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To study the change of the aerobic granules' microbial community in the present of antibiotics, ampicillin (AMP) was selected as a model component. With acetate as carbon source, different concentrations of AMP (5, 10 and 15 mg L −1 ) were applied to the inflow intermittently and the results showed that the stability of the aerobic granules was maintained below 10 mg L −1 AMP. Simultaneously, under exposure to 5 and 10 mg L −1 AMP, the COD removal efficiency in the batch reactors remained at 86% and AMP was degraded almost completely with a removal efficiency of 97%. However, the EPS concentration and dehydrogenase activity decreased constantly with increasing AMP dosage. High-throughput sequencing analysis revealed that Proteobacteria was the most prominent phylum in the whole experiment and contributed to the degradation of AMP. The percentages of Azoarcus and Mycoplana increased at 10 mg L −1 AMP. In addition, Hydrogenophaga and Enterococcus played a key role in the microbial metabolism. [ABSTRACT FROM AUTHOR]

The effects of applying sewage sludge (SS) to agricultural soil (at low rate of 22.5, LRS, and at high rate of 45 t ha−1dry basis, HRS) were monitored over a 120-d experimental period. Total organic carbon (TOC), water-soluble organic carbon (WSOC), alkali-soluble phenols, basal respiration, specific enzyme activity, dehydrogenase activity (DH-ase), metabolic potential (MP) and FDA-hydrolytic activity (FDA) were strongly increased by both rates of SS applications. In the SS amended soil, about 70% of the organic C added with the material remained at the end of the experiment. Basal respiration increased with increasing SS doses. The specific enzyme activity and the MP indicate an increase in the enzyme activity in soil. The addition of SS led to higher values than the control of all the tested parameters up to the end of the experimental period. The antioxidant capacity (trolox equivalent antioxidant capacity, TEAC) was influenced by SS addition only when applied at HRS. After 120 days only HRS value of TEAC (5.13 mM g−1) was higher than control (4.09 mM g−1). The pattern of TEAC did not enable any link to be established between antioxidant capacity and both alkali-soluble phenols and basal respiration in soil. [ABSTRACT FROM PUBLISHER]

In the biological treatment of the industrial wastewater, low temperatures and low carbon nitrogen ratios (C/N) are great challenges. In this research, one conventional multistage A/O membrane bioreactor (MMBR) and one electric-coagulation multistage A/O membrane bioreactor (ECMMBR) were established to investigate the effect of Fe-C electrodes on the biodegradability of the activated sludge when treating the low C/N industrial wastewater. Results showed that the Fe electrode enhanced nitrogen transformation and the biodegradation of COD and volatile phenols. The dehydrogenase activity, the NH 4 + -N and NO 2 − -N degradation rate of the unit sludge were higher in ECMMBR. Moreover, results from high throughput sequencing analysis revealed that ECMMBR may improve Chao and Shannon indices. ECMMBR improved the relative abundance of Luteimonas and Trueperaceae , which were cold-resistant and hydrocarbon-bearing microorganisms. This study demonstrated that the electric field and iron ions may improve the biodegradability of activated sludge, dehydrogenase activity and nitrogen transformation rate and enrich the richness and the diversity of communities in the activated sludge at low temperatures. The research provided a valuable technical method for the biodegradation of the low carbon and high ammonia industrial wastewater. [ABSTRACT FROM AUTHOR]

Bacteria able to produce biosurfactants can use petroleum-based hydrocarbons as a carbon source. Herein, four biosurfactant-producing Pseudomonas aeruginosa strains, isolated from oil-contaminated saline soil, were combined to form a bacterial consortium. The inoculation of the consortium to contaminated soil alleviated the adverse effects of salinity on biodegradation and increased the rate of degradation of petroleum hydrocarbon approximately 30% compared to the rate achieved in non-treated soil. In saline condition, treatment of polluted soil with the consortium led to a significant boost in the activity of dehydrogenase (approximately 2-fold). A lettuce seedling bioassay showed that, following the treatment, the soil's level of phytotoxicity was reduced up to 30% compared to non-treated soil. Treatment with an appropriate bacterial consortium can represent an effective means of reducing the adverse effects of salinity on the microbial degradation of petroleum and thus provides enhancement in the efficiency of microbial remediation of oil-contaminated saline soils. [ABSTRACT FROM AUTHOR]

This study investigated the distribution of ion contents and microorganisms during the electro-bioremediation (EK–Bio) of petroleum-contaminated saline soil. The results showed that soil ions tend to accumulate around the electrodes, and the concentration was correlated with the distance from the electrodes. The average soil ion content was 7.92 g/kg around the electrodes (site A) and 0.55 g/kg at the furthest distance from the electrodes (site B) after 112 days of treatment, while the initial average content was 3.92 g/kg. Smooth linear (R2= 0.98) loss of soil ions was observed at site C, which was closer to the electrodes than site B, and had a final average soil ion content of 1.96 g/kg. The dehydrogenase activity was much higher in EK–Bio test soil than in the Bio test soil after 28 days of treatment, and followed the order: site C > site B > site A. However, the soil dehydrogenase activity dropped continuously when the soil ion reached very high and low concentrations at sites A and B. The soil microbial community varied in sample sites that had different ion contents, and the soil microbial diversity followed the order: site C > site B > site A. The applied electric field clearly enhanced the biodegradation efficiency for soil petroleum contaminants. However, the biodegradation promotion effects were weakening in soils where the ion contents were extremely high and low (sites A and B). These results can provide useful information for EK–Bioremediation of organic-contaminated saline soil. [ABSTRACT FROM AUTHOR]

