Number Of Soil Microorganisms Research Articles

Influence of firefighting fluorosynthetic film forming foam on soil microbocenosis

Per- and polyfluoroalkyl substances (PFASs) are a group of over 5000 different chemicals that are used in a wide range of industrial applications and consumer products. Perfluoroalkyl substances have unique properties, such as high chemical stability and surface activity, which leads to their widespread use in medicine, science and everyday life. Aqueous film forming foams (AFFFs) are complex proprietary formulations that contain percent levels of PFASs as well as solvents and hydrocarbon surfactants which, when combined, afford AFFF the functionality required for its purpose. Firefighting foams, such as AFFF, are used primarily to control fires involving flammable liquids such as fuel and oil. AFFF suppresses fire by producing a film over the fuel/oil fire that effectively starves the fire of oxygen. The carbon-fluorine bond makes these compounds extremely strong and stable. This chemical and thermal stability allows these substances to persist in the environment without breaking down. While biological effects of single PFAS have been studied, the effects of PFAS-containing mixtures, such as AFFF, are unknown. The environmental effects of firefighting foam pollutants are generally considered in terms of their toxicity and their biodegradability. Firefighting foams have been found to have a negative impact on the environment (e.g. can remove oxygen from aquatic environment in turn killing aquatic fauna). The effect of PFAS on the microorganisms is not sufficiently studied. To date, there are few studies on the structure and dynamics of microbes in the presence of per- and polyfluoroalkyl substances. Moreover, the results are contradictory. In this regard, it is important to study the impact of various PFAS chemicals on the microorganisms. The article presents the results of the effect study of a fluorosynthetic film forming foam, the main component of which is perfluorinated organic acid, on soil microorganisms, namely ammonifiers, oligonitrophils and nitrogen-fixing microorganisms, yeasts and molds, actinobacteria, and cellulose-degrading bacteria. It was accomplished by plating a sample of the soil that has been serially diluted in water and enumeration of colony forming units (CFU) per gram of soil. The number of soil microorganisms was counted two weeks and three months after contamination with a fluorosynthetic film forming foam. The control sample was unpolluted soil. The sample of soil (1.0 g) was mixed and suspended with a 10 ml of water in a tube for isolation and enumeration of microorganisms. The sample was shaken vigorously to separate organisms from the colloidal material surrounding soil particles. Obtained suspension was serially diluted from 10-2 to 10-6. Aliquot of each dilution was plated onto suitable agar medium. Meat-peptone agar, wort agar, starch-ammonia agar, ashby's agar and hutchinson's agar were used to isolate different groups of microorganisms from gray forest soil and to study the effect of film forming foam on them. The plates were incubated at 28 °C for 3–14 days and the results are expressed as CFU per gram of soil. Colonies of bacteria on meat-peptone agar and ashby's medium were counted after 3–4 days, yeasts and fungi on wort agar after 4–5 days and actinobacteria on starch-ammonia medium after 7–10 days. The number of colonies of cellulose-degrading microorganisms was counted after 14 days cultivation. Firefighting fluorosynthetic film forming foam led to the soil microbial community restructuring and a microbial diversity decrease. The study revealed a decrease the number of different groups of soil microorganisms two weeks after the pollution with the firefighting fluorosynthetic film forming foam, in particular ammonifiers by 2 times compared to the control, nitrogen-fixing microorganisms by 2.7 times, actinobacteria by 4.7 times, yeasts and fungi by 2.8 times. Three months after soil contamination with AFFF the number of nitrogen-fixing microorganisms, actinobacteria, yeasts and fungi increased by 1.85, 1.2 and 2.6 times compared to the control respectively. The number of ammonifiers and cellulose-degrading microorganisms decreased by 1.7 and 5.0 times compared to the control respectively.

Effect of continuous planting on Casuarina equisetifolia rhizosphere soil physicochemical indexes, microbial functional diversity and metabolites.

