scholarly journals Estimation of baseline levels of bacterial community tolerance to Cr, Ni, Pb, and Zn in unpolluted soils, a background for PICT (pollution-induced community tolerance) determination

2021 ◽  
Author(s):  
Claudia Campillo-Cora ◽  
Diego Soto-Gómez ◽  
Manuel Arias-Estévez ◽  
Erland Bååth ◽  
David Fernández-Calviño
Keyword(s):  
Heavy Metals ◽  
Bacterial Community ◽  
Clay Content ◽  
Parent Material ◽  
Leucine Incorporation ◽  
Organic C ◽  
Soil Microbial ◽  
Microbial Response ◽  
Baseline Levels ◽  
Community Tolerance

AbstractThe PICT method (pollution-induced community tolerance) can be used to assess whether changes in soil microbial response are due to heavy metal toxicity or not. Microbial community tolerance baseline levels can, however, also change due to variations in soil physicochemical properties. Thirty soil samples (0–20 cm), with geochemical baseline concentrations (GBCs) of heavy metals and from five different parent materials (granite, limestone, schist, amphibolite, and serpentine), were used to estimate baseline levels of bacterial community tolerance to Cr, Ni, Pb, and Zn using the leucine incorporation method. General equations (n = 30) were determined by multiple linear regression using general soil properties and parent material as binary variables, explaining 38% of the variance in log IC50 (concentration that inhibits 50% of bacterial growth) values for Zn, with 36% for Pb, 44% for Cr, and 68% for Ni. The use of individual equations for each parent material increased the explained variance for all heavy metals, but the presence of a low number of samples (n = 6) lead to low robustness. Generally, clay content and dissolved organic C (DOC) were the main variables explaining bacterial community tolerance for the tested heavy metals. Our results suggest that these equations may permit applying the PICT method with Zn and Pb when there are no reference soils, while more data are needed before using this concept for Ni and Cr.

scholarly journals Effect of Metal-Rich Sludge Amendments on the Soil Microbial Community

1998 ◽  
Vol 64 (1) ◽  
pp. 238-245 ◽  
Author(s):  
Erland Bååth ◽  
Montserrat Díaz-Raviña ◽  
Åsa Frostegård ◽  
Colin D. Campbell
Keyword(s):  
Microbial Community ◽  
Bacterial Community ◽  
Soil Microbial Community ◽  
Agricultural Soils ◽  
Phospholipid Fatty Acid ◽  
Community Based ◽  
Soil Microbial ◽  
Biolog System ◽  
Community Tolerance ◽  
Dose Response Effect

ABSTRACT The effects of heavy-metal-containing sewage sludge on the soil microbial community were studied in two agricultural soils of different textures, which had been contaminated separately with three predominantly single metals (Cu, Zn, and Ni) at two different levels more than 20 years ago. We compared three community-based microbiological measurements, namely, phospholipid fatty acid (PLFA) analysis to reveal changes in species composition, the Biolog system to indicate metabolic fingerprints of microbial communities, and the thymidine incorporation technique to measure bacterial community tolerance. In the Luddington soil, bacterial community tolerance increased in all metal treatments compared to an unpolluted-sludge-treated control soil. Community tolerance to specific metals increased the most when the same metal was added to the soil; for example, tolerance to Cu increased most in Cu-polluted treatments. A dose-response effect was also evident. There were also indications of cotolerance to metals whose concentration had not been elevated by the sludge treatment. The PLFA pattern changed in all metal treatments, but the interpretation was complicated by the soil moisture content, which also affected the results. The Biolog measurements indicated similar effects of metals and moisture to the PLFA measurements, but due to high variation between replicates, no significant differences compared to the uncontaminated control were found. In the Lee Valley soil, significant increases in community tolerance were found for the high levels of Cu and Zn, while the PLFA pattern was significantly altered for the soils with high levels of Cu, Ni, and Zn. No effects on the Biolog measurements were found in this soil.

scholarly journals Parent material and organic matter control soil microbial processes in African tropical rainforests 