BACKGROUND Monoculture is used mostly in conventional agriculture, where a single crop is cultivated on the same land for a period of at least 12 months. In an organic and integrated growing approach, more attention is paid to plant-environment interactions and, as a result, diverse growing systems applying intercropping, catch crops, and green manure are being implemented. Thus, field experiments for evaluation of vegetable/faba bean full intercropping efficiency, in terms of vegetable and faba bean yield and protein content, were set up during two consecutive growing seasons (2014 and 2015). RESULTS Data obtained showed that the most efficient intercropping variants were cabbage/faba bean (cabbage yield 1.27-2.91 kg m−2, immature faba bean pods 0.20-0.43 kg m−2) and carrot/faba bean (carrot yield 1.67-2.28 kg m−2, immature faba bean pods 0.10-0.52 kg m−2), whilst onion and faba bean intercrop is not recommended for vegetable growing since it induces a very low onion yield (0.66-1.09 kg m−2), although the highest immature faba bean pod yield was found in the onion/faba bean intercropping scheme (up to 0.56 kg m−2). CONCLUSION Vegetable/faba bean intercropping can be used in practical horticulture for carrot and cabbage growing in order to ensure sustainable farming and environmentally friendly horticultural production. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A 2-year field experiment was conducted to study the influence of three planting methods (Happy Seeder, Straw Chopper + Zero Tillage, and Conventional tillage) and four nitrogen rates (control, 75, 100, and 125% of recommended nitrogen) on the chemical and biological properties of soil. The results revealed that after soybean harvest, dehydrogenase activity and population ofBradyrhizobiumsp. (LSBR 3) and plant growth promoting rhizobacteria (PGPR) were increased significantly in Happy Seeder sowing and Straw Chopper + Zero Tillage sowing than conventional sowing and population ofBradyrhizobiumsp. significantly increased up to the 100% nitrogen level. There was no significant effect of different planting methods on soil chemical properties. Organic carbon and available nitrogen were increased significantly with an increase in the nitrogen level up to 100% nitrogen (N). [ABSTRACT FROM AUTHOR]

Reutilization of treated wastewater (TWW) in agriculture has continued to grow, especially in areas prone to frequent drought periods. One of the major aspects derived from this practice is the addition of important amounts of organic carbon (OC) that could interfere with the fate of organic contaminants in soils. This study has evaluated the impact of irrigation with a secondary TWW and dissolved OC (DOC) solutions from sewage sludge in the dissipation of thiacloprid (THC), pendimethalin (PDM) and fenarimol (FEN) in an OC-poor agricultural soil under laboratory conditions. The effect on soil microbial activity was also assessed through the measurement of dehydrogenase activity. Biotic processes were the main responsible for the degradation of the three compounds. Results showed that while THC was rapidly degraded (DT 50 ≤ 5.5 d), PDM and FEN were moderately persistent in soil (DT 50 ≥ 93 d). Incubation with TWW did not modify the decay rate of the three pesticides, but initially inhibited soil biota. Solutions of DOC did not alter the dissipation of FEN, but contrasting effects were observed for THC and PDM. Low DOC concentrations (30 mg L −1 ) accelerated THC disappearance, a fact explained by stimulation of endogenous biota rather than by the presence of exogenous microorganisms from the solution. On the other hand, high DOC concentrations (300 mg L −1 ) had more influence on the activity of microorganisms at longer times, and showed a trend to enhance the disappearance of the moderately persistent PDM. [ABSTRACT FROM AUTHOR]

In organic farming the use of mineral fertilizers is highly restricted; hence biofertilizers are often used. The aim of the research was to investigate the effects of different fertilizers on soil microbial communities and enzymatic activity after conventional production. A field with potato cultivation under conversion to an organic system was established. The nitrogen organic fertilizer Bioilsa and two microbial biofertilizers - UGmax and EM - were used. The highest values of dehydrogenase activity (DHA) were observed in the soil where UGmax was used alone. Application of biofertilizers also caused an increase of DHA in variants with Bioilsa fertilizer. The differences in activity of phosphatase in relation to application of different biofertilizers were observed, but it was higher than in variants with Bioilsa. Application of Bioilsa had a positive effect on activity of acid and alkaline phosphatases, but probiotic EM reduced this positive effect. The total number of bacteria and actinobacteria was the highest in EM variants, not fertilized with Bioilsa. In the case of the fungal population no correlation with fertilization was noted. We conclude that biofertilizers can activate the microbial and enzymatic activity of the soil after intensive agriculture production and can neutralize the negative impact on these parameters of nitrogen fertilizer. [ABSTRACT FROM AUTHOR]

In the present study, quick-lime-based thermal-alkaline sludge disintegration (SD) under low temperature was combined with cryptic growth to investigate the excess sludge reduction efficiency in the sequencing batch reactor (SBR). The optimized condition of SD was as follows:T = 80℃, pH = 11,t = 180 min, and the SD rate was about 42.1%. With 65.6% of excess sludge disintegrated and returned to the SBR, the system achieved sludge reduction rate of about 40.1%. The lysis-cryptic growth still obtained satisfactory sludge reduction efficiency despite the comparative low SD rate, which suggested that disintegration rate might not be the decisive factor for cryptic-growth-based sludge reduction. Lysis-cryptic growth did not impact the effluent quality, yet the phosphorus removal performance was enhanced, with effluent total phosphorus concentration decreased by 0.3 mg/L (33%). Crystal compounds of calcium phosphate precipitate were detected in the system by Fourier transform infrared spectroscopy and X-ray diffraction, which indicated the phosphorus removal potential of SD using lime. Moreover, endogenous dehydrogenase activity of activated sludge in the lysis-cryptic system was enhanced, which was beneficial for sludge reduction. SD and cryptic growth in the present study demonstrates an economical and effective approach for sludge reduction. [ABSTRACT FROM PUBLISHER]

