Oligotrophic Bacteria Research Articles

Polyphyletic photosynthetic reaction centre genes in oligotrophic marine Gammaproteobacteria

Ecological studies indicate that aerobic anoxygenic phototrophic bacteria (AAP) that use bacteriochlorophyll to support phototrophic electron transport are widely distributed in the oceans. All cultivated marine AAP are alpha-3 and alpha-4 Proteobacteria, but metagenomic evidence indicates that uncultured AAP Gammaproteobacteria are important members of ocean surface microbial communities. Here we report the description of obligately oligotrophic, marine Gammaproteobacteria that have genes for aerobic anoxygenic photosynthesis. Three strains belonging to the OM60 clade were isolated in autoclaved seawater media. Polymerase chain reaction assays for the pufM gene show that these strains contain photosynthetic reaction centre genes. DNA sequencing and phylogenetic analysis indicate that the pufM genes are polyphyletic, suggesting multiple instances of lateral gene transfer. Peptide sequences from six photosynthesis genes (pufL, pufM, pufC, pufB, pufA and puhA) were detected by proteomic analyses of strain HTCC2080 cells grown aerobically in seawater. They closely match predicted peptides from an environmental seawater bacterial artificial chromosome clone of gammaproteobacterial origin, thus identifying the OM60 clade as a significant source of gammaproteobacterial AAP genes in marine systems. The cell yield and rate of growth of HTCC2080 in autoclaved, aerobic seawater increased in the light. These findings identify the OM60 clade as a source of Gammaproteobacteria AAP genes in coastal oceans, and demonstrate that aerobic, anoxygenic photosynthetic metabolism can enhance the productivity of marine oligotrophic bacteria that also grow heterotrophically in darkness.

Isolement et caractérisation de bactéries marines oligotrophes

A significant part of the world ocean is characterized by low absolute nutrients and chlorophyll concentrations. In these oligotrophic environments, bacteria are very abundant and play a vital role in the remineralization of the dissolved organic matter. Bacteria adapted to oligotrophic waters differ from those adapted to richer environments by some genetic and metabolic characteristics. Culture techniques in bacteriology are based on rich media and do not allow the growth of most marine bacteria. New techniques have been developed for the culture of oligotrophic bacteria, which allow to isolate unknown bacteria. Pelagibacter ubique and Sphingopyxis alaskensis belong to these bacteria recently isolated from the marine environment and their study yielded better understanding of how marine bacteria adapt to oligotrophic conditions.

Characterization of Soil Physico-Chemical and Microbial Parameters after Revegetation Near Shaoguan Pb/Zn Smelter, Guangdong, P.R. China

The criterion for judging the successful revegetation largely focuses on the aboveground indicators, whereas the information for soil ecosystem during the revegetation is often ignored. To better understand the effects of the revegetation on the development of the soil ecosystem near Shaoguan Pb/Zn Smelter, Guangdong Province of Southern China, we compared the difference of the microbial and physico-chemical parameters between the four revegetated sites and two control sites (bare ground and native forest area). The soil organic C, total N, total P, NH4-N, NO3-N, available P, WHC and porosity significantly increased and bulk density decreased in the four revegetated sites compared with those in bare ground, indicating the processive effects of the revegetation on the reestablishment of the soil nutrient pools. The heavy metal contents were higher in the four revegetated sites than in the bare ground, thus the revegetation resulted in the accumulation of heavy metals released from smelter in surface soil. The soil microbial composition and activities, except that the oligotrophic bacterial number decreased over revegetation time, significantly increased in the revegetated sites compared with those in the bare ground, and predominantly correlated with soil organic C, total N, NH4-N, NO3-N and WHC. The soil oligotrophic bacteria was negatively related to all individual heavy metal contents, thus was the most sensitive indicator in reflecting heavy metal stress, while other microbial parameters, despite not showing negative relationships to the individual heavy metal contents, were sensitive to the potential availability of Pb and Cu (ratio of available to total heavy metal contents), but less sensitive to those of Zn and Cd. Both the principal component analysis (PCA) and the discriminant analysis (DA) resulted from microbial and physico-chemical datasets not only revealed the shifts of the soil physico-chemical and microbial patterns from the unrevegetated to non-polluted conditions, but also implied the possible loss of effects of revegetation on soil remediation in the sites revegetated for four (RIV) and five (RV) years, respectively.

