Biology subjects

Bazhenov, S. V.

Publications and source records attributed to Bazhenov, S. V..

5 recordsLinked to original sources

bioRxiv2026

Vibrio aquamarinus sp. nov., a luminous marine bacteria isolated from the Black Sea Vibrio aquamarinus sp. nov., a luminous marine bacteria isolated from the Black Sea

Three novel bioluminescent bacterial strains, VNB-15T, VNB-16 and SChm4, were isolated from water of the Black Sea (Russia) and intestines of the Black Sea horse mackerel. Cells of the isolated strains are motile Gram negative slightly curved rods with single polar flagellum. The temperature range for growth was 10-35{degrees}C, the optimum being 20-25{degrees}C. The pH range for growth was 6.0-9.0, the optimum being 7.0-8.0. The bacteria were able to grow in the presence of 0.5 to 5.0% NaCl (w/v), the optimum being 1.0-4.0% (w/v). Phylogenetic analysis based on comparison of 16S rRNA sequences shows these strains to have kinship with the species Vibrio jasicida, Vibrio hyugaensis, Vibrio alginolyticus, Vibrio campbelli, Vibrio rotiferianus, Vibrio harveyi and Vibrio owensii with sequence similarity from 99.6 to 98.0%. Phylogenetic analysis based on comparison of the sequences of genes gyrB, recA, pyrH, gapA, rpoA, mreB, ftsZ, topA shows that the strains VNB-15T, VNB-16 and SChm4 to form a cluster within the V. harveyi clade and belong to a new species of the Vibrio genus. Comparison of the complete genomic sequence of VNB-15T with typical strains of nearby species also indicates that VNB-15T belongs to a separate species (maximum similarity 98% with V. hyugaensis and 96% with V. jasicida). VNB-15T differs from closely related species by its ability to utilize glucose, mannitol, inositol, sorbitol, rhamnose and sucrose, and to form lysine decarboxylase, ornithine decarboxylase, lipase, acid phosphatase, -glucosidase, {beta}-glucosidase and N-acetyl-{beta}-D-glucosaminidase enzymes. Based on phylogenetic analysis and phenotypic characteristics, Vibrio aquamarinus sp. nov. is proposed. The type strain is VNB-15T (= VKPM B-11245T = DSM 26054 T). RepositoriesThe GenBank accession numbers for the gapA, 16S rRNA, gyrB, pyrH, rpoA, recA, mreB, ftsZ, topA genes sequences of strain VNB-15T are JQ319116-JQ319121, KX242381, KX 242384, KX242387, respectively. The GenBank accession numbers for the gapA, gyrB, pyrH, recA, rpoA,16S rRNA, mreB, ftsZ, topA genes sequences of strain VNB-16 are KP221561-KP221566, KX242382, KX 242385, KX242388 respectively. The GenBank accession numbers for the 16S rRNA, gapA gyrB, rpoA, recA, pyrH, mreB, ftsZ, topA genes sequences of strain SChm4 are KX242375-KX242380, KX242383, KX 242386, KX242389, respectively. The GenBank/EMBL/DDBJ accession numbers for the housekeeping gene sequences used in this study are detailed in supplementary Table S1, Figures S1-S8. The genome of Vibrio aquamarinus sp. nov. VNB-15T, comprising two chromosomes and a plasmid, has been assembled and deposited in the NCBI database under the submission number SUB14585067

molecular biology↗

bioRxiv2025

The capability of plant-bacteria consortia to reduce the genotoxicity of unsymmetrical dimethylhydrazine in the environment

Unsymmetrical dimethylhydrazine (UDMH) despite its proven high toxicity continues to be used in rocket technology and some other areas of human activity. In this work, the ability of plant-bacteria consortia to reduce the genotoxicity of UDMH incomplete oxidation products was investigated. Genotoxicity was assessed using a specific lux-biosensor Escherichia coli MG1655 pAlkA-lux sensitive to DNA alkylation in cell. For microbiological biodegradation, the Bacillus subtilis KK1112 strain was obtained by the isolation from soil with a subsequent selection for resistance to high UDMH concentrations (more than 5000 MAC). Its ability to biodegrade UDMH was shown by observing the reduction of DNA alkylation of the KK1112-treated UDMH. The ability of KK1112 cells to act in a bacterial-plant consortium with following fodder halo-phytes was studied: Bromus inermis Leyss, Medicago varia Mart. and Phleum pratense L. A synergistic reduction in the alkylating properties of UDMH oxidation products was observed under the combined use of bacteria and plant seedlings. The greatest effect was obtained when bacteria was used in combination with B. inermis. It was shown that KK1112 cells accelerate the seedlings development and mitigate the growth inhibition that occurs during incubation with UDMH. The obtained results indicate that it is optimal to introduce the bacterium KK1112 in combination with B. inermis plants for soils in arid climate zones during reclamation after UDMH exposure.