The variation of carotenoid and bacteriochlorophyll in photosynthetic bacteria (PSB) by high salinity stress (20–100 g L −1 ) was investigated. Results showed that PSB could grow in high salinity wastewater and the productions of two pigments were affected by the salinity significantly. Suitable salinity stress could enhance their productions while excessive salinity would impede the productions. When the NaCl concentration was 50 g L −1 , the PSB were stimulated continuously during the whole culture period, and the productions of carotenoid and bacteriochlorophyll were 1.17 and 1.45-fold of the control group. The variation of dehydrogenase activity indicated that high salinity changed the metabolic activity greatly, and the highest level of dehydrogenase activity appeared at 50 g L −1 NaCl condition. Mechanisms analysis showed that the variations of pigments and dehydrogenase were related to self-protection. At the same time, pollutants in high salinity wastewater were removed by PSB. The COD and NH 3 -N removals under 20–100 g L −1 NaCl concentration were around 33.5–66.1%. The biomass yields were over 0.2 mg-biomass (mg-COD-reduction) −1 under all situations and salinity benefitted the biomass yield. [ABSTRACT FROM AUTHOR]

Aim. Different factors were influence on physiology-biochemical activity of bacteria - components microbial preparations for plant-growth. The aim of this work was to study the influence of different factors on dehydrogenase activity of Azotobacter vinelandii IMV B-7076 - compound of the complex bacterial preparation Azogran. Methods. In this experimental work was used microbiological, biochemical, and statistical methods. Dehydrogenase activity was measured accordingly to the method is based on the reduction of 2.3.5-triphenyltetrazolium chloride (TTC) to red-colored triphenyl formazan (TF) in anaerobic conditions. Results. It was established, that the dehydrogenase activity of Azotobacter vinelandii IMV B-7076 reached its maximum value at cultivation in nutrient medium with 10 g/L of glucose, pH 9.0 and 28°C. It was shown, that at addition of the certain concentration of ions Ca2+ and Mg2+ into a nutrient medium the dehydrogenase activity of bacteria increased. However, ions Fe2+ inhibited this activity. Conclusion. It has been determined depending of dehydrogenase activity of Azotobacter vinelandii IMV B-7076 from different physico-chemical factors. It over under standing about properties this bacteria and help predict prognoses the perceptivity use of preparation Azogran in different agroecosystems. [ABSTRACT FROM AUTHOR]

Behavior of E. dissolvens under the exposure to weak direct current (DC) was investigated by using glucose as the sole carbon source. Continuous cultivation behavior of E. dissolvens under the exposure to weak direct current (DC) was investigated . Experimental results showed the electrolytic stimulation of the continuous culture, cell growth curve and glucose metabolic rate were significantly improve. After electrolytic stimulation for 10 hour, the specific dehydrogenase activity and glucose consumption were 2 and 1.8 fold as much as that determined in the absence of electric field. Owing to flowing of the culture medium, the cells by the DC application after the growth phase were better than the control. [ABSTRACT FROM AUTHOR]

Dehydrogenase activity (DHA) is an important indicator of heavy metal toxicity in contaminated soils. Different instances of DHA were determined using various substrates and which could affect the description of heavy metal toxicity. Currently, too few investigations have been done on selecting appropriate substrates. This study employed indoor simulation to determine soil DHA and its response to external cadmium (Cd) using two substrates (TTC and INT). Hormesis for DHA obtained using the TTC method (DHA-TTC) in low Cd concentration was observed which was quickly inhibited in high Cd concentration. While DHA obtained using the INT method (DHA-INT) decreased slowly when Cd concentration increased. The DHA-TTC and DHA-INT in soils at Cd concentration of 500 mg kg −1 decreased 86% and 53%, respectively, compared to the control. The dose-response relationship of Cd to DHA can be well simulated using the logistic model ( p < 0.01), which indicated DHA could be used to indicate soil Cd toxicity. Multiple stepwise regression analysis revealed that total organic matter (TOC) is the major factor influencing the toxicity of Cd to DHA-TTC, while TOC, pH and cation exchange capacity (CEC) are major factors influencing the toxicity of Cd to DHA-INT. The different responses of soil DHA-TTC and DHA-INT to Cd are due to the differences in electron transport chain characteristics between TTC and INT, as well as the influence of soil properties. Although both DHA-TTC and DHA-INT can monitor soil Cd contamination, DHA-INT is recommended as a superior bio-indicator to indicate and assess contamination of Cd in soil. [ABSTRACT FROM AUTHOR]

A pot culture experiment in rice was conducted to study the effect of pre and post emergence herbicides on microbial biomass carbon and dehydrogenase activity in soils. Results indicated that the herbicides had negative effect on microbial biomass carbon. Dehydrogenase activity also showed a decline due to the application of herbicides, but to a lesser magnitude than microbial biomass carbon. The adverse effect was pronounced only at 15 days after application of herbicides and followed the order viz., pendimethalin > bispyribac-sodium > oxyfluorfen > cyhalofop-butyl. The adverse effects were of lower magnitude in the soils of high organic matter content. [ABSTRACT FROM AUTHOR]