SOIL MICROBIAL PROPERTIES IN COAL MINE TAILINGS UNDER REHABILITATION

Microbial properties have been reported to be useful indicators of soil quality and could possibly serve as assessment criteria of successful rehabilitation of ecologically disturbed areas. During this study, the application value of microbial enumeration techniques and enzymatic assays as a measure of the progress of rehabilitation of coal discard sites was evaluated. Each site was analysed for physical and chemical characteristics of the topsoil; vegetation cover; potential enzymatic activities (dehydrogenase, s-glucosidase, urease, acid and alkaline phosphatase) and quantification of aerobic oligotrophic and copiotrophic bacteria and fungi (selective enumeration). The relationship between soil properties, vegetation cover and microbial properties was analysed using multivariate ordination techniques. Although the discard sites had different rehabilitation ages (1 - 8 years), no statistically significant difference existed between these sites based on physical and chemical characteristics or selective enumeration (p>0.05). Differentiation was possible based on enzymatic activities, where sites with relatively higher vegetation cover and organic carbon content had a positive association with enzymatic activities. Organic carbon content correlated significantly with β-glucosidase (r = 0.80, p<0.05), urease (r = 0.96, p<0.05), acid phosphatase (r = 0.76, p<0.05), dehydrogenase (r = 0.69, p<0.10) and microbial biomass (r = 0.73, p<0.10). The characterisation of microbial activity holds potential as complementary criteria for evaluating rehabilitation progress on mine discard sites.

Alternation of Factors Affecting Bacterioplankton Abundance in the Danube River Floodplain (Kopački Rit, Croatia)

The purpose of this investigation was to determine the influence of different phases of the hydrological cycle on the abundance of colony-forming units (CFU) of bacteria in the Kopacki Rit floodplain and to assess temporal and spatial variations in the proportion of eutrophic and oligotrophic bacteria (r- and K-strategists) as a biological indicator of dissolved organic carbon (DOC) availability. Determination of bacterial abundance was performed with abiotic variables (water temperature, depth, Secchi disc transparency, dissolved oxygen, pH, electrical conductivity, ammonia, nitrates+nitrites, total nitrogen and total phosphorus) and one biotic (chl-a) variable, and dimensionality reduced with principal component analysis (PCA). The component scores were used as independent variables in a multiple regression and the relationship between scores (indirect variables) and bacterial abundance was examined. An elevated bacterial abundance was observed during the limnophase (floodplain isolated from the river) and potamophase (flood). During the limnophase also the highest chl-a concentrations were found and in Sakadas Lake during September 2003 significantly higher numbers of eutrophic than oligotrophic bacteria emerged (p = 0.026). During potamophase the opposite state was established. Elevated bacterial abundance occurred in parallel with minimal chl-a concentrations and during July 2004 in the Conakut Channel a significantly higher number of oligotrophic than eutrophic bacteria emerged (p < 0.001). Differentiation in the number of eutrophic and oligotrophic bacteria suggests the existence of a higher concentration of labile DOC during September 2003 than during July 2004. Multiple regression analysis explains 13.6% of the variation in abundance of eutrophic bacteria. The regression model for oligotrophic bacteria is not significant. The results suggest two different mechanisms control bacterioplankton numbers to some extent in the Kopacki Rit floodplain. In addition, two sources of DOC differentiating the quality of organic matter predominate under totally different hydrological regimes. Under these conditions, eutrophic bacteria may be partially bottom-up controlled, whereas it is not clear how the abundance of oligotrophs is controlled.

Oscillating dynamics of bacterial populations and their predators in response to fresh organic matter added to soil: The simulation model ‘BACWAVE-WEB’