ecology↗

bioRxiv2025

Oxidative stress leads to Fur-mediated activation of ftnA in Escherichia coli independently of OxyR/SoxRS regulators

Ferritin FtnA is the main scavenger of Fe2+ and storage of Fe3+ in bacterial cells, together with Dps and Bfr preventing the Fenton reaction and thus protecting the cell from iron-induced oxidative stress. However, until now, it was not known how its expression is regulated under conditions of oxidative stress, and the available evidence was contradictory. To study the regulation of E. coli ftnA expression in response to oxidative stress, PftnA-luxCDABE transcriptional fusion in different strains was used. It has been shown that PftnA is induced after the addition of oxidative stress inducers. The maximum amplitude of this activation did not depend on the presence of functional genes oxyR and soxR in the cell, but completely disappeared in the absence of fur. The response is amplified in the ftnA mutant and is diminished in the FtnA-overproducing strain, which indicates that iron sequestration blocks the response. Exposure of a cell to H2O2 initially inactivates Fur and a number of iron-utilizing proteins, and derepresses iron uptake. This results in an increase in the cellular iron content with the consequent Fur reactivation, which leads to the induction of ftnA expression. Thus, oxidative stress leads to PftnA activation, which is mediated by Fur and time-delayed in comparison with OxyR-response.

molecular biology↗

bioRxiv2023

luxA gene from Enhygromyxa salina encodes a functional homodimeric luciferase

Several clades of luminescent bacteria are known currently. They all contain similar lux operons, which include the genes luxA and luxB encoding a heterodimeric luciferase. The aldehyde oxygenation reaction is catalyzed by the subunit LuxA, while LuxB is inactive. Recently, genomic analysis identified a subset of bacterial species with rearranged lux operons lacking luxB. Here, we show that the product of the luxA gene from the reduced luxACDE operon of Enhygromyxa salina is luminescent upon addition of aldehydes both in vivo in Escherichia coli and in vitro. Overall, EsLuxA is less bright compared with luciferases from Aliivibrio fischeri (AfLuxAB) and Photorhabdus luminescens (PlLuxAB), and most active with medium-chain C4-C9 aldehydes. Crystal structure of EsLuxA determined at the resolution of 2.71 [A] reveals a classical monooxygenase fold, and the protein preferentially forms a dimer in solution. The mobile loop residues 264-293, which form a {beta}-hairpin or a coil in Vibrio harveyi LuxA, form -helices in EsLuxA. Phylogenetic analysis shows EsLuxA and related proteins may be bacterial protoluciferases that arose prior to duplication of the luxA gene and its speciation to luxA and luxB in the previously described luminescent bacteria. Our work paves the way for discovery of new luciferases that have an advantage of being encoded by a single gene.

biochemistry↗

bioRxiv2020

Toxic effect of 2,2'-bis(bicyclo heptane) on bacterial cells.

Here we present the study of the genotoxic effect of a 2,2-bis(bicyclo[2.2.1]heptane) (BBH), which is promising as a fuel component for liquid rocket engines. The use of Escherichia coli lux-biosensors showed that in addition to DNA damage causing SOS-response, there is also an oxidative effect on cells. The greatest toxicity is determined by the mechanism of formation of superoxide anion radical and is detected by the lux biosensor E. coli pSoxS-lux, in which the genes of bacterial luciferases are transcriptionally crosslinked with the promoter of the soxS gene. It is assumed that the oxidation of BBH leads to the formation of reactive oxygen species, which should give the main contribution to the toxicity of this substance.

pharmacology and toxicology↗