Membrane bioreactor (MBR) is an attractive sewage treatment technology but the major weakness remains in membrane fouling. Nowadays, magnetic activated sludge process with magnetic particle addition has been extensively investigated for membrane fouling mitigation due to the excellent magnetic bio-effect. However, the bioeffect is still limited and further study to enhance the fouling control is needed. Herein, the starch-coated magnetic particles (M s P) were fabricated and utilized to alleviate membrane fouling and enhance the treatment performance for low carbon/nitrogen municipal wastewater treatment. The M s P addition in MBR can effectively mitigate the membrane fouling which might be due to the magnetic bio-effect and enhanced bioflocculation, leading to the lower soluble microbial product (SMP) concentration from 17.3 ± 1.7 to 13.1 ± 0.7 mg L−1, higher microbial dehydrogenase activity from 234.65 ± 11.21 to 430.57 ± 39.48 mgTF gVSS−1h−1, bigger sludge particle size and more extracted extracellular polymer substances (EPS) secretion in the bulk sludge. Additionally, M s P particle can facilitate to form an aerobic and anoxic microenvironment, which is conducive to improve the nitrogen removal for low carbon/nitrogen municipal wastewater treatment. Microbial diversity analyses revealed that M s P addition enriched Flavobacterium sp , leading to more EPS secretion and therefore enhance the hydrophobic property and aggregation ability of sludge flocs to mitigate membrane fouling. Rhodobacter sp was also accumulated, indicating better denitrification process for total nitrogen removal. This study provided evidence for the efficiency of adding M s P to MBR in order to suppress membrane fouling and improve nitrogen removal for low carbon/nitrogen municipal wastewater treatment. [Display omitted] • M s P addition in MBR can further mitigate the membrane fouling compared with MP. • Higher TN removal efficiency was obtained for low C/N wastewater with M s P addition. • M s P addition can enhance bioflocculation and form an aerobic-anoxic micro-environment. • The bulk sludge was changed due to magnetic bio-effect and enhanced bioflocculation. • Flavobacterium and Rhodobacter were accumulated with M s P addition. [ABSTRACT FROM AUTHOR]

The main objective of this study was to determine changes in soil dehydrogenase activity in natural macro aggregates development along a slope in forest soils. This study was carried out in Kocadag, Samsun, Turkey. Four landscape positions i.e., summit, shoulder backslope and footslope, were selected. For each landseape position, soil macro aggregates were separated into six aggregate size classes using a dry sieving method and then dehydrogenase activity was analyzed. In this research, topography influenced the macroaggregate size and dehydrogenase activity within the aggregates. At all landscape positions, the contents of macro aggregates (especially > 6.3 mm and 2.00–4.75 mm) in all soil samples were higher than other macro aggregate contents. In footslope position, the soils had generally the higher dehydrogenase activity than the other positions at all landscape positions. In all positions, except for shoulder, dehydrogenase activity was greater macro aggregates of

Activity of soil dehydrogenase (DHA) was measured in the mineral soil in a forest stand of 15 to 16-year-old Scots pine (Pinus sylvestris L.) from geographically diverse populations, as an indicator of biological activity of soil microorganisms, in a provenance experiment in Poland. The pine populations originated from six European countries (Sweden, Russia, Latvia, Poland, Germany, France) and differed widely in aboveground biomass and productivity. Soil DHA during two growing seasons showed pronounced seasonal variability, which was significantly related to the fine root concentration of nonstructural carbohydrates. Higher DHA was found in soil under canopies of the central and southern European populations than in those from more northern parts of the Scots pine range. Significant positive correlation between soil DHA and aboveground tree biomass suggest that these patterns most likely resulted from differences in carbon dynamics and productivity among populations.

The effects of rimsulfuron a sulfonylurea herbicide on the growth and activity of soil microorganisms under laboratory conditions was investigated in two soils. The application rates were: 0.2, 2.0 and 20.0 mg a.i kg-1 soil. The lowest concentration tested was the label rate (0.2 mg a.i kg-1), and the other two were ten and hundred timeshigher. No adverse effects on microbiological processes were observed for the label rate. Decrease in microbial biomass carbon, dehydrogenase activity, fungi and bacteria in comparison with untreated control, were found at higher rates. The magnitude of these effects were generally slight and transitory.

The effects of metals (Сu, Pb, Ni, Cr, Cd) and fungicide alto-super on dehydrogenase activities of indigenous microflora of grey forest soil and laboratory culture Bacillus pumilus КМ-21 were studied. It was determined that the putting of the metals into soil caused the dose-effect inhibition of dehydrogenase activities of indigenous microflora of soil and dehydrogenase activities Bacillus pumilus КМ-21 estimated in eluate and contact tests. On the base of the established metal concentration causing the 50% inhibition on dehydrogenase activity, it was revealed that the contact test was more sensitive in comparison with eluate test. Cose relation between the alteration in activities of microbial culture (contact test) and indigenous microflora was shown. It allowed to recommend the contact test for estimation of the soil contamination with toxic compounds.

The toxicity of phenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 2-chlorophenol, 4-chlorophenol, 4-bromophenol and 3,5-dimethylphenol on Pseudomonas, Bacillus and Escherichia species isolated from petroleum refinery wastewater was assessed via inhibition of dehydrogenase enzyme activity. At low concentrations, 2-nitrophenol, 2-chlorophenol, 4-chlorophenol, 4-bromophenol and 3,5-dimethylphenol stimulated dehydrogenase activity and at sufficient concentrations, phenolic compounds inhibited dehydrogenase activities. Generally, phenol is less toxic than substituted phenols. Estimations of the degree of inhibition/stimulation of dehydrogenase activities showed significant dose-dependent responses that are describable by logistic functions. The toxicity thresholds varied significantly (P < 0.05) among the bacterial strains and phenolic compounds. The median inhibitory concentrations (IC50s) ranged from 4.118 ± 0.097 mg.L-1 for 4-nitrophenol against Pseudomonas sp. DAF1 to 1407.997 ± 7.091 mg.L-1 for phenol against Bacillus sp. DISK1. This study suggested that the organisms have moderate sensitivity to phenols and have the potential to be used as indicators for assessment of chemical toxicity. They could also be used as catalysts for degradation of phenols in effluents.

