Functional Diversity Of Microorganisms Research Articles

Seasonality and vegetation shape the taxonomic and functional diversity of microorganisms in islands of fertility of a semi-arid region in the Colombian tropics

The islands of fertility or resource islands play a crucial role in combating desertification, as they harbor diverse microbial communities essential for their establishment. The objective of this study was to determine the taxonomic and functional diversity of soil microorganisms in a semi-arid region of the Colombian tropics using a metagenomic approach. To achieve this, we sampled three species of nurse trees as well as bare soil during both the dry and wet seasons. Total DNA was extracted and sequenced extensively. Taxonomic diversity was established by comparing against the SILVA database, while functional diversity was determined using the DIAMOND program and the KEGG database. The analysis unveiled seasonal microbial dynamics influenced by vegetation cover. Islands of fertility exhibited higher diversity and nutritional value compared to bare soil. Wet season conditions boosted microbial diversity, narrowing the gap between vegetated and unvegetated soils. Under drought conditions, Proteobacteria predominated in the resource islands, while Actinobacteria prevailed in the bare soil. Both islands of fertility and the rainy season are significant drivers of microbial communities in these semi-arid environments. The presence of unique genera indicated specialized adaptations, revealing an under-explored microbial diversity. Although complete methanogenesis was absent, methane oxidation pathways were detected. Bacteria demonstrated notable adaptations for nitrate reduction, even under organic substrate limitation. Organic matter and anaerobic microenvironments could play a crucial role in nitrate reduction and denitrification. Sulfate reduction prevailed during the dry season, whereas thiosulfate oxidation was more prominent during the wet season. These findings underscore the remarkable adaptability of microbial communities in challenging environments and provide key insights for addressing desertification in semi-arid zones.

The application of the photo-electro-Fenton process in the treatment of wastewater reduces the abundance of genes associated with pathogenicity factors, antibiotic resistance, and metabolism: A metagenomic analysis.

The objective of this work was to determine the effect of advanced oxidation systems on the taxonomic and functional diversity of pathogenic microorganisms in the effluent of the wastewater treatment plant in Bogotá - Colombia (“El Salitre” WWTP) by metagenomics analysis. The taxonomic and functional diversity of the microorganisms, before and after oxidation treatment, was determined by Illumina mass sequencing, detecting human pathogenic genera as Pseudomonas (28.0%), Arcobacter (10.0%), Aeromonas (4.0%), Sulfurospirillum (4.0%), Salmonella (3.0%), and Clostridiales (3.0%). Likewise, pathogenicity factors such as antimicrobial resistance genes (ARGs) also were detected in high abundances (∼5% of metagenome reads). In the effluent treated with the photoelectro-Fenton system (for 5, 30, and 60 min), a significant reduction of pathogenicity factors was observed in all cases. ARGs, chemotaxis, quorum sensing, secretion systems, and toxins of pathogenic bacteria (such as Arcobacter, Pseudomonas, Serratia, and Salmonella) were reduced at near-zero log2 values, demonstrating that the photoelectro-Fenton process is a promising alternative to reduce the biological risk associated with this pathogenicity factors.

Revealing the Mechanism of Huazhi Rougan Granule in the Treatment of Nonalcoholic Fatty Liver Through Intestinal Flora Based on 16S rRNA, Metagenomic Sequencing and Network Pharmacology.

Background: The incidence of Nonalcoholic Fatty Liver (NAFL) is increasing year by year, growing evidence suggests that the intestinal flora plays a causative role in NAFL. Huazhi Rougan Granule (HRG) is commonly used in the clinical treatment of NAFL. It is reported that it can reduce lipids and protect the liver, but no research has confirmed whether the drug’s effect is related to the intestinal flora. Therefore, we investigated whether the effect of HRG is related to the regulation of intestinal flora to further explore the mechanism of HRG in the treatment of NAFL through intestinal flora. Methods: In this study, C57BL/6J mice were fed a high-fat diet for 8 weeks, and the high-fat diet plus HRG or polyene phosphatidylcholine capsules were each administered by gavage for 4 weeks. High-throughput sequencing, network pharmacology, and molecular docking were used to explore the mechanism of HRG in the treatment of NAFL through intestinal flora. Results: HRG treatment can reduce body weight gain, lipid accumulation in liver and lipogenesis and reduce serum biochemical indexes in high-fat-fed mice. Analysis of intestinal flora showed that HRG changed the composition of intestinal flora, which was characterized by a decrease in the Firmicutes/Bacteroidetes ratio. Moreover, the species distribution was significantly correlated with AKP, HDL-C, and TG. Metagenetic analysis showed that HRG altered the functional composition and functional diversity of microorganisms, which was mainly characterized by an increase in the abundance of metabolic pathways. The network pharmacology results show that the mechanism of HRG in the treatment of NAFL through intestinal flora is mainly reflected in the biological process of gene function and related to infectious diseases, immune systems, and signal transduction pathways, such as cytokine-cytokine receptor interaction, Chagas disease, IL-17 signaling pathway and other signaling pathways. Conclusion: These results strongly suggest that HRG may alleviate NAFL by preventing IFD.

