Continuous in-situ measurement of free extracellular enzyme activity as direct indicator for soil biological activity

Levakov, Ilil; Ronen, Zeev; Siebner, Hagar; Dahan, Ofer

doi:10.1016/j.soilbio.2021.108448

Cited by 17 publications

(7 citation statements)

References 73 publications

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“…Soil enzymes are an important indicator of soil biological activity, and all biochemical activities in soil are performed under the action of soil enzymes ( Utobo and Tewari, 2015 ; Nannipieri et al, 2018 ). Soil enzyme activity is influenced by soil temperature, soil nutrients, microbial community, fertilization, and other factors ( Cheng et al, 2013 ; Díaz et al, 2021 ; Levakov et al, 2021 ; Tan et al, 2021 ). The activities of nitrogen cycle enzymes such as urease, protease, glutaminase, and catalase varied significantly under different nitrogen fertilizer treatments ( Cao et al, 2014 ; He et al, 2021 ; Li et al, 2021b ).…”

Section: Discussionmentioning

confidence: 99%

Effects of Temperature and Nitrogen Application on Carbon and Nitrogen Accumulation and Bacterial Community Composition in Apple Rhizosphere Soil

Zhang

Phillip

et al. 2022

Front. Plant Sci.

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Malus sieversii grows on the slopes of the Tianshan Mountains in Xinjiang where the difference in daily temperature is significant. In recent years, the rhizosphere soil health of Malus sieversii has been severely impacted by anthropogenic disturbance and pathogenic infestation. The soil nutrient content and soil microorganism diversity are the main components of soil health. Low temperature has negative effects on soil bacterial community structure by inhibiting the accumulation of carbon and nitrogen. However, the effects of temperature and nitrogen application on soil carbon and nitrogen accumulation and the bacterial community composition in the rhizosphere soil of Malus sieversii are unclear. We set two temperature levels, i.e., low temperature (L) and room temperature (R), combined with no nitrogen (N0) and nitrogen application (N1) to explore the response of plant carbon and nitrogen uptake, rhizosphere soil carbon and nitrogen accumulation and bacterial community composition to temperature and nitrogen fertilization. At the same temperature level, plant 13C abundance (P-Atom13C), plant 15N absolute abundance (P-Con15N), soil 15N abundance (S-Atom15N) and soil urease, protease and glutaminase activities were significantly higher under nitrogen application compared with the no-nitrogen application treatment. The bacterial community diversity and richness indices of the apple rhizosphere soil in the N1 treatment were higher than those in the N0 treatment. The relative abundances of Actinobacteria, Rhodopseudomonas, and Bradyrhizobium were higher in the LN1 treatment than in the LN0 treatment. Redundancy analysis (RDA) showed that plant 13C absolute abundance (P-Con13C) and plant 15N absolute abundance (P-Con15N) were the main factors affecting the soil bacterial community composition. In summary, Nitrogen application can alleviate the effects of low temperature stress on the soil bacterial community and is of benefit for the uptakes of carbon and nitrogen in Malus sieversii plants.

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Section: Discussionmentioning

confidence: 99%

Effects of Temperature and Nitrogen Application on Carbon and Nitrogen Accumulation and Bacterial Community Composition in Apple Rhizosphere Soil

Zhang

Phillip

et al. 2022

Front. Plant Sci.

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“…The authors proposed a method involving the application to the soil of a gel with an encrusted substrate, and the colouring in Bradford solution of the unreacted substrate stuck in the gel after the incubation period, resulting in a colour map that can be translated into a mapped numerical estimation of enzymatic activity through digital image analysis. A similar method of in situ zymography, based on fluorescent substrate and able to continuously monitor the changes of mapped spots of enzymatic activity, was proposed byLiu et al (2022) Levakov et al (2021). developed a soil zymography method involving a suction cup porous interface to analyse the activity of free soil enzymes passing through it with the soil pore water, along a soil column.…”

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confidence: 99%

Altered activities of extracellular soil enzymes by the interacting global environmental changes