Toxicity of zinc to Pseudomonas, Escherichia, Proteus, Bacillus and Arthrobacter species isolated from a tropical river and petroleum refinery effluent was assessed using TTC-dehydrogenase activity (DHA) inhibition test. At sufficient concentrations, zinc is toxic to these bacterial cells, and the exposure of the cells to zinc ion resulted in repression of dehydrogenase activity. The patterns of these toxic effects can be mathematically described with logistic dose-response models and in a manner similar to the non-competitive inhibition of enzymes. The threshold concentration above which toxic effect is observed ranged from 0.008 mM for Pseudomonas sp. DAF1 to 0.364 mM for Proteus sp. PLK2. The coefficients of inhibition Ki correlated with the IC50 and indicate that zinc toxicity is dependent on the organism. The Ki and toxicity threshold values predicted from the equations are comparable and are suitable indicators for kinetic analyses of zinc toxicity against bacteria.

The Casa de Fresco de Sanches Baena is located in Vila Viçosa (Southeast Portugal) and is a small semi-underground building constructed in a garden over a well and used as a cool refreshing place by the owners. The frescoes that cover the ceilings and the walls present rich mythological scenes together with musical angels, shells, porcelain and other decorative elements, which make them an especially rich and unusual example of this art form. The paintings possess an intense polychromy suggesting the use of a rich palette comprised of different pigments to obtain various colours and hues. Unfortunately, due to partial abandonment and lack of repair the paintings are in an advanced state of degradation exhibiting partial detachment of paint layers and mortars, salt efflorescence and abundant biological colonisations. This work reports the study of the frescoes to allow the identification of the different microorganism populations and to assess their role in the deterioration of these paintings. For the microorganism sampling, sterile cotton buds and stylets were used and the biological materials collected in sterile recipients. The microbiological study by optical microscopy and scanning electron microscopy allowed the isolation of 34 fungi strains and 32 bacterial strains in the four painted panels that compose the frescoes. The predominant bacterial strains were the Gram+ and Gram- strains from the genera Bacillus and Pseudomonas, respectively. As to the fungi populations, the dominant strains identified were from the genera Cladosporium spp. and Penicillium spp. The microbial activity in the 4 panels was assessed by enzymatic essays, namely, dehydrogenase (DHA). The results showed that the decayed areas of the painting present higher dehydrogenase activity and therefore this enzyme seems to be a good indicator of biodegradation.

Excessive use of plant growth stimulants and pesticides is currently a considerable problem, especially in agriculture, horticulture, and arboriculture. Understanding the impacts of these compounds and their combinations on non-target organisms is crucial to minimize unintended consequences, while maintaining their use in plant protection. The aim of this study was to test how long-term spraying with different solutions of natural biostimulator chitosan, synthetic fungicide Switch 62.5 WG, and their combinations affects the physiology of epiphytic lichen Xanthoria parietina naturally occurring in fruit orchards and farmlands. We showed that fungicides composed of fludioxionil and cypronidil, as well as the combined use of such fungicides together with chitosan, can cause the considerable impairment of lichen physiology, and these disturbances relate to both algal and fungal partners of the symbiotic association. This negative effect was especially visible in the loss of cell membrane integrity, the high level of membrane lipid peroxidation, and changes in chlorophyll fluorescence parameters on the last day of the experiment. The combined use of these agents also leads to clear disturbances in the functioning of the mitochondrial respiratory chain, which was manifested by increased NADH dehydrogenase activity, while the use of these compounds separately led to a decrease in the activity of this enzyme. We concluded that the regular use of these agents in fruit tree cultivation may cause serious ecological consequences for epiphytic lichen communities as a result of the death of lichen thalli. This study suggests that the impact of some plant protection agents, both individually and in combinations, merits further attention in terms of their impact on non-target fungi. [Display omitted] • Combined usage of synthetic fungicides and chitosan may impair lichen physiology. • The disturbances relate to both the algal and fungal partner of symbiotic association. • Increased membrane lipid peroxidation and cell membrane damage were observed. • Disturbances in the functioning of mitochondrial respiratory chain was recognized. • Plant protection agents deserve attention due to their impact on non-target fungi. [ABSTRACT FROM AUTHOR]

This study was aimed to investigate the effect of moderate pressure on organic matter removal efficiency and microbial population of activated sludge treating saline wastewater. The activated sludge was cultivated with a gradual increase of salt concentrations under gage pressure of 0.3 MPa for 71 days. Microbial diversities of activated sludge sampled in different stages of domestication were investigated by Illumina sequencing technology. Results showed that pressurized aeration could improve the treatment efficiency and the dehydrogenase activity (DHA) of activated sludge, especially at high salinity (35, 50 g NaCl L −1 ). Bacterial richness and community diversity of activated sludge in the pressurized reactor were significantly higher than those in the control reactor. Microbial population structures were quite different between the two reactors. More species originating from fresh wastewater biological treatment process would survive and remain in pressurized activated sludge. [ABSTRACT FROM AUTHOR]

The objectives of this study were to investigate the mutual effect of the PAHs fluorene and pyrene on their respective biodegradation and dissipation processes in an agricultural soil, and to determine the effect of hydroxypropyl-β-cyclodextrin (HPBCD), used to increase the bioavailability of PAHs, on such processes. Fluorene dissipation was primarily due to abiotic processes, although a small contribution from biodegradation was also observed. Therefore, fluorene dissipation did not increase with HPBCD and its presence did not significantly alter the dehydrogenase activity. In contrast to fluorene, pyrene dissipation depended primarily on biotic factors, with endogenous soil microorganisms capable of degrading pyrene, with large increases in dehydrogenase activity. HPBCD increased biodegradation rate of pyrene. The co-contamination of soil with both PAHs did not affect fluorene evolution, but significantly inhibited pyrene biodegradation. The different abilities of soil bacterial consortia to catabolize these PAHs are discussed. Additionally, the possibility that the abiotic loss of fluorene through volatilization had a significant effect on the microbial community biodegradation of both fluorene and pyrene is examined. [ABSTRACT FROM AUTHOR]