How Do the Players Play? A Post-Genomic Analysis Paradigm to Understand Aquatic Ecosystem Processes.

Culture-independent and meta-omics sequencing methods have shed considerable light on the so-called “microbial dark matter” of Earth’s environmental microbiome, improving our understanding of phylogeny, the tree of life, and the vast functional diversity of microorganisms. This influx of sequence data has led to refined and reimagined hypotheses about the role and importance of microbial biomass, that paradoxically, sequencing approaches alone are unable to effectively test. Post-genomic approaches such as metabolomics are providing more sensitive and insightful data to unravel the fundamental operations and intricacies of microbial communities within aquatic systems. We assert that the implementation of integrated post-genomic approaches, specifically metabolomics and metatranscriptomics, is the new frontier of environmental microbiology and ecology, expanding conventional assessments toward a holistic systems biology understanding. Progressing beyond siloed phylogenetic assessments and cataloging of metabolites, toward integrated analysis of expression (metatranscriptomics) and activity (metabolomics) is the most effective approach to provide true insight into microbial contributions toward local and global ecosystem functions. This data in turn creates opportunity for improved regulatory guidelines, biomarker discovery and better integration of modeling frameworks. To that end, critical aquatic environmental issues related to climate change, such as ocean warming and acidification, contamination mitigation, and macro-organism health have reasonable opportunity of being addressed through such an integrative approach. Lastly, we argue that the “post-genomics” paradigm is well served to proactively address the systemic technical issues experienced throughout the genomics revolution and focus on collaborative assessment of field-wide experimental standards of sampling, bioinformatics and statistical treatments.

Metatranscriptomic characterization of the bacterial community of a contaminated mangrove from the Caribbean

Mangroves are considered biodiversity hotspots threatened by various anthropogenic tensors such as pollution, which affect the taxonomic and functional diversity of microorganisms and therefore the stability of the ecosystem. Despite metagenomic work, knowledge of gene expression in contaminated mangroves is limited. Our general objective was to characterize the metatranscriptome at the taxonomic and functional level of bacteria associated with nutrient cycling and xenobiotic degradation of a mangrove contaminated by wastewater from the Colombian Caribbean. Total RNA was extracted from three soil samples from a mangrove affected by sewage for the construction of the cDNA library, and sequencing by the Illumina HiSeq 4000 platform. We found a domain of the phylum Firmicutes and Proteobacteria, represented mainly by Bacillus and Desulfuromonas respectively. Functional annotation showed high gene expression in metabolic pathways related to carbohydrate metabolism and processing of genetic information. Regarding biogeochemical cycles, the highest transcriptional activity was found in the assimilation of formaldehyde (methane metabolism), dissimilatory nitrate reduction (nitrogen metabolism), and reduction of sulfate (sulfur metabolism), which indicates a predominance of anaerobic processes and, decomposition of organic matter. Benzoate degradation was the pathway with the highest transcriptional activity in the degradation of xenobiotics. The predominance of few taxonomics could indicate selection of taxonomic groups by wastewater, advanced ecosystem degradation and loss of ecosystem resilience future.

Microbial Community Analysis of Native Pinus sylvestris L. and Alien Pinus mugo L. on Dune Sands as determined by Ecoplates

The Curonian Spit (Lithuanian: Kursiu nerija) is a 98 km long, thin, curved sand-dune spit that separates the Curonian Lagoon from the Baltic Sea coast. The Curonian Spit is home to the highest moving (drifting) sand dunes in Europe. Coniferous woods are prevalent in the Kursiu Nerija National Park (80%). These woods consist mostly of native Scots pine (Pinus sylvestris L.) and alien mountain pine (Pinus mugo L.). With the planting of non-native species, there is a need for studies evaluating the effects of alien and native plant species on soil ecosystem properties. We measured soil microbial communities from nearby pairs of native and alien pine species. Forty-two sampling sites of close-growing P. sylvestris and P. mugo were selected. To measure the soil microbial activity in these sites, we used Biolog EcoPlates. We found that the functional diversity of microorganisms that use carbon sources was significantly greater in the mature pine stands. Microbial functional diversity was also greater in the soils of native pine stands. Differences between activity and functional diversity in newly established and old stands were also identified.