2021 ◽  
Author(s):  
Laurent Kidinda Kidinda ◽  
Folasade Kemi Ologoke ◽  
Cordula Vogel ◽  
Karsten Kalbitz ◽  
Sebastian Doetterl
Keyword(s):  
Microbial Biomass ◽  
Tropical Rainforest ◽  
Parent Material ◽  
Microbial Processes ◽  
Tropical Rainforests ◽  
Microbial Biomass C ◽  
Organic C ◽  
Soil Microbial ◽  
Microbial C ◽  
C Limitation

<p>Microbial processes are one of the key factors driving carbon (C) and nutrient cycling in terrestrial ecosystems, and are strongly controlled by the equilibrium between resource availability and demand. In deeply weathered tropical rainforest soils of Africa, it remains unclear whether patterns of microbial processes differ between soils developed from geochemically contrasting parent material. Here, we investigate patterns of soil microbial processes and their controls in tropical rainforests of Africa. We used soil developed from three geochemically distinct parent material (mafic, felsic, mixed sedimentary rocks) and three soil depths (0−70 cm). We measured microbial biomass C and enzyme activity at the beginning and end of a 120-day incubation experiment. We also conducted a vector analysis based on ecoenzymatic stoichiometry to assess microbial C and nutrient limitations. We found that microbial C limitation was highest in the mixed sedimentary region and lowest in the felsic region, which we propose was related to the strength of contrasting C stabilization mechanisms and varying C quality. None of the investigated regions and soil depths showed signs of nitrogen (N) limitation for microbial processes. Microbial phosphorus (P) limitation increased with soil depth, indicating that subsoils in the investigated soils were depleted in rock-derived nutrients and are therefore dependent on efficient nutrient recycling. Microbial C limitation was lowest in subsoils, indicating that subsoil microbes cannot significantly participate in C cycling and limit C storage if oxygen is not available, but can do so in our laboratory incubation experiment under well aerated conditions. Using multivariable regressions, we demonstrate that microbial biomass C normalized to soil organic C content (MBC<sub>SOC</sub>) is controlled by soil geochemistry and substrate quality, while microbial biomass C normalized to soil weight (MBC<sub>Soil</sub>) is predominantly driven by resource distribution (i.e., depth distribution of organic C). We conclude that due to differences in resource availability, microbial processes in deeply weathered tropical rainforest soils greatly vary across geochemical regions.</p>

scholarly journals Total and bioavailable heavy metals in the soils of two adjacent forests

2022 ◽  
Keyword(s):  
Heavy Metals ◽  
Principal Component Analysis ◽  
Total Concentration ◽  
Principal Component ◽  
Parent Material ◽  
Litter Layer ◽  
Pca Analysis ◽  
Organic C ◽  
Acid Forest Soils ◽  
Total Concentrations

<p>The concentrations and comparisons of total and available metals Cd, Cr, Ni, Pb and the metalloid As were examined in two adjacent acid forest soils in Greece under oak and beech together with the dependency of their availability. It was found that the soil in the beech plot had higher concentrations of total elements with the exception of the litter layer (L) where most metals did not differ. It is probable that the parent material of the beech soil contained some metamorphic mafic material. The surface soils for both stands were moderately enriched with Pb, Cd and As, whereas for Cr and Ni the enrichment was minimal. The concentrations of available elements (extracted with DTPA) were higher in the beech soil. The availability of most metals was affected by the pH, the organic C, the ratio of C/N and the total concentration of the metals. Through a Principal Component Analysis (PCA) analysis, it was found that 63-75% of the concentrations variance of the available metals was explained. The percentages of available metals with regard to their total concentrations in soils were higher in the beech plot in the FH layer but in the mineral layers, they did not differ apart from Pb. The concentrations of the metals in the leaves of both species in three consecutive years did not differ with the exception of Cd, the concentration of which was higher in the beech leaves.</p>

scholarly journals Soil CO2 respiration: Comparison of chemical titration, CO2 IRGA analysis and the Solvita gel system

2008 ◽  
Vol 23 (2) ◽  
pp. 171-176 ◽  
Author(s):  
R.L. Haney ◽  
W.F. Brinton ◽  
E. Evans
Keyword(s):  
Regression Analysis ◽  
Microbial Activity ◽  
Clay Content ◽  
Soil Microbial Activity ◽  
Gas Analysis ◽  
Soil Samples ◽  
Organic C ◽  
Soil Microbial ◽  
Highly Correlated ◽  
Gel System