Continuous planting has a severe impact on the growth of Casuarina equisetifolia. In this study, the effects of three different long-term monocultures (one, two and three replanting) on the physicochemical indexes, microbial functional diversity, and soil metabolomics were analyzed in C. equisetifolia rhizosphere soil. The results showed that rhizosphere soil organic matter content, cation exchange capacity, total and available nitrogen, total and available phosphorus, and total and available potassium contents significantly decreased with the increasing number of continuous plantings. The evaluation of microbial functional diversity revealed a reduction in the number of soil microorganisms that rely on carbohydrates for carbon sources and an increase in soil microorganisms that used phenolic acid, carboxylic acid, fatty acid, and amines as carbon sources. Soil metabolomics analysis showed a significant decrease in soil carbohydrate content and a significant accumulation of autotoxic acid, amine, and lipid in the C. equisetifolia rhizosphere soil. Consequently, the growth of C. equisetifolia could hinder total nutrient content and their availability. Thus, valuable insights for managing the cultivation of C. equisetifolia and soil remediation were provided.

Enhancing lead removal from wastewater and alleviating lead stress in soil-wheat systems using starch-stabilized Fe-Ni/biochar composites: Synthesis and physico-chemical investigations

In this study, starch-stabilized and Fe/Ni bimetal modified biochar composites of StFeNi-BC and StFeNi-BC-350 were successfully fabricated and applied in removing Pb(II) from aqueous solutions. The absorption of Pb(II) by StFeNi-BC and StFeNi-BC-350 were controlled by monolayer chemisorption and their maximum adsorption capacities were 122.767 and 148.043 mg/g, respectively. Mechanism studies showed that electrostatic attraction, ion exchange, complexation and physical adsorption occurred on the adsorbent surface. Studies on the influence of co-existing metal ions and water matrices on adsorption of Pb(II) demonstrated that StFeNi-BC-350 displayed high anti-interfering ability and promising application prospect for Pb(II) removal. In addition, StFeNi-BC-350 was applied in soil-wheat pot systems to further investigate its influence on reducing Pb induced oxidative stress on wheat. Compared with the control, the addition of StFeNi-BC-350 increased the biomass and total chlorophyll content in leaves, and decreased the activity of antioxidant enzymes (MDA, SOD, CAT, POD) together with ROS fluorescence intensity of wheat. The results indicated that StFeNi-BC-350 could alleviate Pb(II) stress of wheat. Furthermore, the addition of StFeNi-BC-350 improved the physicochemical properties of the soil, and increased the abundance as well as the number of soil microorganisms, thereby alleviating Pb stress on wheat. Therefore, StFeNi-BC-350 is suitable for the practical treatment of Pb-contaminated water and soil.

Microbiocenosis of Cryofrost Soils in the South of the Vitim Plateau

The microbial communities in soils of cryomorphoses in the south of the Vitim Plateau have been studied. The objects of study were gley cryoturbated chernozems and humus-quasi-gley carbonated soils. In the course of the study, experimental sites with pronounced cryogenic phenomena were selected. The intensity of microbiological activity was determined by the carbon content of microbial biomass, the number of microorganisms in the dominant groups of microbial communities. Determination of the number of microorganisms in soils was carried out by direct microscopy, which makes it possible to carry out a more accurate count of bacteria in the soil, taking into account adsorbed cells. Cells were preliminarily desorbed on an ultrasonic disperser. The carbon of microbial biomass was determined by the rehydration method. Data were obtained characterizing the direction and intensity of microbiological processes along the horizons of soil profiles of heaving mounds and thermokarst depressions. The number of microorganisms and the dominant groups of bacterial communities of soils formed under the conditions of the ultracontinental climate of Buryatia and relatively close-lying permafrost are presented. It was revealed that bacterial microflora predominates in the soils of heaving mounds and thermokarst depressions. The intra-profile heterogeneity in the distribution of soil microorganisms indicates that, as a habitat, the soil is strongly differentiated in all directions. This differentiation along the vertical of heaving mound and thermokarst depression was reflected in the concept of soil horizons as special ecological niches and the possibility of using microbiological indications of heaving and subsidence occurring during heaving.