Taxonomic and Functional Diversity of Microbial Communities as an Indicator of the Effectiveness of Water Treatment in Constructed Wetlands

The article provides an overview devoted to wastewater treatment from nutrients and organic toxicants in Constructed Wetlands (CW). The analysis of the main microbiological processes of wastewater purification in these systems is made. It is shown that biological indicators and parameters of the plant, obtained by the molecular biological methods are the basis for the understanding and tracking of ongoing processes. Taxonomic and functional diversity of microorganisms in CW may be an indicator of the effectiveness of these treatment systems, including the effectiveness of xenobiotics removal.

Effect of rock dust-amended compost on the soil properties, soil microbial activity, and fruit production in an apple orchard from the Jiangsu province of China

ABSTRACT This study examined the effect of compost fortified with rock dust on the soil properties, soil microbial activity, and yield and fruit quality in a mature apple orchard from the Jiangsu province of China. The incorporation of rock dust significantly improved the microelement contents of Ca, Mg, Fe, Mn, Zn, B, and Al, but without increasing phytotoxicity of the compost. The fortified compost had higher metabolic activity and functional diversity of microorganisms as determined by the community-level physiological profiling with Biolog EcoPlates. The two-year incorporation of the rock dust compost into a poor-quality soil led to a significant increase in the yield with the increase of 120% and 187% compared to untreated control in 2013 and 2014, respectively. Application of the rock dust compost obviously promoted superoxide dismutase (SOD) activity and concentration of vitamin C in mature apple trees. The beneficial effects coincided with higher microbial activity and shifts in the composition of the soil microbiome. Our results demonstrate that the practice of combining the rock dust-fortified compost with NPK fertilizers provides a cost-effective way of supplying crops with macro-and micronutrients ensuring better vegetative growth and higher yields.

Functional diversity of soil microorganisms in the conditions of an ecological farming system

Abstract In the current study, we investigate the relationships among the soil functional diversity, physicochemical properties and heavy metals presence in an ecological farming system. The soil samples were collected from permanent research sites, from A soil horizons, at a depth from 0.05 m to 0.15 m, in June 2018. In fresh soil samples, we evaluated the metabolic profiles of their microbial communities, using Biolog® Eco Plates. The research showed that the soil physical properties got adjusted after a long-term application of an ecological farming system and that the measured values were stabilised, reaching the levels comparable with the average values for the relevant soil type. It is necessary to devote a continual attention to soil reaction, because soil is naturally acidified through acid atmospheric fallout as well as through calcium uptake-off by plants. The values of the selected heavy metals in the monitored period did not exceed the limit values specified in the Act No. 220/2004 Coll. Based on the results of Shannon’s diversity, we can conclude that the diversity in the investigated sites was low, from moderate to medium. The differences (3.26–3.36) among all 11 study localities were very small and not significant. There were determined the correlations between the soil functional diversity, soil physicochemical properties, and heavy metal contents. The average well colour development (AWCD) positively correlated with soil reaction and with Mg content and significantly negatively correlated with contents of Hg, Zn and Cu; equitability significantly positively correlated with soil reaction, Mg, AWCD and Shannon’s diversity. Spearman’s correlation coefficients confirmed the positive correlation between Shannon’s diversity and soil reaction, AWCD and Mg. In our study, no correlation was found between the functional diversity of microorganisms and the soil physical properties.