Recently, regular oscillations in bacterial populations and growth rates of bacterial feeding nematodes (BFN) were shown to occur after addition of fresh organic matter to soil. This paper presents a model developed to investigate potential mechanisms of those oscillations, and whether they were initiated by bacteria–substrate interactions or by predatory regulation of bacteria. The model was also used to investigate mineral nitrogen release during short-term organic matter decomposition. Experimental data originated from several microcosm experiments with a sandy soil amended with clover–grass mixture. Numbers of bacteria and BFN, and nitrate and ammonium content in soil were measured daily during about a month, whereas protozoa were counted occasionally. A substrate-based food web model was constructed with 3 plant residue and 5 soil organic matter compartments, 3 trophic groups of bacteria (copiotrophic, oligotrophic and hydrolytic), and two predatory groups (BFN and protozoa). Both carbon and nitrogen flows between these compartments were modelled. Fluctuations in microbial populations in soil after plant residue incorporation could be reproduced with and without participation of predators. The first two peaks in bacterial numbers were mainly related to bacteria–substrate interactions, while predators (particularly protozoa) influenced bacterial dynamics during later stages of bacterial community development. Oligotrophic bacteria had a stabilizing effect on fluctuations of other trophic groups, and were the main source of nutrients for predators. A peak in soil ammonium occurred within 1 week after residue incorporation. Nitrate increased sigmoidally after a short lag phase. The final nitrate concentration was primarily determined by bacterial dynamics, and to a lesser extent by protozoa and nematodes. This model indicates the importance of substrate–consumer relations for regulation of populations at different trophic levels and nutrient release from fresh organic matter added to soil.

Nutrient and light availability regulate the relative contribution of autotrophs and heterotrophs to respiration in freshwater pelagic ecosystems

In this study, two main hypotheses were addressed. (1) Bacteria contribute proportionally less than autotrophs to ecosystem respiration as trophic status increases. This hypothesis was examined in a pond phosphorus-fertilization experiment and two microcosm nutrient-fertilization experiments. (2) The relative contribution of autotrophs to ecosystem respiration, at a given nutrient availability, increases as light availability increases. This hypothesis was tested in three light by nutrient factorial microcosm experiments. Rates of total plankton community, bacterial ( ,1 mm fraction), and phytoplankton (total 2 bacterial) respiration all increased as nutrient availability increased. The contribution of bacteria to community respiration ranged between ;10 and 90%, with the highest contribution occurring under the most oligotrophic conditions. As light availability increased within each nutrient availability treatment, there was a similar decline in the contribution of bacteria to community respiration. Under oligotrophic conditions bacteria are better competitors for nutrients that limit both autotrophs and heterotrophs, but as nutrient availability increases, conditions become increasingly favorable for larger celled phytoplankton that have higher maximal nutrient uptake rates. As light availability increases, the relative contribution of phytoplankton to ecosystem respiration also increases. Light and nutrient availability are important regulators of the relative contributions of autotrophs and heterotrophs to ecosystem respiration, but the observed patterns are primarily driven by changes in phytoplankton production rates.

RELATION BETWEEN SUPPRESSIVENESS TO TOMATO FUSARIUM WILT AND MICROBIAL POPULATIONS IN DIFFERENT GROWTH MEDIA

RELATION BETWEEN SUPPRESSIVENESS TO TOMATO FUSARIUM WILT AND MICROBIAL POPULATIONS IN DIFFERENT GROWTH MEDIA

DGGE Fragments Oscillate with or Counter to Fluctuations in Cultivable Bacteria Along Wheat Roots

Previously, we showed that bacterial populations oscillate in response to a moving substrate source such as a root tip, resulting in moving wavelike distributions along roots. For this article, we investigated if bacterial communities fluctuate as a whole or if there is a succession in bacterial composition from peak to peak or within peaks. Rhizosphere microbial communities along roots of wheat Triticum aestivum L. were studied in detail (20-25 rhizosphere and bulk soil samples along the total root length) in two related soils by colony enumeration and culture-independent DNA analysis. Similar to our previous findings, the numbers of copiotrophic and oligotrophic bacteria oscillated with significant harmonics along each root, independent of soil moisture or lateral roots. Shifts in amplified eubacterial 16S rDNA fragments from denaturing gradient gel electrophoresis (DGGE) analysis were detected along the roots. The most abundant and intensively amplified fragments fluctuated in phase with colony-forming unit (CFU) oscillations; fewer amplified fragments with less intensive bands fluctuated out of phase or were restricted to certain root zones. The bacterial species richness along the root was negatively correlated with the numbers of oligotrophic bacterial CFUs. Discriminant analyses on DGGE patterns distinguished between soil types, rhizosphere and bulk soil, and waxing and waning phases in the oscillations along roots. Bacterial compositions shifted within oscillations but were repeated from oscillation to oscillation, supporting the idea that the most abundant bacterial taxa were growing and dying over time and consequently in space, whereas other taxa counterfluctuated or hardly responded to the substrate supplied by the passing root tip.