An incubation experiment was conducted to evaluate the effects that three types of biomass ash, each applied at two doses, exert on the nutrient availability in a calcareous soil. The application of the ash from dry olive cake or greenhouse vegetable wastes significantly increased soil ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA)-extractable phosphorus (P), potassium (K), sodium (Na), copper (Cu) and zinc (Zn) as well as exchangeable and non-exchangeable K and Na. Wood ash was effective only for increasing soil ABDTPA-extractable Zn and Cu. By contrast, the three types of biomass ash hardly increased soil ABDTPA-extractable Fe or Mn. The high content in carbonate of the soil appears to minimize the potential of the ash to increase the micronutrients availability, which shortened with longer incubation time. Soil ABDTPA-extractable heavy metals were not detected in the different treatments tested. Other parameters of the soil, as pH and organic carbon, were scarcely affected by the ash, while conductivity and dehydrogenase activity increased. [ABSTRACT FROM AUTHOR]

The experimental plots used in the study were located in the middle forest zone (elevation: 900-950 m a.s.l.) on two nappes of the flysch Carpathians in southern Poland. The aim of this study was to assess the effects of serpentinite in combination with nitrogen, phosphorus, and potassium fertilizers on selected chemical properties of the soil and activity of dehydrogenase and urease in the studied soils. All fertilizer treatments significantly enriched the tested soils in magnesium. The use of serpentinite as a fertilizer reduced the molar ratio of exchangeable calcium to magnesium, which facilitated the uptake of magnesium by tree roots due to competition between calcium and magnesium. After one year of fertilization on the Wisła experimental plot, the pH of the Ofh horizon increased, while the pH of the mineral horizons significantly decreased. Enrichment of serpentinite with nitrogen, phosphorus, and potassium fertilizers stimulated the dehydrogenase activity in the studied organic horizon. The lack of a negative effect of the serpentinite fertilizer on enzyme activity in the spruce stand soil showed that the concentrations of the heavy metals added to the soil were not high enough to be toxic and indicated the feasibility of using this fertilizer in forestry. [ABSTRACT FROM AUTHOR]

We investigated the effects of several tree species on dehydrogenase and urease activities in soils derived from two different parent materials (glaciofluvial sand and loess) in forested areas in southern Poland. We hypothesized that coniferous forests (pine, spruce) alter the soil cation exchange capacity (CEC) and decrease soil pH and, therefore, might decrease soil enzyme activities compared with broadleaf species growing on similar soils. Eight paired plots (12 × 12 m) were established on glaciofluvial sand in pine ( Pinus sylvestris) + oak ( Quercus robur) and spruce ( Picea abies) + pine stands, as well as on loess-derived soils: beech ( Fagus sylvatica) + pine and hornbeam ( Carpinus betulus) + pine stands. Each plot was a 4 × 4 m grid with 16 sampling points. In soil samples pH, soil texture, and organic carbon, nitrogen, base cation contents, dehydrogenase and urease activities were determined. On both parent materials, the soil pH was lower under coniferous species than under broadleaf species. The acidifying effect of tree species on sandy soil was in the order of spruce = pine > oak, while that on loess was pine > beech > hornbeam. Hornbeam and oak increased the soil pH and stimulated enzyme activity in the soil. The content of fine fraction enhanced potential enzyme activities in soils, thus the loess soils had greater dehydrogenase and urease activity. The results suggest that pine stores more soil organic C in association with silt increasing the pool of stabilized soil organic C. [ABSTRACT FROM AUTHOR]

The toxicity of water-receiving bodies, the effluent and other treatment stages in wastewater treatment plants has recently been of interest to the public due to the lack of a regulated toxicity-based index for wastewater discharge in China. This study aimed to evaluate the conventional pollution parameters and toxicities of wastewaters collected at different treatment stages from a pharmaceutical industrial park wastewater treatment plant through dehydrogenase activity (DHA) and bioluminescent bacteria ( Vibrio qinghaiensis ) tests. The results of an analysis of conventional parameters indicated that the total suspended solids (TSS), chemical oxygen demand (COD), total nitrogen (TN), ammonia nitrogen (NH 3 N), and total phosphorus (TP) were largely removed after various treatments. However, the TN, NH 3 N and COD still exceeded the regulated standards. The tested pharmaceutical park effluents were mainly polluted with organic pollutants and nitrogenous. The toxicity test results indicated that the toxicities could be markedly reduced after treatment, with the toxicities of two out of the six effluent samples at different treatment stages being greater than the influent toxicity. Spearman’s rank correlation coefficients indicated a significantly positive correlation between the toxicity values obtained using the DHA and Vibrio qinghaiensis tests. Compared with the DHA measurement, the Vibrio qinghaiensis test was faster and more sensitive. Meanwhile, the toxicity indicators were significantly and positively correlated with the TSS, TN, TP and COD concentrations. These results may aid the understanding of the toxicity of pharmaceutical industrial park wastewaters and toxicity removal using the treatment techniques that are currently utilized in China. [ABSTRACT FROM AUTHOR]

