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•Suboptimal, novel and toxic substrates induce oxidative stress in bacteria.•Stress regulons under the influence of ROS destabilize the bacterial genome.•ROS-induced mutagenesis and ...HGT accelerate evolution under selective pressure.•To accelerate bacterial evolution, the average mutagenesis level is favorable (∼10−8).
The review is devoted to bacterial genome destabilization by oxidative stress. The article discusses the main groups of substances causing such stress. Stress regulons involved in destabilization of genetic material and mechanisms enhancing mutagenesis, bacterial genome rearrangements, and horizontal gene transfer, induced by oxidative damage to cell components are also considered. Based on the analysis of publications, it can be claimed that rapid development of new food substrates and ecological niches by microorganisms occurs due to acceleration of genetic changes induced by oxidative stress, mediated by several stress regulons (SOS, RpoS and RpoE) and under selective pressure. The authors conclude that non-lethal oxidative stress is probably-one of the fundamental processes that guide evolution of prokaryotes and a powerful universal trigger for adaptive destabilization of bacterial genome under changing environmental conditions.
The influence of anthropogenic pollution, particularly with polycyclic aromatic hydrocarbons (PAHs) on soil toxicity and spread of antibiotic resistance genes (ARGs) is extremely important nowadays. ...We studied 20 soil samples from a technogenically polluted site, municipal solid wastes (MSW) landfills, and rural settlements in the southwestern part of the Rostov Region of Russia. A close correlation was established between the results of biosensor testing for integral toxicity, the content of genes for the biodegradation of hydrocarbons, and the concentration of PAHs in soils. The relation between the quantitative content of ARGs and the qualitative and quantitative composition of PAHs has not been registered. Soils subjected to different types of the anthropogenic pressure differed in PAHs composition. The technogenic soils are the most polluted ones. These soils are enriched with 5 ring PAHs and carry the maximum variety of assayed ARGs, despite the fact that they do not receive household or medical waste.
•At biotesting soils contaminated with industrial PAHs are more toxic than landfills.•Technogenically polluted soils are enriched with 5 ringPAHs compared to landfills.•Technogenically polluted soils contain more diverse ARGs.
Antibiotics are widely used in animal husbandry at present. Due to their excessive and incorrect use, they have led to the rapid spread of antibiotic resistance genes (ARGs), as well as ...antibiotic-resistant bacteria (ARB) in microbial communities of the environment. The review examines works on the use of antibiotics in animal husbandry, the transmission of ARGs and ARB from animals to humans, their spread in the environment with wastewater from livestock enterprises and water and air flows. The role of manure as a reservoir of ARGs and the effect of the processing and storage of manure on the abundance and diversity of ARB and ARGs have been also analyzed. We have also touched on issues related to the presence of ARGs and ARB in animal and plant products and their introduction into the human microbiome with food.
•The high content of pollutants negatively affects bacterial biodiversity.•The structure of soil microbiome depends on the pollutant type.•Pollutants have diverse effects on different bacterial taxa.
...Metagenomic studies of soil microbocenoses are extremely relevant nowadays. The study of pollution impact on soil microbiomes is of particular interest. The structure of microbial communities in soils with different levels of pollution by polycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs) was studied. High bacterial biodiversity was found in all the studied soil samples, but its lowest values are found in soil samples taken on the territory of technogenically polluted Lake Atamanskoye. Assessment of soil pollution showed the highest content of polycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs) for the soils Lake Atamanskoye. The high content of pollutants negatively affects the abundance of representatives of the phyla Actinobacteria, Planctomycetes, Verrucomicrobia, and Nitrospirae. Such phyla as Proteobacteria, Candidate Divisions TM7, OD1, WPS-2, Chlamydiae, Cyanobacteria are characterized by positive direct correlation with the content of pollutants, especially with PAHs. A cooperative effect of decrease in the number of Actinobacteria and Proteobacteria with an increase in Armatimonadetes probably corresponds to PTEs contamination. The proportion of Candidate Division OD1, Chlamydiae, Cyanobacteria, and Candidate Division WPS-2 was increased in the soil microbiome under the influence of severe combined pollution. Pollutants negatively affect the abundance of dominant unclassified_o__Gaiellales and unclassified_o__WD2101 genera. Iamia, Salinibacterium, Arthrobacter, Kaistobacter, Thiobacillus genera are characterized by a low abundance, but they are presumably the most resistant to soil pollution. It was revealed that the level of soil pollution largely determines the composition and diversity of bacterial communities in the soils of the studied territories. Operating taxonomic units have been established that have prognostic value for assessing the state, level of soil pollution, and their biological safety.
