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PubMed2002

Contribution of microbial activity to virus reduction in saturated soil.

Application of wastewater to soil may result in the contamination of groundwater and soil with pathogenic microorganisms and other biological and chemical agents. This study was performed to determine the antiviral microbial activity of soil saturated with secondary effluent. Low concentrations (0.05mg/ml) of protease pronase resulted in the inactivation of more than 90% of seeded Cox-A9 virus, whereas Poliovirus type 1, Hepatitis A virus (HAV) and MS2 bacteriophages were found to be insensitive to the enzyme activity. Exposure of Cox A9 virus to P. aeruginosa extracellular enzymes resulted in 99% inactivation of the seeded virus. Hepatitis A virus was found to be as sensitive as the Cox A9 virus, whereas Poliovirus 1 and MS2 were found to be insensitive to P. aeruginosa extracellular enzymatic activity. Furthermore, the time required for 99% reduction (T99) of Cox A9 and MS-2 Bacteriophage, at 15 degrees C, in soil saturated with secondary effluent was found to be 7 and 21 days, respectively. Faster inactivation was observed for MS2 and Cox A9 in soil saturated with secondary effluent incubated at 30 degrees C, T99 of 2 and 0.3 days, respectively. Although the concentration of the total bacterial count in the soil samples increased from 10(3) cfu/g to 10(5) cfu/g after 20 days of incubation at 30 degrees C, the proteolytic activity was below the detection level. The results of this study indicate that the virucidal effect of microbial activity is virus type dependent. Furthermore microbial activity in the soil material can be enhanced by the application of secondary effluent at higher temperature. The results also showed that MS2 bacteriophage can be used to predict viral contamination of soil and groundwater.

Conservation of Natural Resources↗
PubMed1999

Elafin (elastase-specific inhibitor) has anti-microbial activity against gram-positive and gram-negative respiratory pathogens.

Elafin (elastase-specific inhibitor) is a low molecular weight inhibitor of neutrophil elastase which is secreted in the lung. Using synthetic peptides corresponding to full-length elafin (H2N-1AVT.....95Q-OH), the NH2-terminal domain (H2N-1AVT.....50K-OH) and the COOH-terminal domain (H2N-51PGS.....95Q-OH), we demonstrate that elafin's anti-elastase activity resides exclusively in the COOH-terminus. Several characteristics of elafin suggest potential anti-microbial activity. The anti-microbial activity of elafin, and of its two structural domains, was tested against the respiratory pathogens Pseudomonas aeruginosa and Staphylococcus aureus. Elafin killed both bacteria efficiently, with 93% killing of P. aeruginosa by 2.5 microM elafin and 48% killing of S. aureus by 25 microM elafin. For both organisms, full-length elafin was required to optimise bacterial killing. These findings represent the first demonstration of co-existent anti-proteolytic and anti-microbial functions for elafin.

Antifungal Agents↗
PubMed2006

Soil microbial activity is affected by Roundup WeatherMax and pesticides applied to cotton (Gossypium hirsutum).

Adoption of glyphosate-based weed control systems has led to increased use of the herbicide with continued use of additional pesticides. Combinations of pesticides may affect soil microbial activity differently than pesticides applied alone. Research was conducted to evaluate the influence of glyphosate-based cotton pest management systems on soil microbial activity. Soil was treated with commercial formulations of trifluralin, aldicarb, and mefenoxam + pentachloronitrobenzene (PCNB) with or without glyphosate (applied as Roundup WeatherMax). The soil microbial activity was measured by quantifying C and N mineralization. Soil microbial biomass was determined using the chloroform fumigation-incubation method. Soils treated with glyphosate alone exhibited greater cumulative C mineralization 30 days after treatment than all other treatments, which were similar to the untreated control. The addition of Roundup WeatherMax reduced C mineralization in soils treated with fluometuron, aldicarb, or mefenoxam + PCNB formulations. These results indicate that glyphosate-based herbicides alter the soil microbial response to other pesticides.

Biomass↗
PubMed2003

Effect of glyphosate on the microbial activity of two Brazilian soils.