Effect of γ-PGA and γ-PGA SAP on soil microenvironment and the yield of winter wheat.

Agricultural poly-γ-glutamic acid (γ-PGA) and γ-PGA super absorbent polymer (SAP) are two forms of γ-PGA applied in agriculture. Different quantities of γ-PGA and γ-PGA SAP (40 kg/hm2, 80 kg/hm2, 120 kg/hm2 and 160 kg/hm2) were applied to the soil in order to investigate their effects on the microenvironment of soil root zone and the yield of winter wheat. The soil water content increased with increasing amounts of γ-PGA SAP. The content of nitrate nitrogen and ammonium nitrogen increased with the increasing amounts of γ-PGA, while γ-PGA SAP significantly increased the content of ammonium nitrogen. The number of soil microorganisms and soil enzyme activities in the root zone increased with the addition of γ-PGA and γ-PGA SAP. The yield of winter wheat increased with the addition of γ-PGA or γ-PGA SAP, but the increasing rate decreased when the amount of γ-PGA and γ-PGA SAP exceeded 80 kg/hm2, with increases of 5.95% and 6.77% compared to the control group, respectively. The addition of γ-PGA significantly increased the protein content of wheat grains, and the WUE increased with increasing amounts of γ-PGA and γ-PGA SAP.

Effects of Intercropping Aromatic Plants on the Soil Microbiota in Tobacco Field

By utilising high-throughput sequencing technology, we systematically analysed microbial flora changes in tobacco fields intercropping various Lamiaceae plants that are cultivated mainly for extracting the aromatic compounds. The results showed that the number of soil microorganisms in the rhizosphere changed during the resettling, flourishing, and harvesting periods. Among these periods, the number of actinomycetes in the flourishing period increased, which played a role in enhancing the disease resistance of tobacco plants to a certain extent. The soil microbial diversity analyses revealed that the amount, species and Alpha diversity index of rhizosphere soil microbes were the highest at the resettling and flourishing stages. Bacterial floras belonging toActinobacteria, Firmicutes, Proteobacteria and Nitrospiraewere the dominant ones, playing a certain role in the soil nitrogen cycle and supply. For both bacteria or and fungi, the difference between communities of the soils with the intercropping pattern was greater than that of the control. Bangladesh J. Bot. 51(4): 829-838, 2022 (December) Special

CELLULOSE DESTRUCTIVE ACTIVITY OF SOIL MICROFLORA AT THE INFLUENCE OF DIFFERENT RADIONUCLIDE CONTAMINATION LEVELS

The results on impact of different levels of soil radionuclide contamination on microbiota and cellulosedestroying microflora obtained. The state of this microflora is one of the indicators of the overall soil microbial activity. In the remote period after Chernobyl accident, there is a problem of the agricultural use of radionuclide contaminated territories and returning to economic activity the lands that withdrawn from circulation in 1991-1996. We used the following research methods - spectrometric, radiochemical analysis, microbiological, agrochemical and statistical analysis. For field research in the zone of unconditional (compulsory) resettlement and exclusion zone of the Chernobyl NPP, two sites selected and inspected, within which the burial places for plant material identified and soil samples took for radiological and agrochemical analysis. For sites, a significant gradient in radiological parameters observed. The radiation background varies from 0.13±0.01 to 34.8±0.5 μSv/h. The radionuclides activity concentrations in the soil of sites is characterized by the following parameters: 137Cs - from 600±45 to 203800±4100 Bq/kg, 90Sr - from 33±4 to up to 34000±300 Bq/kg. The absorbed dose rate for microbiota showed maximum values up to 1.57 μGy/h at the 1st site and up to 84.00 μGy/h at the 2nd site. Data on cellulosolytic activity of soil microorganisms of both sites were obtained, TВI index coefficients were calculated and the number of soil microorganisms was estimated based on the results of sowing soil suspension on nutrient media.

