Gac/Rsm also participate in formation of P. aeruginosa biofilms. A review provides a detailed description of the biofilm molecular regulation by means of QS inhibitors and QS modulators of signaling molecules QS.

The development of a discharge in a point−plane gap filled with a saline solution with a salt content of 3% was studied experimentally. The duration of the voltage pulse applied to the gap was about 2 ms. Data are presented on the formation dynamics of gas microcavities at near-threshold voltages at which gas-discharge plasma appears in some microcavities. The cavities are conglomerates of microbubbles with a typical size of ≈100 μm. At the threshold voltage (≈750 V), the active electrode is covered with a gas layer and the gap voltage is in fact applied to this layer, which leads to the development of discharges in individual microbubbles. In this case, the discharge operates in the form of short current pulses. The number of microcavities filled with plasma increases as the voltage grows above the threshold value. At the plasma boundary, new microbubbles are formed, in which discharges are ignited. As a result, the plasma front propagates from the active electrode into the gap with a characteristic velocity of 103 cm/s.

The delay time to breakdown of a cold-cathode thyratron with a trigger unit based on an auxiliary steady-state low-current glow discharge was studied experimentally. The device was connected into the electric circuit according to the circuit of a classical thyratron. The main experiments were carried out at low working gas (deuterium) pressures and high anode voltages of about 40 kV. It is found that, during the triggering current pulse or commutation of the main discharge current, the auxiliary discharge in the trigger unit passes from the stable segment of the current-voltage characteristic into the regime with a reduced operating voltage. Spontaneous reverse transitions from this regime are also possible. On the other hand, the initial conditions of the auxiliary discharge affect the delay time to thyratron breakdown and lead to the jitter in the total delay time to breakdown relative to the triggering pulse. The total delay time amounts to 100 ns, the jitter in delay time being within 15 ns.

This paper deals with the investigation of the discharge in the solution of 0.9% NaCl in water for the conditions, when the voltage at the gap is in a vicinity of the so-called critical voltage at which the discharge in a thin vapor layer at the surface of active electrode appears. In the experiments, the critical voltage is at a level of (180–200) V. Most of the data correspond to powering the discharge by the bipolar voltage pulses of 5 s duration. The main attention is centered on the nonsteady (transient) processes and on the forms of the discharge operation. For the voltage pulses of negative polarity, when the metal electrode is the cathode, the discharge is sustained in the glow regime with the occasional glow-to-spark transitions. At the positive polarity of the voltage, the surface of liquid inside the vapor layer plays a role of cathode in the gas-discharge gap. In these conditions, the process of the glow-to-spark transition is suppressed and the discharge is sustained in the glow regime.

Results from studies of a low-current glow discharge with a hollow cathode are presented. A specific feature of the discharge conditions was that a highly emissive tablet containing cesium carbonate was placed in the cathode cavity. In the absence of a tablet, the discharge ignition voltage was typically ≥3.5 kV, while the burning voltage was in the range of 500–600 V. The use of the tablet made it possible to decrease the ignition voltage to 280 V and maintain the discharge burning voltage at a level of about 130 V. A model of the current sustainment in a hollow-cathode discharge is proposed. Instead of the conventional secondary emission yield, the model uses a generalized emission yield that takes into account not only ion bombardment of the cathode, but also the emission current from an external source. The model is used to interpret the observed current−voltage characteristics. The results of calculations agree well with the experimental data. It is shown that, in some discharge modes, the external emission current from the cathode can reach 25% of the total discharge current.

Nonstationary processes in atmospheric-pressure glow discharge manifest themselves in spontaneous transitions from the normal glow discharge into a spark. In the experiments, both so-called completed transitions in which a highly conductive constricted channel arises and incomplete transitions accompanied by the formation of a diffuse channel are observed. A model of the positive column of a discharge in air is elaborated that allows one to interpret specific features of the discharge both in the stationary stage and during its transition into a spark and makes it possible to calculate the characteristic oscillatory current waveforms for completed transitions into a spark and aperiodic ones for incomplete transitions. The calculated parameters of the positive column in the glow discharge mode agree well with experiment. Data on the densities of the most abundant species generated in the discharge (such as atomic oxygen, metastable nitrogen molecules, ozone, nitrogen oxides, and negative oxygen ions) are presented.