Zuccarini

Sardans

Asensio

et al. 2023

Global Change Biology

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Soil enzymes are crucial in mediating ecosystems' responses to environmental drivers, so that the comprehension of their sensitivity to drivers of global change can help make predictions of future scenarios and design tailored interventions of biomanipulation. Drivers of global change usually act in combination of two or more, and indirect effects of one driver acting through modification of another one often occur, yet most of both manipulative and meta‐analysis studies available tend to focus on the direct effect of one single driver on the activity of specific soil enzymes. One of the biggest challenges is, therefore, represented by the difficulty in assessing the interactions between different drivers, due to the complexity of disentangling the single direct effects from the indirect and combined ones. In this review, after elucidating the general mechanisms of soil enzyme production and activity regulation, we display the state‐of‐the‐art knowledge on direct, indirect and combined effects of the main drivers of global change on soil enzyme activities, identify gaps in knowledge and challenges from research, plus we analyse how this can reverberate in the future of biomanipulation techniques for the improvement of ecosystem services. We conclude that qualitative but not quantitative outcomes can be predicted for some interactions such as warming + drought or warming + CO2, while for other ones, the results are controversial: future basic research will have to center on this holistic approach. A general trend toward the overall increase of soil enzyme activities and acceleration of biogeochemical cycles will persist, until an inflection will be caused by factors such as future shifts in microbial communities and changes in carbon use efficiency. Applied research will develop toward the refinement of “in situ” analytical systems for the study of soil enzyme activities and the support of bioengineering for the better tailoring of interventions of biomanipulation.

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“…Thus, the perchlorate treatment was mostly affected by the soil's physical properties. Following previous experience regarding perchlorate treatment (Levakov et al, 2021(Levakov et al, , 2019, it is reasonable to assume that higher perchlorate concentrations https://doi.org/10.5194/egusphere-2022-1179 Preprint. Discussion started: 23 November 2022 c Author(s) 2022.…”

Section: Perchlorate Biodegradation and Transport In The Deep Vadose ...mentioning

confidence: 99%

“…(> 1000 mg l -1 ) would undergo complete degradation. Degradation of less effective electron acceptors, such as sulphate reduction and methanogenesis, as observed in the reactive soil (Levakov et al, 2021(Levakov et al, , 2020, can indicate a higher potential for microbial activity. In this case, one would expect larger degradation coefficients than the fitted parameters presented in Table 340 3.…”

Section: Perchlorate Biodegradation and Transport In The Deep Vadose ...mentioning

confidence: 99%

“…Therefore, the thickness of the bioactive layer used for full degradation of perchlorate is currently less than 50 cm. Based on the various reduction processes (such as iron and sulphate reduction, and methanogenesis) occurring in the upper few meters of the soil (Avishai et al, 2017;Levakov et al, 365 2020Levakov et al, 365 , 2019 and the high general microbial activity found at these depths (Levakov et al, 2021), we assume that the biodegradation potential can be increased and the soil can be used as a natural bioreactor for high perchlorate concentrations (as high as 5000 mg l -1 ). After 550 days, when most of the perchlorate was flushed from the vadose zone to the groundwater, as shown in Figure 7, the concentration in the groundwater decreased accordingly.…”

Section: Perchlorate Mass Balance For the Groundwatermentioning

confidence: 99%

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Quantification of In-situ Remediation of Deep Unsaturated Zone and Groundwater

Levakov

Ronen

Turkeltaub

et al. 2022

Preprint

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Abstract. In-situ bioremediation techniques are cost-effective, environmentally friendly, and sustainable. This study examined a large-scale in-situ treatment of an unsaturated zone and a local groundwater system that were heavily contaminated with perchlorate and other co-contaminants, including nitrate, chlorate, and RDX. Principally, the upper section of the unsaturated zone was used as a bioreactor for treating the deep unsaturated zone and groundwater. The treatment was based on a cyclic process that included pumping contaminated groundwater, adding an essential electron donor, and injecting the amended water back into the top-soil, which was used as a bioreactor in the treatment process. In the shallow soil, the local bacteria reduced the perchlorate to chloride and water, and the treated water continued to displace the major pollutants from the deep part of the vadose zone, where the biological potential for contaminant degradation is low, towards the water table. The contaminated leachates were pumped back to the surface with polluted groundwater as part of the cyclic treatment process. Results show that the other co-contaminants, including nitrate, chlorate, and RDX, were removed. Water flow and reactive transport models were calibrated and validated against a time series of the water contents and bromide and perchlorate concentrations that were obtained across the unsaturated zone using the VMS. The calibrated models enabled quantifying the clean-up process and estimating the required time for full perchlorate removal. According to the model's predictions, after 700 days of continuous operation, all the perchlorate, in a total amount of 7754 kg, would be removed from the unsaturated zone. To obtain full removal, the modelling simulations suggest that the in-situ bioremediation should be implemented for an additional 200 days. Ultimately, we present a low-cost, efficient method for treating perchlorate contamination and potentially that of other pollutants in the subsurface.

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Continuous in-situ measurement of free extracellular enzyme activity as direct indicator for soil biological activity

Cited by 17 publications

References 73 publications

Effects of Temperature and Nitrogen Application on Carbon and Nitrogen Accumulation and Bacterial Community Composition in Apple Rhizosphere Soil

Effects of Temperature and Nitrogen Application on Carbon and Nitrogen Accumulation and Bacterial Community Composition in Apple Rhizosphere Soil

Altered activities of extracellular soil enzymes by the interacting global environmental changes

Quantification of In-situ Remediation of Deep Unsaturated Zone and Groundwater

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