Application of hydrogeological and biological research for the lysimeter experiment performance under simulated municipal landfill condition

The size and chemical composition of leachates migrating into the aquifer are dependent on the parameters of the waste and the storage conditions. Lysimeter studies allow us to determine the size and chemical composition of leachates as well as the leachate water balance. Lysimeter studies were conducted on a 230-L municipal waste sample for 6 months. During the tests, the specific electrolyte conductivity, pH, Eh, and temperature, as well as the chemical composition, microbiological analysis, and profiling of physiological population level using EcoPlate™ microarrays were measured in collected leachate samples. During the entire experiment, the amounts of inflow and outflow from lysimeters were measured. To assess the existence of significant differences in the chemical component concentrations in leachates, use of Principal Component Analysis was taken into account. The maximum EC value from leachate from the lysimeter was 33 mS/cm. High concentrations of ammonium ion (up to approx. 1400 mg dm−3), chlorides (up to approx. 6800 mg dm−3), and iron (up to approx. 31 mg dm−3) were observed in the effluents. The number of enterococci in May reached 53,000 cells/100 ml. By contrast, the number of these microorganisms was about 15,000 and 16,000 CFU/100 ml in January and April, respectively. Community-level physiological profiling indicates that the activity and functional diversity of microorganisms were higher in the leachate samples obtained in winter compared to effluents collected from lysimeters in spring.

Straw and biochar strongly affect functional diversity of microbial metabolism in paddy soils

The application of straw and biochar is widely practiced for the improvement of soil fertility. However, its impact on microbial functional profiles, particularly with regard to paddy soils, is not well understood. The aim of this study was to investigate the diversity of microbial carbon use patterns in paddy soils amended with straw or straw-derived biochar in a 3-year field experiment in fallow soil and at various development stages of a rice crop (i.e., tillering and blooming). We applied the community level physiological profiling approach, with 15 substrates (sugars, carboxylic and amino acids, and phenolic acid). In general, straw application resulted in the greatest microbial functional diversity owing to the greater number of available C sources than in control or biochar plots. Biochar amendment promoted the use of α-ketoglutaric acid, the mineralization of which was higher than that of any other substrate. Principal component analyses indicated that microbial functional diversity in the biochar-amended soil was separated from those of the straw-amended and control soils. Redundancy analyses revealed that soil organic carbon content was the most important factor regulating the pattern of microbial carbon utilization. Rhizodeposition and nutrient uptake by rice plants modulated microbial functions in paddy soils and stimulated the microbial use of N-rich substances, such as amino acids. Thus, our results demonstrated that the functional diversity of microorganisms in organic amended paddy soils is affected by both physicochemical properties of amendment and plant growth stage.

Effects of bok choy on the dissipation of dibutyl phthalate (DBP) in mollisol and its possible mechanisms of biochemistry and microorganisms

Phytoremediation is an ecologically sustainable method for remediating contaminated soils, however, research on phytoremediation and its mechanisms are still rarely reported. The highest dibutyl phthalate (DBP) dissipation rate was 91% in 0–3mm bok choy rhizosphere via a 45-day rhizo-box experiment, and bok choy could regulate soil nutrients by increasing soil ammonia nitrogen (AN) and available phosphorus (AP). The biochemistry mechanism of interaction between dissolved organic matter (DOM) and DBP was also elucidated by various spectroscopy techniques. It was found that the alkyl ester in DBP produced the fastest response during the binding process, and the aromatic, hydroxyl and phenolic groups of the DOM humic-like substances preceded amide in DOM protein-like substance. It was found that DBP pollution reduced the Chao1 richness and Shannon index of bacteria in black soil via a pot experiment and high-throughput sequencing, which disturbed the metabolic activities and functional diversity of microorganisms in Mollisol. The microbial abundance increased in bok choy amendments, which has a specific microbial community structure and a high abundance of Actinobacteria and Acidobacteria. We concluded that some enriched genera were responsible for DBP dissipation, Alsobacter, Lacibacter, Myceligenerans, Schrenkiella parvula and Undibacterium. The findings of this study revealed that the possible biochemistry and microbial mechanisms of phytoremediation promoting the DBP dissipation in rhizosphere Mollisol and provided more useful information for phytoremediation of organic pollutants.

Molecular Biological Methods in Environmental Engineering.

Microorganisms can respond fast to the environmental changes, and well suited for environmental assessment. DNA and RNA are generally extracted by extraction kits. After extraction, molecular biological methods including genomics, transcriptomics, proteomics and metabolomics are applied to characterize the genetic and functional diversity of microorganisms. Quantitative PCR, FISH and mass sequence of amplicons are also described. This review provides environmental engineers and microbiologists an overview of important advancements in molecular techniques and highlights the application of these methods in diverse environments.