Glyphosate [N-(phosphonomethyl)-glycine] is a broad-spectrum, non-selective, post-emergence herbicide that is widely used in agricultural. We studied, in vitro, changes in the microbial activity of typical Hapludult and Hapludox Brazilian soils, with and without applied glyphosate. Glyphosate was applied at a rate of 2.16 mg glyphosate kg(-1) of soil and microbial activity was measured by soil respiration (evolution of CO(2)) and fluorescein diacetate (FDA) hydrolysis over a period of 32 days. We found an increase of 10-15% in the CO(2) evolved and a 9-19% increase in FDA hydrolyses in the presence of glyphosate compared with the same type of soil which had never received glyphosate. Soil which had been exposed to glyphosate for several years had the strongest response in microbial activity. Most probable number (MPN) counts showed that after 32 days incubation the number of actinomycetes and fungi had increased while the number of bacteria showed a slight reduction. After the incubation period, high pressure liquid chromatography (HPLC) detected the glyphosate metabolite aminomethyl phosphonic acid (AMPA), indicating glyphosate degradation by soil microorganisms.

Bacteria↗
PubMed2001

Anti microbial activity of dimercaptosuccinic acid (DMSA): a new chelating agent.

Successful outcome of endodontic treatment depends on elimination of bacteria and their products present in the root canal. It has been reported that after careful chemicomechanical preparation, smear layer is formed on the walls of canal, which contains bacteria and their products. Chelating agents, when used during chemicomechanical preparation, remove the smear layer. DMSA--a new chelating agent, when used in root canals, removes the smear layer more than EDTA when used as irrigant in root canals. This study was conducted to determine whether DMSA has anti microbial activity and compare it with EDTA. The results show that EDTA (10% & 15%) had marked anti microbial activity, both on culture plates and in broth. DMSA (10% & 15%) did not show anti microbial activity on culture plates while in broth it had marked activity.

Anti-Infective Agents, Local↗
PubMed2001

Development of respirometry methods to assess the microbial activity of thermophilic bioleaching archaea.

Respirometry methods have been used for many years to assess the microbial activity of mainly heterotrophic bacteria. Using this technique, the consumption of oxygen and evolution of carbon dioxide for heterotrophic carbon catabolism can be used to assess microbial activity. In the case of autotrophic bioleaching bacteria, carbon dioxide is used as a carbon source resulting in the consumption of both oxygen and carbon dioxide. The use of such respirometry techniques at high temperatures (up to 80 degrees C) for the investigation of bioleaching Archaea, however, poses particular difficulties. At these elevated temperatures, the solubility of oxygen into the liquid phase is particularly poor. This work details specific methods by which high temperature constraints are overcome while monitoring the activity of thermophilic Archaea using a Micro-Oxymax respirometer (Columbus Instruments). The use of elevated headspace oxygen concentrations, in order to overcome low oxygen solubility, is demonstrated as well as the effect of such elevated oxygen concentrations on microbial oxygen consumption rates. The relative rates of oxygen and carbon dioxide consumption are also illustrated during the oxidation of a chalcopyrite concentrate. In addition, this paper details generic methods by which respirometry data can be used to quantify inhibitory effects of a compound such as Na(2)SO(4). The further use of such data in predicting minimum hydraulic reactor retention times for continuous culture bioleaching reactors, as a function of concentration of potentially inhibitory compounds, is also demonstrated.

Archaea↗
PubMedDate not supplied

Spatial variability of in situ microbial activity: biotracer tests.

Biotracer tests have been proposed as a means by which to characterize the in situ biodegradation potential for field-scale systems. In this study, field experiments were conducted at two sites to evaluate the utility of the biotracer method for characterizing the spatial variability of microbial activity. The first site is a mixed waste-contaminated surficial aquifer in Utah, and the second site is a chlorinated solvent-contaminated regional aquifer in Tucson, Arizona. Mass recovery of the biotracer decreased approximately linearly with increasing residence time for the Tucson site. Similar behavior was observed at the Utah site, except in the region adjacent to the injection zone, where percent recoveries were much lower than those predicted using a correlation determined using data collected downgradient of the injection zone. First-order biodegradation rate coefficients obtained from model calibration of the tracer data varied between 0.2 and 0.5/day for the Tucson site. For the Utah site, the values varied between 0.1 and 0.6/day downgradient of the injection wells, and between 0.7 and 2.6/day near the injection wells. Considering the large range over which biodegradation rate coefficients can vary, the rate coefficient exhibited relatively minimal spatial variability (factor of 2.5) for the Tucson site. Conversely, the spatial variability of the rate coefficient was an order of magnitude greater for the Utah site. These differences in variability are consistent with conditions associated with the respective sites. For example, the greater microbial activity observed in the vicinity of the injection wells for the Utah site is consistent with the biomass distribution determined from analysis of core samples, which shows larger bacterial cell densities for the region near the injection wells. These results illustrate the utility of biotracer tests for in situ characterization of microbial activity (e.g., biodegradation potential), including evaluation of potential spatial variability.