Агрегатування сільськогосподарської техніки — одна з сучасних актуальних проблем землеробської механіки

Goal. To determine the formation of symbioticand photosynthetic apparatus, soil microbiota, andseed productivity of soybean varieties of differentprecociousness after seed inoculation with noduleand endophytic bacteria under irrigation conditionsof the Southern Steppe of Ukraine. Methods. Field(determination of the number of nodules on plantroots, total leaf surface, photosynthesis efficiency,soy seed productivity), laboratory (number of soilmicroorganisms), statistical. Results. On average,over 3 years of research (2018–2020), the leafsurface area after endophytic rhizobial inoculationof seeds with RyzobinK + Bacillus sp. 4 was greaterby 63.8–52.6% compared to non-inoculatedplants. In the root zone of plants, the developmentof pedo-trophic, proto-trophic, oligo-nitrogen-trophic,and nitrogen-fixing microorganisms was activatedduring complex endophyte-rhizobial inoculation.Complex inoculation of soy seeds stimulated theformation of a symbiotic system, the number ofnodules increased by 60–65%, and their weight —by 12–51%. In an average of 3 years, during thepre-sowing treatment of seeds with RyzobinK ++ Bacillus sp. 4, the highest yield of soy seeds ofDiona was 2.66 t/ha, and Aratta variety — was2.90 t/ha. Conclusions. The use of nodule andendophytic soy bacteria for complex inoculationof seeds of the ultra-early variety Diona and themid-early variety Aratta contributes to the active developmentof plants with an increased leaf surfaceand high photo assimilation productivity, stimulatesthe growth of agronomically useful soil microorganisms.The highest yield of soybean seeds wasformed by the pre-sowing treatment of seeds withRyzobinK + Bacillus sp.4 and was 28.5–31.8% higherthan in the control variants.

Wheat straw biochar and its performance in treatment of phenanthrene containing water and microbial remediation of phenanthrene contaminated soil

In recent years, biochar has been considered as an effective adsorbent and soil conditioner due to its abundant carbon and high porosity. This study applied a kind of biochar from wheat straw pyrolysis to remediate phenanthrene-contaminated water and soil. The performance of the biochar in the removal of phenanthrene was discussed by liquid phase adsorption and soil incubation experiments. Furthermore, this work explored the enhancement effect of wheat straw biochar on soil microbial numbers and soil properties. The result of liquid phase adsorption indicated, 92.2% of phenanthrene was removed after incubating 0.6 g/L of wheat straw biochar for 4 h. Pseudo-second-order kinetic model (R2 = 0.99823) and Langmuir isotherm model (R2 = 0.99577) described the removal of phenanthrene by wheat straw biochar well. In soil incubation experiment with an initial phenanthrene content of 11.2 mg/kg, 89.1% of phenanthrene was removed at biochar dosage of 12% (w/w, wheat straw biochar/soil) after 30 days of incubation. In addition, the number of soil microorganisms, soil pH and organic matter (SOM) content increased after wheat straw biochar treatment. At the dosage of 12%, soil microbial count increased to 9.8 × 108 CFU/g-soil, soil pH increased by 1.8 units and SOM increased by 8.5 folds. The addition of wheat straw biochar not only improved soil quality, but also reduced the proportion of phenanthrene components, which could provide theoretical support for the resource utilization of agricultural waste.

Phytoremediation potential of rapeseed in phenanthrene‐contaminated soils under different irrigation regimes and pumice levels