Modeling wave-like dynamics of oligotrophic and copiotrophic bacteria along wheat roots in response to nutrient input from a growing root tip

Dynamics of oligotrophic bacteria (OB) have not been modeled in soil nor along roots. We extended a spatial–temporal model “BACWAVE”, describing wave-like dynamics of copiotrophic bacteria (CB) isolated on C-rich media to include dynamics of OB isolated on C-poor media and broad-range bacteria (BRB) that can grow on both types of media. BACWAVE simulates wave-like distributions of bacteria along wheat roots from their temporal dynamics with growth and death rates depending on readily utilizable substrate (RUS) concentrations, consisting of a pulse of substrate from a passing root tip and constant substrate background flux (BGF) from decaying root cortex, dead bacterial cells and soil organic matter. For this paper, colony forming units (CFUs) of bacteria isolated on poor and rich media from wheat roots (24 samples along each root) in a low C soil (0.7% C) were transformed from spatial CFUs to temporal biomass, taking root growth rate, bacterial cell sizes and cultivability into account. Contrary to the relative growth rates of CB and BRB, which increase with substrate according to Monod equations, the relative growth rate of OB is related to substrate concentration according to a modified Monod equation with a quadratic inhibition term. Relative death rates differ between trophic groups in that CB and BRB death rates decrease monotonically with substrate concentration, while the OB death rate first decreases and then increases with substrate concentration. Model parameters and initial values of state variables were estimated with an iterative optimization method based on experimental data, and fell in the range of values reported in the literature. Initial microbial biomass and kinetic parameters were lower for OB than for BRB and CB. The modified model was tested with an independent data set of bacteria along wheat roots in a soil with higher C content (1% C). BGF and initial microbial populations were higher than for the calibration data set, but other model parameters were the same for both data sets. A satisfactory fit was obtained between experimental and modeled CFUs on rich and poor media.

Immobilization of Oligotrophic Bacteria by Absorption on Porous Carriers

Immobilization of Oligotrophic Bacteria by Absorption on Porous Carriers

Effects of organic versus conventional management on chemical and biological parameters in agricultural soils

A comparative study of organic and conventional arable farming systems was conducted in The Netherlands to determine the effect of management practices on chemical and biological soil properties and soil health. Soils from thirteen accredited organic farms and conventionally managed neighboring farms were analyzed using a polyphasic approach combining traditional soil analysis, culture-dependent and independent microbiological analyses, a nematode community analysis and an enquiry about different management practices among the farmers. Organic management, known primarily for the abstinence of artificial fertilizers and pesticides, resulted in significantly lower levels of both nitrate and total soluble nitrogen in the soil, higher numbers of bacteria of different trophic groups, as well as larger species richness in both bacteria and nematode communities and more resilience to a drying–rewetting disturbance in the soil. The organic farmers plough their fields less deeply and tend to apply more organic carbon to their fields, but this did not result in a significantly higher organic carbon content in their soils. The levels of ammonium, organic nitrogen, phosphate and total phosphorus did not differ, significantly between the soils under different management. Fifty percent of the conventional Dutch farmers also used organic fertilizers and the numbers of farmers using a green crop fertilizer did not differ between the two management types. Soil type – clayey or sandy soil – in general had a much stronger effect on the soil characteristics than management type. The soil type influenced pH, nitrate, ammonium, phosphate and organic carbon levels as well as numbers of oligotrophic bacteria and of different groups of nematodes, and different diversity indices. With the collected data set certain soil characteristics could also be attributed to the use of different management practices like plow depth, crop or cover crop type or to the management history of the soil.

Bacterial communities associated with the rhizosphere of transgenic Bt 176 maize (Zea mays) and its non transgenic counterpart

The effect of transgenic Bt 176 maize on the rhizosphere bacterial community has been studied with a polyphasic approach by comparing the rhizosphere of Bt maize cultivated in greenhouse with that of its non transgenic counterpart grown in the same conditions. In the two plants the bacterial counts of the copiotrophic, oligotrophic and sporeforming bacteria, and the community level catabolic profiling, showed no significant differences; differences between the rhizosphere and bulk soil bacterial communities were evidenced. Automated ribosomal intergenic spacer analysis (ARISA) showed differences also in the rhizosphere communities at different plant ages, as well as between the two plant types. ARISA fingerprinting patterns of soil bacterial communities exposed to root growth solutions, collected from transgenic and non transgenic plants grown in hydroponic conditions, were grouped separately by principal component analysis suggesting that root exudates could determine the selection of different bacterial communities.