An efficient method of highly sensitive, specific determination of botulinic type A neurotoxin (which allows the detection of a toxin in a concentration from 1 pg/mL (10 fg per one PCR reaction) was created based on the technology of immuno-PCR. Solid phase consisting of paramagnetic organo–silicious particles carrying a detection complex of the toxin heavy chain with a pair of polyclonal antibodies to it was the most appropriate in the optimal scheme of the analysis. One of the antibodies bound to DNA (which is a matrix for PCR amplification) by means of biotin–neutravidin interaction. Matrix DNA was a molecular “net” generated by biotinylated DNA molecules with tetravalent neutravidin. The binding signal was detected by real time PCR (by the TaqMan method). An immuno-PCR method for determination of type A botulotoxin was developed.

Aptamers are short single-stranded oligonucleotides which are selected via targeted chemical evolution in vitro to bind a molecular target of interest. The aptamer selection technology is designated as SELEX (Systematic evolution of ligands by exponential enrichment). SELEX enables isolation of oligonucleotide aptamers binding a wide range of targets of interest with little respect for their nature and molecular weight. A number of applications of aptamer selection were developed ranging from biosensor technologies to antitumor drug discovery. First aptamer-based pharmaceutical (Macugen) was approved by FDA for clinical use in 2004, and since then more than ten aptamer-based drugs undergo various phases of clinical trials. From the medicinal chemist’s point of view, aptamers represent a new class of molecules suitable for the development of new therapeutics. Due to the stability, relative synthesis simplicity, and development of advanced strategies of target specific molecular selection, aptamers attract increased attention of drug discovery community. Difficulties of the development of next-generation antibiotics basing on the conventional basis of combinatorial chemistry and high-throughput screening have also amplified the interest to aptamer-based therapeutic candidates. The present article reviews the investigations focused on the development of antibacterial aptamers and discusses the potential and current limitations of the use of this type of therapeutic molecules.

Category A select agents continue to be major threat to human population both as naturally occurring diseases and as potential weapon of bioterrorists. Anthrax and botulism are probably the most threatening agents as both have virtually uncontrolled natural reservoirs from which they can be isolated and propagated. Available specific antitoxin therapy of both diseases is outdated; its efficiency is questionable as well as safety of reactogenic or human-derived components used in treatment. Highly sensitive toxin detection techniques are still not as widespread as it needed for timely alerting medical services. There is urgent need of pre-exposure prophylaxis and postexposure specific antitoxin therapy for anthrax and botulism. Analysis of modern studies in the field suggests oligoclonal antibodies acting against receptor-binding toxin subunits and nucleic acid aptamers as allosteric inhibitors of metlloproteolytic toxin components as the most promising candidates for development of efficient antitoxin therapy

Shiga toxin-producing Escherichia coli (STEC) food-borne infections are reported worldwide and represent a serious problem for public healthcare. In the Russian Federation there is little information on epidemiology and etiology of STEC-infections as well as on molecular-genetic peculiarities of STEC pathogens. Objective : Our aim was to describe a food-borne outbreak as hemorrhagic colitis (HC) along with hemolytic uremic syndrome (HUS), enterocolitis, and acute gastroenteritis in children in St.-Petersburg in 2013. Methods : Epidemiological, microbiological, molecular-genetic and bioinformati с methods were applied. Results : Objects to study were clinical specimens, milk and food samples, as well as STEC strains isolated during the outbreak. The outbreak of food-borne infection was found to be caused by STEC-contaminated raw milk as confirmed by epidemiological analysis, detection of STEC DNA and isolation of relevant pathogens in milk and sick children fecal specimens. The whole-genome sequencing revealed two groups of pathogens, E. coli O157:H7 and E. coli О 101:H33 among collected strains. Group I strains were attributed to the previously known sequence type ST24, while group II strains belonged to the previously non-described sequence type ST145. In strain genomes of both groups there were identified nucleotide sequences of VT2-like prophage carrying stx2 с gene, plasmid enterohemolysin gene, and gene of the STEC main adhesion factor intimin. Gene of intimin gamma was identified in E. coli O157:H7 strains and intimin iota 2 in E. coli O101:H33 strains. The latter previously was identified only in enteropathogenic E. coli (EPEC) strains. Conclusion : The additional knowledge of epidemiology and biology of STEC pathogens would assist clinicians and epidemiologists in diagnosing, treating and preventing hemorrhagic colitis.