AbstractTo evaluate the effects of irrigation regimes and pumice levels on the physiological parameters of rapeseed (Brassica napus) and phenanthrene phytoremediation efficiency, a 15‐week pot experiment was conducted in the open environment of the College of Agriculture at Fasa University. Three irrigation levels, 75%, 100% and 125% of the field capacity, I1, I2 and I3, respectively, and three pumice levels, 0%, 5% and 10% w/w soil, P0, P1 and P2, respectively, were considered. The results showed that the shoot fresh weight, shoot dry weight, shoot‐root ratio, root fresh weight, root dry weight, root volume, root length, root surface area and root length density in the I3P2 treatment increased by 25%, 35%, 22%, 35%, 19%, 24%, 19%, 21% and 19%, respectively, compared to the corresponding control (I2P0). A significant increase in the number of soil microorganisms (32%) and removal of phenanthrene (74%) were achieved in I3P2 compared to I2P0. According to the Pearson correlation coefficient, all physiological parameters of rapeseed had a high negative correlation with the residual phenanthrene in the soil and consequently increased its dissipation. Therefore, the rapeseed plant can be used as a practical and effective species for the phytoremediation of phenanthrene‐contaminated sites.

Influence of Organomineral Fertiliser from Sewage Sludge on Soil Microbiome and Physiological Parameters of Maize (Zea mays L.)

The use of a soil fertiliser results in high, good quality yields. The most widely used fertilisers are mineral or organic, but there is increasing attention on organomineral fertilisers produced from sewage sludge. These contain beneficial components which may improve soil fertility and thus plant productivity, but there are some concerns associated with their application due to their composition. Using a short-term pot experiment the effect of such a soil conditioner called FS, produced from sewage sludge after stabilisation with lime, on the qualitative−quantitative composition and activity of soil microorganisms and selected physiological parameters of the maize was analysed. The study was carried out in a completely randomised design, including a control (soil + lime + NPK). The application of the FS had a positive effect on the soil pH, equivalent to the application of lime. Organomineral fertiliser, as a source of organic carbon and macroelements, had a positive effect on the number of soil microorganisms and their activity, and this influence was stable during maize vegetation. FS did not influence the gas exchange activity of maize, the content of assimilation pigments in leaves or and the efficiency of the photosynthetic apparatus determined by chlorophyll “a” fluorescence analysis, but it increased the light absorption efficiency of the PSII photosystem. Differences in biomass yield from organomineral and mineral fertilisation were statistically insignificant.

Soil microorganisms in the urban ecosystems of the russian subarctic (Murmansk region, Apatity)

A comprehensive study of the quantitative and qualitative parameters of soil microfungi, bacteria and algae communities in the Apatity city, located in the subarctic zone of Russia, was carried out for the first time. Urban soil samples were taken from various landuse zones (residential, recreational) and compared to arable and forest soils. In the residential zone, a decrease in the number of microfungi in the topsoil horizon to 1.1 thous. CFU/g compared to 22.7 thous. CFU/g in forest soil was revealed. In the residential zone, an increase was found in the number of saprotrophic bacteria to 7.8 million cells g-1 and oligotrophic to 10.9 million cells g-1 compared to 2.6 million cells g-1 and 1.8 million cells g-1 respectively in forest soils. In the recreational zone, the number of soil microorganisms was similar to that in the forest. A decrease in the species diversity of microfungi in the soil of the residential zone and an increase in the diversity of soil algae were revealed. Among the dominant species of fungi in urban soils, atypical species, including pathogenic ones for humans (Penicillium dierckxii, Stachybotris echinatus, Fusarium sp.), were found. In the algal community, diatoms, yellow-green algae, and cyanobacteria appeared in urban soils in comparison with forest soil. As a result of changes in the quantitative and qualitative indicators of soil microbial communities, a decrease in the enzymatic activity of soils has been noted. This may indicate a weakening of the ecosystem functions of urban soils and an increase in the degree of toxicity for living organisms and humans.

Binary plantings as a factor of reducing the technogenic load of agrocenosis

The results of research conducted by Voronezh State Agrarian University to determine the effect of binary sunflower plantings in combination with postharvest sideration on the content of plant residues in the soil, on the number of soil microorganisms, on the dynamics of detritus, sunflower infestation and yield are presented. The positive effects of the studied complex of biological function was well established to increase the content of organic matter sources in soil (by 4.64 of 5.67 t/ha), contributing to the increase in the content in the soil detritus (4.7 and 9.9%) on the growth of soil microorganisms, which in combination with the reduction of planting infestation (by 9-18 pcs/m2) has led to significantly higher yields of sunflower (0.18-0.51 in t/ha) compared with the traditional technology of cultivation. As binary components of sunflower, it is recommended to use perennial legumes of yellow melilot and purple alfalfa, and oil radish as a postharvest sideral crop.