Bacterial role in the decomposition of marine-derived material (penguin guano) in the terrestrial maritime Antarctic

Bacterial decomposition of Adélie Penguin ( Pygoscelis adeliae) guano was followed during 42 days exposure in a rookery in Admiralty Bay, King George Island, South Shetland Islands, Antarctica. Bacterial abundance, both total counts (TC) determined by epifluorescence microscopy, and colony forming units (CFU) determined on nutrient media, was enhanced by an air temperature of between 7 and 11 °C, while temperatures above and below this negatively affected abundance. Optimal temperatures for guano decomposition ranged from 3 to 11 °C. Increasing wind velocity positively influenced photoautotrophic bacteria (TAC: total autotrophic bacteria count); photoautotrophs were enumerated during epifluorescence microscopy by their autofluorescence. Guano dry weight attained the lowest value of 74% of initial dry weight after 20 days in situ exposure. Changes in guano resulted from decomposition of the component fats, proteins, chitin, nitrogen and carbon, as well as of mineral recycling (Ca, P, Mg, and others). All transformations accompanied bacterial growth, with TC and CFU both attaining 10 11 cells g −1 d wt of guano. Total bacterial biomass (TBB) increased from 594 μg C g −1 dry weight in fresh guano, to 9101 μg C g −1 dry weight after 42 days exposure in situ. Mean cell volume (MCV) also increased from 0.236 to 0.343 μm 3. Photoautotrophic bacteria were numerically the smallest TC fraction throughout the incubation, with TAC to TC ratio ranging from 0.01 to 0.22%. Culturable bacteria abundance in guano increased dramatically from 0.28% of TC (in fresh guano) to 26% (3-h day), and 90% (42nd day) of TC. Within the total CFU population, copiotrophic bacteria were ca. two orders of magnitude more abundant than oligotrophic bacteria. Chitinolytic bacteria in guano were detected only late in the incubation; by 42 days, >40% of the initial chitin content remained. This material may comprise a significant fraction of the soil in the penguin rookery. Bacteria cultivated from the penguin guano displayed high morphophysiological diversity.

Influence of the incubation temperature on the reaction of oligotrophic bacteria to stress

Representatives of five genera of psychroactive oligotrophic bacteria, Arcocella, Renobacter, Spirosoma, Caulobacter, and Methylobacterium, were for the first time shown to be capable of growing at a negative temperature (-2 degrees C). Long-term cultivation (for 116 days) at a low temperature under limitation by the carbon source is stressful for oligotrophic bacteria and leads to the death of a part of the cell population. The number of viable cells of Caulobacter crescentus decreased by two-three orders of magnitude. Over the studied period of time, Renobacter vacuolatum cells retained viability at a low temperature, whereas at the room temperature, the titer of colony-forming cells decreased by two orders of magnitude under starvation stress.

Glaciecola polaris sp. nov., a novel budding and prosthecate bacterium from the Arctic Ocean, and emended description of the genus Glaciecola.

Four strains of cold-adapted, strictly aerobic and facultative oligotrophic bacteria were isolated from polar seas and investigated using a polyphasic taxonomic approach. Two strains (LMG 21857T and LMG 21854) derive from Arctic sea water whereas the other two strains (LMG 21855 and LMG 21858) were isolated from Antarctic sea water. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these strains belong to the gamma-subclass of the Proteobacteria and are related to the genus Glaciecola, with 98.0-99.7 % sequence similarity to Glaciecola mesophila and 94.2-95.3 % sequence similarity to Glaciecola punicea, their nearest phylogenetic neighbours. Two strains (LMG 21855 and LMG 21858) were identified as G. mesophila, whereas DNA-DNA hybridization results and differences in phenotypic characteristics showed that the other two strains (LMG 21857T and LMG 21854) constitute a novel species within the genus Glaciecola, with a DNA G + C content of 44.0 mol%. The isolates are Gram-negative, chemoheterotrophic, motile, rod-shaped cells that are psychrotolerant and moderately halophilic. Buds can be produced on mother cells and on prosthecae. Branch formation of prosthecae occurs. Whole-cell fatty acid profiles of the isolates are very similar and include C(16 : 0) and C(16 : 1)omega7c as the major fatty acid components. On the basis of genotypic and phenotypic properties, a novel species of the genus Glaciecola is described, for which the name Glaciecola polaris sp. nov. is proposed, with isolate LMG 21857T (= CIP 108324T = ARK 150T) as the type strain. An emended description of the genus Glaciecola is presented.