Evaluating the impact of cultivation systems for improving the management of agricultural soil is difficult. Traditional ploughing cultivation can contribute to soil erosion. An alternative to conventional tillage is conservation tillage. The aim of our study was to determine the influence of different cultivation systems on the biochemical and biological activity of soil under sugar beets. The conventional tillage treatment with soil ploughing to a depth of 35 cm was the control treatment (CT). For comparison, we analysed the following conservation tillage systems consisting of shallow or deep-soil ripping: 1. Tillage to a depth of 35 cm and sowing into stubble mulch (MS35). 2. Tillage to a depth of 15 cm and sowing into stubble mulch (MS15). 3. Tillage to a depth of 15 cm and sowing into white mustard mulch (MG). 4. Strip-till on stubble mulch to a depth of 25 cm and instantaneous beet seed sowing (STS). 5. Strip-till to a depth of 25 cm on white mustard mulch and instantaneous beet seed sowing (STG). The soil samples that were used for biochemical and microbiological analyses were collected during four terms in each year, which coincided with the four consecutive stages of the development of sugar beets. During both years of research we obtained results concerning the influence of different soil cultivation methods on the number of selected groups of soil microorganisms and the enzymatic activity under sugar beets. In 2012-13 the highest bioactivity was noted in the period of the greatest demand of sugar beets for nutrients, at the phase when the rows of plants were closing in. At that time the content of actinobacteria in the soil collected from the sites where STS had been applied was 42% greater than in the soil from the ploughing cultivation system. Apart from that, in this same term, whenever conservation tillage was applied the activity of dehydrogenases and phosphatases always increased. [ABSTRACT FROM AUTHOR]

A field experiment was conducted at Indira Gandhi Krishi Vishwavidyalaya, Raipur, Chhattisgarh (C.G.), India, during rabi season of 2013-14 to find out effective herbicide in chickpea. Results revealed that among the herbicidal treatments, post-emergence application of metribuzin @ 250 g a.i. ha-1 and early post-emergence application of oxyfluorfen @ 125 g a.i. ha-1 has recorded phytotoxicity on chickpea plants at 3, 7 and 10 days after spraying of herbicides and resulted in 62.26 and 53.19% reduction in yield, respectively, over hand weeding twice. The significantly minimum dehydrogenase activity was also observed under post-emergence application of metribuzin @ 250 g a.i. ha-1 and early post-emergence application of oxyfluorfen @ 125 g a.i. ha-1. Whereas, among the herbicides, pre-emergence application of pendimethalin @ 1000 g a.i. ha-1 resulted in significantly higher dehydrogenase activity of experimental field. Hand weeding twice at 25 and 45 DAS and pre-emergence tank mix application of oxyfluorfen+metribuzin @ 125+350 g a.i. ha-1 were most appropriate in reducing the density and dry weight of weeds with the weed control efficiency of 90.43 and 74.31%, respectively. Further, the significantly higher yield attributes, seed yield, stover yield and harvest index registered under hand weeding twice at 25 and 45 DAS, followed by the treatment of oxyfluorfen+metribuzin @ 125+350 g a.i. ha-1 as pre-emergence. Net return and B:C ratio was also recorded maximum under pre-emergence tank mix application of oxyfluorfen+metribuzin @ 125+350 g a.i. ha-1. [ABSTRACT FROM AUTHOR]

Electrochemical degradation of 2,4-dichlorophenol (2,4-DCP) in aqueous solution has been studied by a dualcathode oxidation system (DOS), in which a gas-diffusion electrode was used to produce H2O2 in situ by oxygen reduction, a graphite cathode was employed to accelerate the reduction of Fe3+ and a Ti/SnO2-Sb2O5- IrO2 anode was used for the anodic oxidation (AO) of organics. It is shown that both electro-Fenton oxidation and AO account for the degradation of 2,4-DCP in this process. Comparative degradation showed that DOS could present a more rapid removal of 2,4-DCP compared with the single-cathode oxidation system. When -0.70 and -0.10V were applied to the gas-diffusion cathode and the graphite cathode, respectively, the degradation of 2,4-DCP solution (100mg/L) with 0.15mM Fe2+ at pH 3.0 for 240min yielded 80% total organic carbon removal and a mineralization current efficiency of 20%. The effect of DOS treatment on the toxicity reduction was evaluated by the dehydrogenase activity (DHA) of activated sludge. It was found that DHA value became greater via the treatment in contrast with the DHA value of untreated solution. This work suggests that DOS might present an alternative for the treatment or the pretreatment of effluents containing chlorophenols. [ABSTRACT FROM AUTHOR]

Effects of three different nutrient loadings (low nutrient loading, medium nutrient loading and high nutrient loading, denoted as LNS, MNS and HNS, respectively) on the structure and functions of algal biofilm using Anabaena flos-aquae were investigated using synthetic wastewater. Nutrients removal efficiencies, biofilm thickness, microalgae dehydrogenase activity (DHA) and exopolysaccharide (EPS) productions were examined. Results showed that the changes of nutrient concentration were insignificant after 4 days of experiment for the case of HNS condition; 9 days for the case of MNS condition, and 6 days for the case of LNS condition, respectively. The biofilm thickness, nutrient removal efficiencies, algae DHA and EPS productions increased with the increase of nutrient loadings in synthetic wastewater. For the case of HNS condition, the microalgal biofilm exhibited the best performance in terms of C, N and P removal efficiencies, reaching the removal rates of 68.45, 3.56 and 1.61 mg∙L-1∙d-1 for C, N, P, respectively. This was likely because, fact with the high nutrient loading, the high biological activity could be achieved, thus resulting in high nutrient removals. The thickness of the biofilm in HNS condition was 75 µm, which was closely related to EPS production. DHA and EPS concentrations were 7.24 and 1.8 × 10-2 mg∙mm-2, respectively. It was also shown that apart from the nutrient loading, the structure and functions of microalgal biofilm were also influenced by other factors, such as illumination and temperature. [ABSTRACT FROM AUTHOR]