Effect of Tillage System and Organic Matter Management Interactions on Soil Chemical Properties and Biological Activity in a Spring Wheat Short-Time Cultivation

Properly selected tillage methods and management of the available organic matter resources are considered important measures to enable farming in accordance with the principles of sustainable agriculture. Depending on the depth and intensity of cultivation, tillage practices affect soil chemical composition, structure and biological activity. The three-year experiment was performed on the soil under spring wheat (cv. Tybalt) short-time cultivation. The influence of different tillage systems and stubble management on the soil’s chemical and biological parameters was analyzed. Organic carbon content (OC); content of biologically available phosphorus (Pa), potassium (Ka), and magnesium (Mg); content of total nitrogen (TN), mineral nitrogen forms: N-NO3 and N-NH4 were determined in various soil samples. Moreover, the total number of microorganisms (TNM), bacteria (B), actinobacteria (A), fungi (F); soil respiratory activity (SR); and pH in 1 M KCl (pH) were also investigated. The results show that organic matter amendment is of greater influence on soil characteristics than the tillage system applied. Manure application, as well as leaving the straw in the field, resulted in higher amounts of organic carbon and biologically available potassium. A significant increase in the number of soil microorganisms was also observed in soil samples from the experimental plots including this procedure.

Selective influence of cyflumetofen in degradation and ecological risk assessment

AbstractPesticide pollution has gradually caused land degradation. In order to avoid this problem, it is recommended to use enantiomeric pesticides that have less impact on the soil. Cyflumetofen's (CYF) microecological environmental assessment at the enantiomer level is unclear. In our study, the degradation of CYF enantiomers and the effect on soil functions are closely related to microorganisms. (+)‐CYF enantiomer is degradable preferred and further discovered that related microorganism that degrades enantiomers. CYF enantiomers alter the bacteria structure and decreased the bacteria abundance. The combination of high‐throughput and quantitative PCR results showed that the diversity of the (+)‐CYF treatment was significantly lower than that of the (−)‐CYF (−30.41 to 44.60) treatment, and the (+)‐CYF treatment (−27.80% to 56.70%) was more capable of causing the decrease in the number of soil microorganisms. In addition, (+)‐CYF severely interferes with nitrogen cycling–related functions. Furthermore, the soil microbial structure was changed to its original level by enantiomers posed. In the study of nitrogen cycle functions, we found that both enantiomers can restrain the abundance of nitrogen cycle–related genes, especially the (+)‐CYF treatment decreased more. Canonical correspondence analysis (CCA) showed that g‐Massilia and g‐Arthrobacter are closely related to nitrogen fixation genes and nitrification genes, and degradation of the two enantiomers of CYF by g‐Arthrobacter is closely related. The biological effects of CYF enantiomers remain unclear. Bioassay results show that enantiomers have similar virulence to Tetranychus cinnabarinus. Therefore, while achieving the prevention and control effect, the use of a single isomer (+)‐CYF has a higher potential risk to the soil ecosystem.