Biodegradation, Environmental↗
PubMedDate not supplied

Distribution of chromium contamination and microbial activity in soil aggregates.

Biogeochemical transformations of redox-sensitive chemicals in soils can be strongly transport-controlled and localized. This was tested through experiments on chromium diffusion and reduction in soil aggregates that were exposed to chromate solutions. Reduction of soluble Cr(VI) to insoluble Cr(II) occurred only within the surface layer of aggregates with higher available organic carbon and higher microbial respiration. Sharply terminated Cr diffusion fronts develop when the reduction rate increases rapidly with depth. The final state of such aggregates consists of a Cr-contaminated exterior, and an uncontaminated core, each having different microbial community compositions and activity. Microbial activity was significantly higher in the more reducing soils, while total microbial biomass was similar in all of the soils. The small fraction of Cr(VI) remaining unreduced resides along external surfaces of aggregates, leaving it potentially available to future transport down the soil profile. Using the Thiele modulus, Cr(VI) reduction in soil aggregates is shown to be diffusion rate- and reaction rate-limited in anaerobic and aerobic aggregates, respectively. Thus, spatially resolved chemical and microbiological measurements are necessary within anaerobic soil aggregates to characterize and predict the fate of Cr contamination. Typical methods of soil sampling and analyses that average over redox gradients within aggregates can erase important biogeochemical spatial relations necessary for understanding these environments.

Bacteria, Aerobic↗
PubMedDate not supplied

Soil microbial activities and carbon and nitrogen fixation.

Soil microbial activity that reflects microbiological processes of soil microorganisms is the potential indicator of soil quality, as plants rely on soil microorganisms to mineralize organic nutrients for growth and development. Soil microorganisms also process plant litter and residues into soil organic matter, a direct and stable reservoir of carbon and nitrogen that consists of living and dead organic materials subject to rapid biological decomposition. In natural systems, the action of soil microorganisms is a major determinant of efficient nutrient cycling. This paper reviews the current state of knowledge on the fate of soil microorganisms in terms of carbon and nitrogen fixation.

Bacteria↗
PubMed2005

Total RNA concentration as an index of microbial activity and oxygen supply in an oxidation ditch.

Total RNA and chromosomal DNA concentrations at a municipal wastewater treatment plant with an oxidation ditch (OD) were monitored for 1.5 years using commercial extraction kits for DNA and RNA. No parameters correlated with the chromosomal DNA concentration. The total RNA concentration exhibited better correlation than the solids retention time and the mixed liquor suspended solids with the removal rate of total organic carbon, and can be regarded as an index of microbial activity. The total RNA concentration varied with a cycle of one year and increased at lower water temperatures in this OD. When diffusion theory was taken into account, it was found that the oxygen dissolution rate increased at lower temperature, and a small change in the oxygen dissolution rate caused a large variation in microbial activity and also affected nitrification and denitrification. The information was insufficient to clarify the various reaction relationships, but total RNA concentration will likely be useful as an index of microbial activity in actual wastewater treatment reactors.

Bacteria, Aerobic↗
PubMed2005

Effect of freezing and thawing on microbial activity and glyphosate degradation in two Norwegian soils.