Biomass and activity soil microorganisms in grazing and secondary forests areasA

Sustainable livestock production generates benefits for the environment, such as water capture, increased biodiversity and carbon dioxide capture. To measure these factors in a tropical setting, in 2007 we took three samples of a milk production system in Turrialba, Cartago, Costa Rica, in areas with permanent African Star grass cover (under grazing) and a secondary forest with 15 years of regeneration. We estimated carbon content in the microbial biomass, microbial activity (breathing technique), carbon usage profile (BIOLOG ECOPLATES®) and functional diversity of microorganisms (Shannon index). Biomass carbon in the pasture was 3,3 times higher than in the forest, but microbial activity was similar. Carbon use rate ranged from 22,22 to 85,19% in the pasture (higher in the forest: 29,63 to 92,59%). In both areas growth correlated with incubation time, but the forest had more biodiversity. Pasture areas are favored by carbon deposition to the rhizosphere, while the variety of vegetation in the forest allows greater functional diversity in the use of carbon substrates.

Similar Microbial Communities Found on Two Distant Seafloor Basalts.

The oceanic crust forms two thirds of the Earth’s surface and hosts a large phylogenetic and functional diversity of microorganisms. While advances have been made in the sedimentary realm, our understanding of the igneous rock portion as a microbial habitat has remained limited. We present the first comparative metagenomic microbial community analysis from ocean floor basalt environments at the Lō’ihi Seamount, Hawai’i, and the East Pacific Rise (EPR; 9°N). Phylogenetic analysis indicates the presence of a total of 43 bacterial and archaeal mono-phyletic groups, dominated by Alpha- and Gammaproteobacteria, as well as Thaumarchaeota. Functional gene analysis suggests that these Thaumarchaeota play an important role in ammonium oxidation on seafloor basalts. In addition to ammonium oxidation, the seafloor basalt habitat reveals a wide spectrum of other metabolic potentials, including CO2 fixation, denitrification, dissimilatory sulfate reduction, and sulfur oxidation. Basalt communities from Lō’ihi and the EPR show considerable metabolic and phylogenetic overlap down to the genus level despite geographic distance and slightly different seafloor basalt mineralogy.

Identification of cadmium-resistant fungi related to Cd transportation in bermudagrass [Cynodon dactylon (L.) Pers.

Phytoremediation utilizing plants and microbes has been increasingly adopted as a green technology for cleaning up heavy metal polluted soils. Cd polluted soil and native bermudagrass from Liuyang and Zhuzhou in Hunan province of China were collected to investigate microbial diversity and isolate Cd resistant fungi, and then to determine the effect of Cd resistant fungi on Cd tolerance and transportation of bermudagrass. The functional diversity of microorganisms was evaluated using the BIOLOG Eco method. Cd-resistant fungi strain was isolated and identified as Aspergillus aculeatus based on the ribosomal internal transcribed spacer region sequence analysis. Bermudagrass was exposed to control, Cd only, and Cd plus A. aculeatus (Cd+A. aculeatus) with growth matrix (sawdust/sand=3/1 in volume). Results indicated that Cd+A. aculeatus treated bermudagrass exhibited a higher photosynthetic activity compared to Cd only treated plants. Inoculation of A. aculeatus resulted in a decrease in stem and leaf Cd concentrations, to a greater extent for Cd-sensitive than for Cd-tolerant genotype. However, inoculation of A. aculeatus increased root Cd concentration under Cd stress conditions, significantly elevated soil pH, and decreased soil water-soluble Cd concentration. These results suggested that A. aculeatus might be potentially applied to improve Cd tolerance and to reduce Cd transportation to shoot of bermudagrass.

Microbial redox processes in deep subsurface environments and the potential application of (per)chlorate in oil reservoirs.

The ability of microorganisms to thrive under oxygen-free conditions in subsurface environments relies on the enzymatic reduction of oxidized elements, such as sulfate, ferric iron, or CO2, coupled to the oxidation of inorganic or organic compounds. A broad phylogenetic and functional diversity of microorganisms from subsurface environments has been described using isolation-based and advanced molecular ecological techniques. The physiological groups reviewed here comprise iron-, manganese-, and nitrate-reducing microorganisms. In the context of recent findings also the potential of chlorate and perchlorate [jointly termed (per)chlorate] reduction in oil reservoirs will be discussed. Special attention is given to elevated temperatures that are predominant in the deep subsurface. Microbial reduction of (per)chlorate is a thermodynamically favorable redox process, also at high temperature. However, knowledge about (per)chlorate reduction at elevated temperatures is still scarce and restricted to members of the Firmicutes and the archaeon Archaeoglobus fulgidus. By analyzing the diversity and phylogenetic distribution of functional genes in (meta)genome databases and combining this knowledge with extrapolations to earlier-made physiological observations we speculate on the potential of (per)chlorate reduction in the subsurface and more precisely oil fields. In addition, the application of (per)chlorate for bioremediation, souring control, and microbial enhanced oil recovery are addressed.