Assessment of the impact wastewater of dairy farms on soil microbiota

In the production of milk on cattle-breeding farms and complexes large amount of wastewater is formed containing significant numbers of chemicals and is ecologically hazardous source of pollution of water and soil resources. Wastewater of dairy farms contain natural animal excretions, exhaust solutions of cleaning and disinfecting agents, milk residue which is washed off from internal surfaces of milking equipment, residues of feed, litter, dirt, which is washed off during washing of walls and floor of dairy cow house. Since such wastewater contain valuable organic substances they are used to fertilize plants. There are technologies of safe use of wastewater from cattle-breeding farms to fertilize pastures. Also wastewater used as fertilizer in cultivation of sugar beets, tomatoes, cucumbers, spinach, cabbage and the like. It is expedient determination of the influence of wastewater used for the fertilizer of agricultural cultures, on the soil microbiota. After all, soil fertility is inextricably linked with microorganisms that inhabit her. The aim of the work was carrying out of an assessment of influence of wastewater from dairy farms on the soil microbiota. Samples of soil for microbiological studies were selected in 20 centimetre thickness of top layer after application of wastewater of dairy farms. The total microorganism number was determined the method of sowing of soil suspension of corresponding dilutions on nutrient medium of meat-and-peptone agar (MPA). Micromycetes on Chapek medium. The state of soil microorganisms after application in her different doses of wastewater of dairy farms was investigated. It is established, that the total number of microorganisms in soil when accounting 12 days later after application of wastewater in quantities of 500 l/ha exceeded control by 7.4%. At doses of 600 l/ha and 700 l/ha by 9.8% and 12.4% accordingly. 30 days later after application of waste-water the number of microorganisms almost did not differ from control. It was observed that after application of wastewater increase the total number of micromycetes. 12 days later after application of dose 500 l/ha, of number of micromycetes was increased on average by 14,6%; in dose of 600 l/ha by 18.0%; in dose of 700 l/ha — by 19.6%. 30 days later after application of wastewater the total number of micromycetes exceeded control by 1.5%. It is defined, that wastewater of dairy farms in doses of 500–700 l/ha do not exert negative effect on soil microbiota.

Features of changes in the number and composition of the microbiome of the rhizosphere of winter wheat in the process of ontogeny

In agroecosystems, microorganisms are the main factor in the soil formation process, plant nutrition and phytosanitary condition of the soil. All measures aimed at restoring soil fertility and increasing productivity, environmental safety of agricultural production, are closely related to the activity of microorganisms. Increased local activity, biomass and diversity of microbiota are one of the most important characteristics that distinguish the rhizosphere from the total soil volume. The purpose of the research was to study the number and composition of the microbial complex of the rhizosphere of grain crops (winter wheat of different varieties of domestic selection) in the process of ontogenesis. To conduct a set of microbiological studies, soil samples (typical chernozem) were selected and prepared in compliance with standard requirements for sample preparation and storage in laboratory conditions. Analysis of rhizosphere soil samples was carried out on variants of different varieties of winter wheat of domestic selection. The number of soil microorganisms was determined by seeding suspensions on nutrient media according to generally accepted methods in microbiology. The determination of the total microbial biomass in the soil was carried out by the rehydration method, and the intensity of soil “breathing”, in terms of CO2 release and O2 absorption, was determined by the manometric method (Warburg apparatus). It was found that winter wheat varieties affected the formation of the microbiome of typical chernozem. The number and composition of the microbial complex of the rhizosphere of winter wheat in the process of ontogenesis changes significantly, especially in terms of the ratio of the number of spore-forming and non-spore forms of microorganisms under the same conditions of agricultural technology for growing crops. The rhizosphere's total pool of saprotrophic microorganisms shows biomass variability and changes in favour of ecoplastic bacilli. An increase in the number of spore-forming bacteria to 4.2 x 107 CFU/g was found in the variants of cultivation of certain varieties. Cultivation of different varieties of winter wheat demonstrates stable indicators of CO2 emission intensity – from 5.2 to 7.0. A similar trend can be traced in the absorption rate of O2 (no more than 5.3-6.8)

Assessment of the State of Soil’s Microbial Community in Condition of Intensive Influence of Pollutants

Abstract This paper presents the study of toxicological state of the soil. It shows ecological and microbiological properties of the soil mantle in the areas of technological environmental impact and evaluates changes in the number of soil microorganisms as a result of toxic contamination of urban soil at different distances from the Moscow loop highway, and also as a result of dumping aluminum foundry slag in Orel region. Soil-inhabiting invertebrates species composition was evaluated at different soil contamination conditions. It was proven that the state of microbiocenosis changes depending on the intensity and character of the anthropogenic impact. It was established that soil fermentation and microbiological activity changes depending on the value of the cumulative heavy metals’ build-up coefficient. Study of interelement ties between the heavy metals concerned showed that they too may have the same anthropogenic origin regardless of their sources of origin. Pollution index indicates medium to high level of soil contamination in explored urban territories where vehicle emission is the main source of pollution, and dangerously high contamination of light-gray soil in the small settlement impacted by a nearby slag disposal site.