A test bench for studying two-electrode spark gaps rated at a voltage of 300 kV and a pulse repetition rate of up to 10 Hz and operating in air at elevated pressure. The typical time of pulse charging of a capacitive storage in the bench equals about 100 μs. The object of investigation is a spark gap the operating stability of which at a level of 10% of the rate voltage is achieved by initiating a corona discharge at the prebreakdown stage. It is shown that unstable operation is due to the accumulation of nitrogen oxides in the gap. To maintain the oxide content at an acceptable level, continuous gas purging is applied and necessary gas flow rates are estimated.

An enzyme immunoassay-based test system for Y. pestis V antigen detection was developed. The specificity and sensitivity of this system met the requirements for medical immunobiological preparations for the identification of causative agents of highly fatal diseases. The sensitivity of the test system was assessed, and its high specificity was also demonstrated: the test system did not detect bacterial cells of closely related (four Y. pseudotuberculosis strains) and heterologous microorganism strains. The test system developed was able to detect the V antigen at concentrations as low as 2.0 ng/mL in cells of nine experimental Y. pestis cultures. The obtained preparation can be recommended for use in laboratory diagnostics of plaque.

A model of a controlled conversion of polysaccharide Vi-antigen of S. typhi into zwitterionic antigen is proposed. The immunological properties of modifications of this antigen conjugated to a protein support were studied.

Monoclonal antibodies (MCAs) to the E. coli O157: H7 O-antigen characterized by a high level of activity and specificity have been obtained. We investigated their biochemical properties and diagnostic importance. Based on these results, we constructed a latex assay using monoclonal antibodies for the identification of enterohemorrhagic E. coli belonging to the O157 serogroup. This assay was tested on pure cultures of 31 strains of closely related and other microorganisms. The designed assay allows one to detect microbial cells of E. coli O157:H7 at concentrations of 2.5 × 105 cell/ml and higher.

Nucleic acid-based aptamers are widely accepted as promising tools for development of a plethora of diagnostic and therapeutic preparations, as well as means of environmental monitoring. The properties of aptamers permit them to be regarded as fully synthetic analogs of antibodies. Moreover, certain properties of aptamers render them superior to antibodies in terms of the development of new diagnostic and monitoring systems that combine high sensitivity and specificity with high reproducibility and inexpensive manufacture. In particular, aptamer-based technologies for detection of biomolecules and whole microorganisms can be employed in solving the problems of highly sensitive express diagnostics of bacterial pathogens. The present review summarizes the current state of the techniques developed for aptamer-based detection of bacteria and their components and discusses the potential of their practical application.

Category A select agents continue to be major threat to human population both as naturally occurring diseases and as potential weapon of bioterrorists. Anthrax and botulism are probably the most threatening agents as both have virtually uncontrolled natural reservoirs from which they can be isolated and propagated. Available specific antitoxin therapy of both diseases is outdated; its efficiency is questionable as well as safety of reactogenic or human-derived components used in treatment. Highly sensitive toxin detection techniques are still not as widespread as it needed for timely alerting medical services. There is urgent need of pre-exposure prophylaxis and postexposure specific antitoxin therapy for anthrax and botulism. Analysis of modern studies in the field suggests oligoclonal antibodies acting against receptor-binding toxin subunits and nucleic acid aptamers as allosteric inhibitors of metlloproteolytic toxin components as the most promising candidates for development of efficient antitoxin therapy.