Intensive crop over-fertilization is causing the diffuse contamination of superficial and ground-waters by nitrates in many Mediterranean areas. At the same time this practice is also damaging the soil in the long-term. In this work the feasibility of using composts as total or partial substitutes for conventional inorganic fertilization (CIF) was evaluated in two successive crops of lettuce ( Lactuca sativa L.), one of the most consumed vegetables in Europe. The aim was to offer alternative agricultural practices that are more environmentally friendly. Treatments consisting of various rates of inorganic and organic fertilizers (composts) were assayed in quadruplicate on a sandy loam soil classified as Haplic Calcisol in Southern Spain. Macro- and micronutrients and heavy metal concentrations were analysed in soil and plant leaves. Parameters such as soil basal respiration (BR), microbial biomass C (C mic ) and dehydrogenase (DHA) and hydrolase activities, indicators of soil microbial abundance and activity, were also determined after each crop. After the second lettuce crop, certain physical soil properties such as aggregate stability and soil water holding capacity were also determined. In the first crop lettuce yields in the compost-treated soils did not significantly (p≤ 0.05) differ from the yields of CIF-treated soils. In the second crop, however, lettuce yields were higher in organically treated soils than in soils receiving only inorganic fertilization. Organic fertilizers were able to supply sufficient nutrients to achieve similar yields as those obtained with additional inorganic fertilizer. After the second crop, organically treated soils also showed higher C, N, P concentrations and higher C mic , BR and DHA than soils receiving conventional inorganic fertilization as well as improved physical conditions (a higher percentage of stable soil aggregates and a greater water holding capacity). Also after the second lettuce crop, compost-treated soils showed significantly higher β-glucosidase and phosphatase activity than CIF-treated soils. Furthermore, lettuces grown in compost-treated soils showed significantly lower leaf nitrate concentration than lettuces grown in soil receiving CIF, thus reducing the potential toxicological risks associated with consuming nitrate-rich foods. Moreover, compost fertilization did not increase the concentration of heavy metals in lettuce leaves. Results confirm that manure and sewage sludge composts can be used as an alternative to inorganic fertilization in lettuce crop cultivation, leading to similar or even higher yields and reducing nutrient-leaching risks, while improving soil chemical, physical and microbiological properties. [ABSTRACT FROM AUTHOR]

Dehydrogenase activity is frequently used to assess the general condition of microorganisms in soil and activated sludge. Many studies have investigated the inhibition of dehydrogenase activity by various compounds, including heavy metal ions. However, the time after which the measurements are carried out is often chosen arbitrarily. Thus, it can be difficult to estimate how the toxic effects of compounds vary during the reaction and when the maximum of the effect would be reached. Hence, the aim of this study was to create simple and useful mathematical model describing changes in dehydrogenase activity during exposure to substances that inactivate enzymes. Our model is based on the Lagergrens pseudo-first-order equation, the rate of chemical reactions, enzyme activity, and inactivation and was created to describe short-term changes in dehydrogenase activity. The main assumption of our model is that toxic substances cause irreversible inactivation of enzyme units. The model is able to predict the maximum direct toxic effect (MDTE) and the time to reach this maximum (T). In order to validate our model, we present two examples: inactivation of dehydrogenase in microorganisms in soil and activated sludge. The model was applied successfully for cadmium and copper ions. Our results indicate that the predicted MDTE and T are more appropriate than EC and IC for toxicity assessments, except for long exposure times. [ABSTRACT FROM AUTHOR]

Membrane fouling alleviation by addition of poly dimethyl diallyl ammonium chloride (PDMDAAC) and magnetic powder (Fe 3 O 4 ) was investigated. It was found that magnetic powder associated with PDMDAAC had a good performance on mitigation of membrane fouling, improvement in dehydrogenase activity and enhancement of biomass growth. The optimal dose of PDMDAAC was determined by using constant pressure dead-end filtration unit. Maximum permeate flux was attained at 400 mg/L of PDMDAAC addition. Continuous experiment was conducted in a submerged membrane bioreactor (MBR) system and biomass parameters such as soluble microbial products (SMP), extracellular polymeric substances (EPS), dehydrogenase activity, zeta potential, and capillary suction time (CST) were analyzed. Best results were obtained with a combination of 120 mg/L of magnetic powder and 400 mg/L of PDMDAAC. This study results demonstrated that PDMDAAC played a major role in SMPc and EPSc reduction, whereas magnetic powder had better performance in decreasing SMPc and EPSp. [ABSTRACT FROM AUTHOR]

Development of soil microbial and soil fauna communities is a key factor in the soil forming process at reclaimed post-mine sites. The objective of this study was to determine the influence of reclaimed mine soil (RMS) properties (texture, pH, total organic carbon (TOC) and total nitrogen (TN)) and planted tree species on soil biological activity (dehydrogenase activity (DHA), microbial biomass carbon (MBC), enchytraeids ( Enchytraeidae ) and earthworm ( Lumbricidae ) communities). Research sites were located in southern Poland on an afforested sand mine pit (Szczakowa) and a sulphur mine spoil heap (Piaseczno). Study plots were arranged in pure tree stands of pine, larch, oak, birch and alder with 25- to 35-year-old trees growing on different RMS substrates: quaternary sands; quaternary loamy sands and loams; neogene clays; and mixed quaternary sands and neogene clay. Microbial biomass carbon depended mainly on the texture, TOC and TN content in the uppermost soil layer, whereas DHA was associated with the fine root annual increment. Earthworm biomass was significantly correlated with clay content, pH and TOC in the uppermost organic soil layers. Among planted tree species, black alder clearly altered soil microbial parameters, biomass and density of earthworms. The strongest effect on DHA was noted under birch trees. Among the studied tree species, deciduous trees (birch, alder and oak) had a greater impact on soil biological properties compared to coniferous trees (pine and larch). [ABSTRACT FROM AUTHOR]