Little research has been done on pesticide dissipation in cold climates and there is a need to focus on the influence of climate on pesticide degradation in soil. Glyphosate, N-(phosphonomethyl)glycine, is a herbicide frequently used for controlling perennial weeds through application after harvest and was used as a model compound for this study. The effect of freeze-thaw activity on the availability of glyphosate in soil, and consequently its mineralization by soil microorganisms, was studied through laboratory incubations of repacked soil cores treated with 14C-labelled glyphosate and subjected to different freeze-thaw treatments. Winter simulation regimes applied were constant thaw (+5 degrees C), constant freezing (-5 degrees C), unstable conditions with short fluctuations (24 h of -5 degrees C followed by 24 h of +5 degrees C), and long duration fluctuations (3 weeks of -5 degrees C followed by 3 weeks of +5 degrees C). Distribution of 14C-glyphosate was followed during the incubation through measurements of the mineralized fraction (14CO2), soil water fraction, KOH extractable fraction, and non-extractable fraction. Microbial parameters used to characterize the soils were estimates of size of microbial biomass, overall microbial activity and microbial diversity. The constant freezing treatment exhibited the lowest amount of glyphosate mineralization. The constant thawed treatment and the treatments with fluctuating temperature exhibited significantly increased mineralization. These results were in accordance with the observed concentration of glyphosate in soil water; the higher the activity, the lower the concentration. The amount of glyphosate extractable with KOH and the resulting non-extractable fraction, however, were not significantly affected by soil type or temperature regime. The glyphosate mineralization pattern was comparable with the overall microbial activity in the soils. Observed different levels of diversity might explain some of the difference in total glyphosate mineralization between soils.

Biodegradation, Environmental↗
PubMed1984

Impact of an oil field effluent on microbial activities in a Wyoming river.

The survival, functions, and physiological diversity of autochthonous sediment microbiota were examined in situ at five stations along the Little Popo Agie River, WY; one station above, one at, and three below a discharge point for oil wastewater from Union Oil Company's Dallas Field. Below the oil wastewater discharge point there were increases in electron-transport activity, carbon dioxide production, and microbial populations of heterotrophs, ammonifiers, hexadecane degraders, starch hydrolyzers, protein hydrolyzers, and sulfate reducers. At a station 1420 m below the discharge point, however, overall sediment microbial activities and all of the physiological groups of bacteria, except hexadecane-degrading microbiota, were at levels comparable with those at the control station above the discharge point. Similarly, mineralization of glucose, amino acids, hexanoic acid, and hexadecane was elevated at stations directly below the discharge point, but appeared to subside rapidly. Xenobiotic biodegradation potential of the sediments varied with the chemical and the sample location and was not directly related to oil residue levels in the sediment. Microorganisms thus appeared to maintain physiological diversity and increased in numbers and activity in a riverine environment that contained petroleum hydrocarbon concentrations known to be deleterious to freshwater fish and macrobenthic communities.

Alkanes↗
PubMed2005

New field method: gas push-pull test for the in-situ quantification of microbial activities in the vadose zone.

Quantitative information on microbial processes in the field is important. Here we propose a new field method, the "gas push-pull test" (GPPT) for the in-situ quantification of microbial activities in the vadose zone. To evaluate the new method, we studied microbial methane oxidation above an anaerobic, petroleum-contaminated aquifer. A GPPT consists of the injection of a gas mixture of reactants (e.g., methane, oxygen) and nonreactive tracer gases (e.g., neon, argon) into the vadose zone and the subsequent extraction of the injection gas mixture together with soil air from the same location. Rate constants of gas conversion are calculated from breakthrough curves of extracted reactants and tracers. In agreement with expectations from previously measured gas profiles, we determined first-order rate constants of 0.68 h(-1) at 1.1 m below soil surface and 2.19 h(-1) at 2.7 m, close to the groundwater table. Co-injection of a specific inhibitor (acetylene) for methanotrophs showed that the observed methane consumption was microbially mediated. This was confirmed by increases of stable carbon isotope ratios in methane by up to 42.6 %. In the future, GPPTs should provide useful quantitative information on a range of microbial processes in the vadose zone.

Air Movements↗
PubMed2003

Release of Ni and Co by microbial activity in New Caledonian ultramafic soils.