The influence of winter wheat continuous cropping and fertilization on the crop yields and microbial soil diversity

The possibilities of the elimination of continuous cropping negative implications on the grain yield and microbial soil diversity were investigated. A stationary field experiment was established on Luvi-Haplic Chernozem. Statistically higher grain yield was found in the variant with mineral fertilization and straw and organic fertiliser Veget® incorporation (5.58 t.ha−1) compared with the variant with mineral fertilization only (4.87 t.ha−1) and with the variant with mineral fertilization and straw incorporation (4.90 t.ha−1). Statistically higher straw yield was found in the variant with mineral fertilization and straw and organic fertiliser Veget® incorporation (6.21 t.ha−1) compared with the variant with mineral fertilization only (4.41 t.ha−1). By cultivar Ebi, the grain yield was significantly higher in comparison to the cultivar Petrana. The lowest metabolic diversity of microbial communities and their respiration activity was found out in the variant with mineral fertilizer. On the other hand, the increase of functional diversity of microorganisms, their respiration activity and the number of cultivable bacteria was found in the variant with mineral fertilization and straw incorporation as well as in the variant with mineral fertilization and straw and organic fertiliser Veget® incorporation.

Soil microbial community changes as a result of long-term exposure to a natural CO 2 vent

The capture and geological storage of CO 2 can be used to reduce anthropogenic greenhouse gas emissions. To assess the environmental impact of potential CO 2 leakage from deep storage reservoirs on the abundance and functional diversity of microorganisms in near-surface terrestrial environments, a natural CO 2 vent (>90% CO 2 in the soil gas) was studied as an analogue. The microbial communities were investigated using lipid biomarkers combined with compound-specific stable carbon isotope analyses, the determination of microbial activities, and the use of quantitative polymerase chain reactions (Q-PCR). With this complementary set of methods, significant differences between the CO 2-rich vent and a reference site with a normal CO 2 concentration were detected. The δ 13C values of the plant and microbial lipids within the CO 2 vent demonstrate that substantial amounts of geothermal CO 2 were incorporated into the microbial, plant, and soil carbon pools. Moreover, the numbers of Archaea and Bacteria were highest at the reference site and substantially lower at the CO 2 vent. Lipid biomarker analyses, Q-PCR, and the determination of microbial activities showed the presence of CO 2-utilising methanogenic Archaea, Geobacteraceae, and sulphate-reducing Bacteria (SRB) mainly at the CO 2 vent, only minor quantities were found at the reference site. Stable carbon isotopic analyses revealed that the methanogenic Archaea and SRB utilised the vent-derived CO 2 for assimilatory biosynthesis. Our results show a shift in the microbial community towards anaerobic and acidophilic microorganisms as a consequence of the long-term exposure of the soil environment to high CO 2 concentrations.

Structural and functional diversity of soil microbial communities as a result of combined applications of copper and mefenoxam

The effects of combined application of mefenoxam and copper on soil microbial community structure and function were investigated in laboratory microcosms over 60 days. Mineralisation of 14C-mefenoxam was followed by trapping the evolved 14CO 2. The structural diversity of bacterial and fungal communities was assessed by analysing fingerprints of 16S and 18S rRNA genes and transcripts, resolved by denaturing gradient gel electrophoresis (DGGE). The functional status of the microbial community was investigated by measuring the activities of cellobiohydrolase, hemicellulase, β-glucosidase, phosphatase, aminopeptidase, chitinase and laccase. Results showed that copper application had no significant effect on the mineralisation rate of mefenoxam, although only 5.4% of the applied radioactivity was converted to 14CO 2. Both copper and mefenoxam exerted selective detrimental effects on sensitive populations of fungi. In contrast, active bacterial populations were not adversely affected; instead new population structure could be observed during the exposure time. Only a few enzymes exhibited noticeable changes as a result of copper and mefenoxam treatments. Of the seven enzymes under investigation, laccase and chitinase showed an increase in their activity, which lasted till the end of the study. Thus, the study revealed a distinct effect of combined application of mefenoxam and copper both on the structural and functional diversity of microorganisms.