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 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.
Microbial communities of the Arctic Ocean are poorly described in comparison to aquatic environments of other regions regarding their patterns of distribution and change. The present work aims to ...investigate free-living bacterial communities (size fraction 0.22–1.5 μm) of different Arctic seas regions, from the river discharge area to the continental slope. Illumina MiSeq metabarcoding analysis using V3–V4 region of 16S rRNA gene was employed to study the microbial diversity of 11 Arctic seawater samples, collected from the surface and near-bottom layers in the Kara and Laptev Seas in August–September 2018. Additionally, we determined environmental parameters, bacterial abundance, biomass, and respiratory activity. Redundancy analysis, Spearman’s rank correlation, and multiple linear regression analysis were used to reveal environmental factors that modulate the bacterial community structure. The differences in the free-living bacterial community composition were associated with environmental characteristics of water layers (salinity and temperature) rather than with geographical area. Although the communities from all examined sites were dominated by
Gammaproteobacteria
and
Alphaproteobacteria
followed by
Flavobacteriia
and
Actinobacteria
, they showed distinct variations in the distribution at all taxonomical levels. No archaeal taxa were observed. The distribution patterns of the quantitative parameters of total bacterial community were not associated with defined environmental characteristics.
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.
Kinetic parameters (rate constants, energies and entropies of activation) of the acid-catalytic hydrolysis of reducing disaccharides cellobiose and lactose are determined in a wide range of mixtures ...of water and organic solvents (dioxane, acetone, DMSO, and acetic acid). It is shown that raising the content of the organic solvent accelerates the hydrolysis of the glycosidic bonds in different ways. The effect solvents have on the rate and mechanism of the studied reaction is discussed on the basis of solvation concepts.
—The paper discusses the spatial distribution of the main parameters of primary production in the Bransfield Strait in the austral summer. The integrated primary production in the strait varied from ...435 to 741 mgC m
–2
day
–1
. The share of primary production in the total production of phyto- and bacterioplankton in the upper 10 m layer was 82–91%. Potential photosynthetic capacity (F
v
/F
m
) was high within the euphotic layer (0.418–0.749) throughout the area. The production parameters in the two main water masses in the strait did not differ. Photosynthetic efficiency (the ratio of the assimilation number and the relative electron transport rate, AN/rETR) varied in different subregions of the study area by almost six times.
—The article studies the abiotic characteristics in waters of the Bransfield Strait in January 2022. The cross-section of January 2020 was repeated from the Antarctic Peninsula to the Southern ...Shetland Islands; new data were also obtained: two cross-sections in the eastern and western parts of the strait. The scheme of currents in the Strait reflects modern knowledge; absolute values have been measured up to 50 cm/s in the northeast direction and up to 35 cm/s in the southwest. In the studied area, modified waters of the Bellingshausen Sea are clearly distinguished (warm and least saline, with reduced values of total alkalinity and all nutrients); modified Weddell Sea water (colder and more saline, with reduced values of silicates and nitrates), as well as Circumpolar Deep Water in the 200–450 m layer (warm and salty, with low values of dissolved oxygen and pH and increased content of phosphates, silicates. and nitrates). In bottom waters of the strait, there were no serious changes in structure. The amplitude of the interannual variability of the abiotic characteristics of Bransfield Strait waters is poorly expressed, nevertheless it can serve as a climate change marker in the Southern Ocean.
—In January–February 2022, a CTD/LADCP section with hydrochemical observations was made across the Powell Basin in the Weddell Sea on an Antarctic expedition of the R/V
Akademik Mstislav Keldysh
. ...The section extended from the Antarctic Peninsula to the South Orkney Islands; thus, it crossed the Weddell Gyre in its northwestern part. As a result, new data were acquired on the hydrological and hydrochemical structures and water dynamics in this region. This study presents new results on analysis of data related to the structure of the Weddell Gyre, formation of Antarctic Bottom Water, and variability of hydrophysical and hydrochemical characteristics of water in the Powell Basin. Only two of the three currents were identified in the structure of the Weddell Gyre: the Antarctic Coastal Current and Antarctic Slope Front,. The velocities of these currents were about 10–15 cm/s. The structure of waters was typical of the Weddell Sea, but a change in the temperature maximum was recorded in the Warm Deep Water layer.
The present study examined the hydrochemical and biological parameters influencing the spatial distribution of bacterioplankton in the Laptev Sea and the East Siberian Sea shelf regions affected by ...the Khatanga, Indigirka and Kolyma rivers runoff during September 2017. The highest bacterial abundance and the amount of actively respiring bacteria were determined in rivers delta and in surface water along the edge of continental shelf. Despite the expectations based on previous studies salinity was not the determining factor affecting spatial distribution and activity of bacterioplankton. Bacterial abundance and biomass were significantly and positively correlated with chlorophyll “a” and pheophytin content.
Kinetic parameters (rate constant, energy of activation, and entropy of activation) of the acid-catalyzed hydrolysis of the benzyl ethers (3,4-dimethoxyphenyl)-(2-methoxyphenoxy)methane and ...(4-hydroxy-3-methoxyphenyl)methoxymethane are determined for a wide range of compositions for mixtures of water and organic solvents (dioxane, DMSO, and acetic acid). It is shown that the acid-catalyzed hydrolysis of these benzyl ethers in mixtures of water and aprotic solvents occurs as a reaction of bimolecular nucleophilic substitution. In aqueous acetic acid solutions, the mechanism of hydrolysis can be bimolecular or unimolecular, depending on the structure of the ether and the content of the organic solvent. The effect the solvents have on the rate and mechanism of the studied reaction is discussed in terms of solvation concepts.