A high positive correlation was found between extractable Ni and Co contents and microbial activity of 40 ultramafic soil samples from New Caledonia, suggesting a possible role of microorganisms in the release of these two metals. A saprolite (ultramafic subsoil) and a hypermagnesian brown soil were incubated 9 months in different conditions. Ni and Co release, measured by their extractability, occurred without reduction of soil pH but did not occur when the native microflora was eliminated by heat treatment. However, when autoclaved soil was re-inoculated with a pinch of the same nonheated soil, the release of metals was recorded. The concentrations of extractable Ni and Co were much higher in soils amended with organic compounds in which microbial activity was enhanced, but only if the soil was not heat treated. The presence of Grevillea exul, a metal-tolerant plant, stimulated the metal release process, but the stimulation was less effective than it was in the compost-amended soil without plant. The influence of the plant in extractable Ni and Co contents in this amended soil was not significant. The release of the two metals therefore seemed to be induced by the activity of specialized organotrophic microorganisms.

Bacterial Physiological Phenomena↗
PubMed1995

Anti-microbial activity of human CAP18 peptides.

BACKGROUND: CAP18 derived from rabbit leukocytes is a 142-amino acid protein recently demonstrated to have Lipopolysaccharide (LPS) binding and anti-microbial activity. The C-terminal 37 amino acids of rabbit CAP18 (CAP18(106-142) comprise the LPS-binding and anti-microbial domain. The homologous domain of human CAP18 (huCAP18(104-140) was identified from the recently cloned human CAP18 cDNA. OBJECTIVES: To evaluate the antimicrobial activity of C-terminal peptides derived from human CAP18. STUDY DESIGN: Prepare synthetic human CAP18(104-140) and study anti-microbial activity versus various gram-negative and gram-positive bacteria. RESULTS: Synthetic human CAP18(104-140) has broad anti-microbial activity versus both gram-positive (IC50 = 2.5 micrograms/ml) and gram-negative bacteria (IC50 = 0.5-5 micrograms/ml). Susceptible strains include Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhimurium. A 32-amino acid peptide lacking five amino acids from the C-terminus of CAP18(104-140) has higher activity. Unlike previously characterized anti-microbial peptides derived from granulocyte proteins, CAP18(104-140) is active in serum. CONCLUSIONS: Human CAP18(104-140) or a derivative peptide may have therapeutic potential for bacterial sepsis.

Amino Acid Sequence↗
PubMed2003

Simplified method for estimation of microbial activity in compost by ATP analysis.

A simplified method using ATP analysis was proposed to estimate the time course of microbial activity during composting. A compost sample was suspended in distilled water and its filtrate was used to estimate the ATP content in the compost by the luciferine-luciferase fluorescence reaction. The method permitted the rapid and simple determination of ATP in the compost and was successfully applied to monitor the time course of the microbial activity in the laboratory-scale composting process. The analytical simplicity in this method greatly improved the field-applicability of the ATP analysis for the composting process monitoring.

Adenosine Triphosphate↗
PubMedDate not supplied

Synthesis and anti-microbial activities of choline-like quaternary ammonium chlorides.

New choline-like quaternary ammonium chlorides were obtained. The work-up procedure of synthesis was quick and efficient. The obtained chlorides showed anti-microbial activities. Quaternary ammonium chlorides derivatives of deanol esters exhibited strong activity and wide anti-bacterial spectra, similar to the activity of benzalkonium chloride. The relationship between chemical structure and anti-microbial activity was analyzed by the QSAR method.

Ammonium Chloride↗
PubMed2006

Microbial activity in an acid resin deposit: biodegradation potential and ecotoxicology in an extremely acidic hydrocarbon contamination.

Acid resins are residues produced in a recycling process for used oils that was in use in the forties and fifties of the last century. The resin-like material is highly contaminated with mineral oil hydrocarbons, extremely acidic and co-contaminated with substituted and aromatic hydrocarbons, and heavy metals. To determine the potential for microbial biodegradation the acid resin deposit and its surroundings were screened for microbial activity by soil respiration measurements. No microbial activity was found in the core deposit. However, biodegradation of hydrocarbons was possible in zones with a lower degree of contamination surrounding the deposit. An extreme acidophilic microbial community was detected close to the core deposit. With a simple ecotoxicological approach it could be shown that the pure acid resin that formed the major part of the core deposit, was toxic to the indigenous microflora due to its extremely low pH of 0-1.

Biodegradation, Environmental↗