In this work, the effect of low-molecular-weight polycyclic aromatic hydrocarbons (PAHs), naphthalene and anthracene, on the formation of biofilms by the strains of
Acinetobacter calcoaceticus
VKPM ...B-10353,
Pseudomonas putida
, and
Vibrio aquamarinus
VKPM B-11245 has been studied. The intensity of biofilm formation (staining with crystal violet), the number of viable cells (staining with fluorescein diacetate), as well as the metabolic activity of microbial cells included in biofilms (XTT-assay) were assessed. It was found that the studied strains are characterized by different responses to the introduction of pollutants. The
V. aquamarinus
VKPM B-11245 strain mainly showed a protective reaction; in the presence of the studied PAHs, an increase in the total bacterial biofilm biomass was observed, as well as a decrease in the number of living cells and the level of cellular metabolism. The naphthalene concentrations of 0.1 and 0.2% caused a reduction of all studied indicators. The
P. putida
strain is the most resistant to the action of the tested PAHs: in the presence of naphthalene, an increase in both the total biofilm mass and cellular metabolism was observed. Anthracene enhanced cellular metabolism in this strain, which allows considering the studied
P. putida
strain as potentially useful for bioremediation. The
A. calcoaceticus
VKPM B-10353 strain was highly sensitive to naphthalene, which was expressed in the suppression of biofilm formation and a decrease in cellular metabolism at all studied concentrations. However, anthracene caused a growth of biofilm mass and enhanced its metabolism, which may indicate the potential ability of the
A. calcoaceticus
VKPM B-10353 strain to degrade this PAH.
This review considers papers on the diversity of the structure and functions of prokaryotic peroxidases. The most significant groups of peroxidases found in bacteria, such as catalases (Kats), ...catalase peroxidases (CPs), di-heme cytochrome c peroxidases (DiHCcPs), dye-decolorizing peroxidases (DyPs), are described. The data on their use in biotechnology are presented. Their participation in the biodegradation of recalcitrant substrates by microorganisms and the possibility of their use in bioremediation are discussed.
The level of catalase and superoxide dismutase induction, as well as generation of superoxide anion radical in cells and accumulation of hydrogen peroxide in the culture medium were researched in ...three strains of oil-degrading bacteria
Achromobacter xylosoxidans
at cultivation in rich nutrient medium and in the media with hydrocarbons as the only source of carbon. The effects of pentane, decane, hexadecane, cyclohexane, benzene, naphthalene and diesel fuel were evaluated. It was determined that in the microbial cell on media with hydrocarbons, the generation of superoxide anion radical increases, accumulation of hydrogen peroxide and induction of superoxide dismutase synthesis occur, and catalase activity is reduced. Oxidative stress in the cells of
A. xylosoxidans
was caused by biotransformation of all the studied hydrocarbons. The most pronounced effect was observed at incubation of bacteria with cyclohexane, pentane, diesel fuel, benzene and naphthalene.
In this work, oxidative damage and the level of antioxidant response in
Acinetobacter calcoaceticus
,
Pseudomonas putida
, and
Rhodococcus erythropolis
cells under the influence of such antibiotics ...as ampicillin, azithromycin, rifampicin, tetracycline, and ceftriaxone were studied. The level of protein carboxylation and lipid peroxidation (LPO), as well as the activity of superoxide dismutase (SOD), catalase, glutathione reductase (GR), and the level of glutathione 3 and 6 hours after antibiotic treatment of bacteria were assessed. It is observed that SOD induction occurs earlier and is more active than catalase induction. In
A. calcoaceticus
, SOD is induced together with protein carboxylation and probably protects them from oxidative damage, while catalase induction correlates with LPO. A positive correlation is also noted between catalase activity and glutathione content in
R. erythropolis
. Catalase activity increases insignificantly and even decreases under the studied antibiotics influence, which is associated with an insignificant level of lipid peroxidation in most prokaryotes. On the other hand, low catalase activity can contribute to genome destabilization as a result of oxidative stress and enhance the adaptive evolution of bacteria.
The qualitative and quantitative composition of polycyclic aromatic hydrocarbons (PAHs) pollutants at 13 points of the impact zone of the Novocherkassk thermal electric power plant (NchPP) has been ...determined. This territory has been polluted with emissions from brown coal combustion for several decades. A total of 200 isolates from PAH-degrading bacteria were selected from the soils and surface sediments, heavily contaminated with PAHs. Taxonomic identification of isolates was carried out by sequencing of the 16S rRNA genes and by MALDI-TOF analysis of protein spectra. Soil cultivable PAH-degrading microorganisms were represented by six species of four genera of actinobacteria (
Arthrobacter
,
Rhodococcus
,
Oerskovia
and
Isoptericola
). Surface sediments cultivable PAH degraders were represented by six species of the genus
Pseudomonas
.
R. erythropolis
was the most numerous of soil isolated strains. The studied soils heavily contaminated with PAHs display low biodiversity of cultivable PAH-degrading bacteria and do not have a connection between the quantity of PAHs in the soil samples and taxonomic variety of PAH degraders. Cultivable PAH degraders were represented in the soils exclusively by Gram-positive bacteria, and in the surface sediments only by Gram-negative bacteria.
Prokaryotic cytochromes P450 (Review) Khmelevtsova, L. E.; Sazykin, I. S.; Sazykina, M. A. ...
Applied biochemistry and microbiology,
07/2017, Letnik:
53, Številka:
4
Journal Article
Recenzirano
The research on the structure and role of bacterial cytochromes P450 are summarized in this review. We consider the organizational features of these enzymes, cytochrome-catalyzed reactions, the ...distribution of cytochromes among prokaryotes, and their functions in bacterial cells. We cite the data on cytochrome genes and the regulation of their expression in prokaryotes and classify cytochromes by components involved in the electronic transition. We consider the role of bacterial cytochromes in the biodegradation of carbohydrates and xenobiotics by microorganisms and the possible involvement of reactive oxygen species, which are generated in the catalytic cycle of these enzymes, at the initial stages of carbohydrate biodegradation.