AbstractThe measurement of soil carbon dioxide respiration is a means to gauge biological soil fertility. Test methods for respiration employed in the laboratory vary somewhat, and to date the equipment and labor required have somewhat limited more widespread adoption of such methodologies. The purpose of this research is to compare the results of measured soil CO2 respiration using three methods: (1) titration method; (2) infrared gas analysis (IRGA); and (3) the Solvita gel system for soil CO2 analysis. We acquired 36 soil samples from across the USA for comparison, which ranged in pH from 4.5 to 8.5, organic C from 0.8 to 4.6% and the clay content from 6 to 62%. All three methods were highly correlated with each other after 24-h of incubation (titration and Solvita r2=0.82, respirometer and Solvita r2=0.79 and titration versus respirometer r2=0.95). The 24-h (1-day) CO2 release from all three methods was also highly correlated to both basal soil respiration (7–28 days) and cumulative 28-day CO2 respiration. An additional 24 soil samples were acquired and added to the original 36, for a total of 60 soil samples. These samples were used for calibration of the Solvita gel digital color reader results using CO2-titration results and regression analysis. Regression analysis resulted in the equation y=20.6∗(Solvita number)−16.5 with an r2 of 0.83. The data suggest that the Solvita gel system for soil CO2 analysis could be a simple and easily used method to quantify soil microbial activity. Applications may also exist for the gel system for in situ measurements in surface gas chambers. Once standardized soil sampling and laboratory analysis protocols are established, the Solvita method could be easily adapted to commercial soil testing labs as an index of soil microbial activity.

scholarly journals Tolerance of soil bacterial community to tetracycline antibiotics induced by As, Cd, Zn, Cu, Ni, Cr and Pb pollution

2021 ◽  
Author(s):  
Vanesa Santás-Miguel ◽  
Avelino Núñez-Delgado ◽  
Esperanza Álvarez-Rodríguez ◽  
Montserrat Díaz-Raviña ◽  
Manuel Arias-Estévez ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Bacterial Community ◽  
Bacterial Communities ◽  
Soil Samples ◽  
Leucine Incorporation ◽  
Human Pathogens ◽  
High Concentration ◽  
Tetracycline Antibiotics ◽  
Co Tolerance

Abstract. The widespread use of both heavy metals and antibiotics in livestock farming and their subsequent arrival on agricultural soils through manure/slurry spreading has become a problem of vital importance for human health and the environment. In the current research, a laboratory experiment was carried out for 42 days to study co-selection for tolerance of three tetracycline antibiotics (tetracycline, TC; oxytetracycline, OTC; chlortetracycline, CTC) in soils polluted with heavy metals (As, Cd, Zn, Cu, Ni, Cr and Pb) at high concentration levels (1000 mg kg−1 of each one, separately). Pollution Induced Community Tolerance (PICT) of the bacterial community was estimated using the leucine incorporation technique. The Log IC50 (logarithm of the concentration causing 50 % inhibition in bacterial community growth) values obtained in uncontaminated soil samples for all the heavy metals tested showed the following toxicity sequence: Cu > As > Cr ≥ Pb ≥ Cd > Zn > Ni. However, in polluted soil samples the toxicity sequence was: Cu > Pb ≥ As ≥ Cd ≥ Cr ≥ Ni ≥ Zn. Moreover, at high metal concentrations the bacterial communities show tolerance to the metal itself, this taking place for all the metals tested in the long term. The bacterial communities of the soil polluted with heavy metals showed also long-term co-tolerance to TC, OTC, and CTC. This kind of studies, focusing on the eventual increases of tolerance and co-tolerance of bacterial communities in agricultural soil, favored by the presence of other pollutants, is of crucial importance, mostly bearing in mind that the appearance of antibiotic resistance genes in soil bacteria could be transmitted to human pathogens.

Soil microbial response to silicate fertilization reduces bioavailable arsenic in contaminated paddies

2021 ◽  
pp. 108307
Author(s):  
Suvendu Das ◽  
Hyun Young Hwang ◽  
Hyeon Ji Song ◽  
Song Rae Cho ◽  
Joy D. Van Nostrand ◽  
...  
Keyword(s):  
Soil Microbial ◽  
Microbial Response
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