Magnetic immunosorbents (MIS) have been designed using antianthrax monoclonal antibodies immobilized on aluminum silicate—iron oxide matrix activated by sodium perchlorate. MIS allows us to concentrate the analyzed microorganism and to decontaminate culture from concomitant microflora. Diagnostic test systems constructed on the basis of MIS were tested on pure Bacillus anthracis cultures and in the model experiments. The results testify to the high specificity and sensitivity (102–103 spore/ml) of the designed test systems.

Point mutations associated with isoniazid resistance in Mycobacterium tuberculosis (MTB) have been analyzed in codon 315 of the katG gene by conventional polymerase chain reaction (PCR) using primers containing locked nucleic acid (LNA) modified nucleotides. Purity and structure of primers containing 5 LNA monomers of 17 nucleotides in length were characterized by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) and a 17-mer duplex formed by two complementary oligonucleotides was characterized by the method of thermal denaturation. The duplex containing five LNA monomers per each strand was characterized by a higher melting temperature than it was expected using extrapolation of theoretical calculation for nucleotide modification of one strand of the duplex. Detection of any of six possible mutations in katG codon 315 (i.e. discrimination between sensitive and resistant MTB) requires just one PCR employing a set of two primers with one LNA-modified primer; this is an important advantage of oligonucleotides containing LNA over unmodified nucleotides: employment of multiplex PCR would require up to 12 primers. Problems of control of oligonucleotide modification by LNA monomers are discussed.

Isoniazid resistance in Mycobacterium tuberculosis (MBT) is associated with point mutations in codon 315 of the katG gene. Two PCR technique were developed for detection of point mutations in codon 315. Most frequent point mutations (AGC → ACC and AGC → AGA) were identified in codon 315 by using two sets of primers, either of which included an additional competitive blocking primer with a 3′-terminal phosphate group in order to prevent nonspecific amplification. PCR with a set of two primers, one of which contained five locked nucleic acid monomers (LNA), permits one to detect any of six known mutations in codon 315 of katG and, thereby, discriminate between isoniazid-sensitive and resistant MBT isolates. The structure and purity of the 17-nt long LNA-containing oligonucleotides were characterized by MALDI-TOF mass spectrometry; and the 17 bp duplex formed by two LNA-containing complementary oligonucleotides was analyzed by thermal denaturation.

Lipid-1a-phosphatase LpxE cleaves the phosphate group in the first position of lipid A of lipopolysaccharide in Gram-negative bacteria, which reduces toxicity and reactogenicity of bacterial endotoxin while maintaining its immunogenicity. Treatment with these enzymes in preparations of recombinant proteins obtained in bacterial producers, for example, in E. coli, may find application in the purification techniques of various pharmaceutical substances, primarily various protein components of vaccines. This work is devoted to the creation of an efficient method for obtaining an F. tularensis LpxE soluble protein in a heterologous expression system based on E. coli. Optimization of the bacterial production of LpxE enzyme is achieved by creating a SUMO-LpxE chimeric protein in which the SUMO polypeptide acts as a folding catalyst and an affinity target carrier for purifying the expression product. An additional increase in the level of synthesis of LpxE and reduction of its toxicity for a bacterial strain is achieved against the background of superproduction of bacterial periplasmic chaperones encoded by an auxiliary low copy plasmid. Subsequent chromatographic purification of the target recombinant protein involves the use of affinity metal chelate chromatography and a SUMO protease cleavage step of the SUMO peptide carrying the His6 N-terminal peptide with the reduction of natural primary structure of the enzyme. The developed method makes it possible to obtain a highly purified active enzyme LpxE F. tularensis with a yield of 0.26 g/L of bacterial culture without fermentation.