Email consultations in health care: 1—scope and effectiveness

<h3>Abstract</h3> Bacterial decomposition of organic matter in soils is generally believed to be mainly controlled by the accessibility of bacteria to their substrate. The influence of bacterial metabolic traits on...

The effect of cleaning and disinfecting the sampling well on the microbial communities of deep subsurface water samples

Our knowledge of the microbial characteristics of deep subsurface waters is currently very limited, mainly because of the methods used to collect representative microbial samples from such environments. In order to improve this procedure, a protocol designed to remove the unspecific, contaminant biofilm present on the walls of an approximately 800 m deep well is proposed. This procedure included extensive purges of the well, a mechanical cleaning of its wall, and three successive chlorine injections to disinfect the whole line before sampling. Total bacterial counts in water samples decreased from 2.5 x 10(5) to 1.0 x 10(4) per millilitre during the cleaning procedure. Culture experiments showed that the first samples were dominated by sulfate-reducers and heterotrophs, whereas the final sample was dominated by oligotrophic and hydrogenotrophic bacteria. Community structures established on the diversity of the 16S rRNA genes and data analysis revealed that the water sample collected, after a purge without removal of the biofilm, was characterized by numerous phyla which are not representative of the deep subsurface water. On the other hand, several bacterial phyla were only detected after the full cleaning of the well, and were considered as important components of the subsurface ecosystem which would have been missed in the absence of well cleaning.

Temporal Variability of Microbial Populations and Enzyme Activities of No-tillage Soils in Argentina

Work in temperate regions has shown that long-term no-tillage (NT) affects microbiological and biochemical properties of soils. However, relatively little research has been done on this in South America or on early microbial responses after converting to NT. Enzyme activities respond to NT but information is needed on how these assays are related to the microbial populations. The goal of this research was to study temporal dynamics of microbiological and enzyme properties of soils (0–10 cm depth) under NT systems at three on-farm sites located in the primary agricultural region of Argentina. The study had a split plot design with two main plot (medium-term) treatments of years under NT (1–3 or 4–7 years) and a subplot (season) treatment of eight seasonal samplings (repeated measures) over a two-year period. Oligotrophic bacteria counts and dehydrogenase, catalase, phosphotriesterase and urease activities often showed seasonal affect with an increase over the two-year period within each range of NT years. However, seasonal variability was not closely related to seasonal climatic patterns. Urease activity had the highest variation within seasons. Soils after 4–7 years NT had 14% greater heterotrophic bacteria counts (P < 0.05) than soils after 1–3 years of NT. Ureolytic bacteria and filamentous fungi populations, and microbial biomass C were relatively stable in both the seasonal and medium-term NT periods. Of the physical and chemical properties, only soil water content had significant correlations with the microbiological properties (r = 0.52 to 0.77, P < 0.001). The results suggest that NT was improving soil biological as most properties were increasing over the years (P > 0.05) and that these changes were maintained over short-term seasonal sampling periods.

Inter-relationship between number of microorganisms and spring barley yield and degree of soil contamination with copper

The purpose of the study has been to determine the effect of soil contamination with copper on the modification of microbial number and spring barley yield and to assess whether spores of actinomycete Streptomyces odorifer and Streptomyces viridis were used for detoxification of copper polluted soils. The tests were performed in a pot experiment, which was conducted on two types of soil: Eutric Cambisol soil derived from light loamy sand and Eutric Cambisol soil derived from light loam. The results showed that number of all analysed microorganisms was significantly negatively correlated with a degree of soil contamination by copper, but positively correlated with the yield of spring barley. In general, the adverse impact of copper on the development of oligotrophic bacteria and their spores, eutrophic bacteria and their spores as well as actinomycetes and fungi was much weaker in more compact (light loam) than lighter (light loamy sand) soil. Copper had a strong toxic effect on spring barley and significantly inhibits the growth and development of the plants. An inoculum containing spores of Streptomyces viridis and Streptomyces odorifer did not alleviate the negative response of spring barley to copper contamination of soil, although it had positive influence on the growth of some microorganisms.