Особливості зміни чисельності та складу мікробіому ризосфери пшениці озимої в процесі онтогенезу

In agroecosystems, microorganisms are the main factor in the soil formation process, plant nutrition and phytosanitary condition of the soil. Therefore, all measures aimed at restoring soil fertility and increasing productivity, environmental safety of agricultural production are closely linked to the activities of microorganisms. Increased local activity, biomass and diversity of microbiota are one of the most important characteristics that distinguish the rhizosphere from the total soil volume. The aim of the research was to study the number and composition of the microbial complex of the rhizosphere of cereals (winter wheat of different varieties of domestic selection) in the process of ontogenesis. To conduct a set of microbiological studies, soil samples were taken and prepared (typical chernozem) in compliance with the standard requirements for sample preparation and storage of samples in the laboratory. The analysis of rhizosphere soil samples was performed according to the variants of different varieties of winter wheat of domestic selection. The number of soil microorganisms was determined by the method of inoculation of suspensions on nutrient media according to generally accepted methods in microbiology. Determination of the total microbial biomass in the soil was carried out by the rehydration method, and the intensity of "respiration" of the soil, respectively, by the release of CO2 and O2 absorption by the manometric method (Warburg apparatus). It is established that varietal specificity is significantly related to the peculiarities of microbiome formation in different phases of plant growth and development, which is an integral indicator of functional and metabolic activity of soil microorganisms. The number and composition of the microbial complex of winter wheat rhizosphere in the process of ontogenesis changes significantly, especially in the ratio of the number of spore-forming and non-spore forms of microorganisms under the same conditions of crop cultivation. The total pool of saprotrophic microorganisms of the rhizosphere demonstrates the variability of biomass and changes in favor of ecoplastic Bacillus. An increase in the number of spore-forming bacteria to 4.2 x 107 CFU/g in the variants of growing certain varieties was found. It is shown that in the cultivation of different varieties of winter wheat there are stable indicators of the intensity of CO2 emissions - from 5.2 to 7.0. A similar trend can be traced to the absorption of O2 (not more than 5.3-6.8).

Micro and Macro (Organisms) and Their Contributions to Soil Fertility

Soil chemical properties and microbial populations were always determined in soil in order to compare the contributions of microorganisms to soil fertility and to sustain agricultural plant growth. The ability to supply essential plant nutrients (phosphorus (P), potassium (K), nitrogen (N), sulphur (S) etc.) and soil water in adequate amounts and proportions for plant growth and reproduction; and the absence of toxic substances which may inhibit plant growth. This research work therefore aimed at understanding the different types of microbes present in soil and their various contributions to soil fertility. Sample collection normally ranges from 0-20 cm depth in the soil. These samples were air dried, passed through a 2-mm sieve before soil properties were determined following standard methods. Fresh soil samples were used to determine the number of soil microorganisms via the dilution spread plate technique using the nutrient agar for bacteria and potato dextrose agar for fungi. Research showed that the forest and fallow lands had significantly lower pH value, available P, exchangeable K and Na, but significantly higher exchangeable H and bacteria population than the cultivated land. The mean exchangeable Ca was significantly higher in the cultivated land than in the fallow land but similar to that from the forestland. The fungi population was also higher in the forestland than in others which are similar statistically. The mean soil organic matter, total N, exchangeable Mg, exchangeable Al and CEC were similar in all the land use types. Contributions of microorganisms to soil fertility were generally more in the uncultivated lands, an indication that tillage operations may have affected the microbial populations. Also the relationship between some soil chemical properties and microbial densities signify important roles microorganism play in soil nutrient build up.