Community level physiological profiles of microbial communities from forest humus polluted with different amounts of Zn, Pb, and Cd—Preliminary study with BIOLOG ecoplates (original) (raw)
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Characterization of the forest humus microbial community in a heavy metal polluted area
Soil Biology and Biochemistry, 2005
Various parameters of the soil microbial community may be used in soil quality evaluation and environmental risk assessment. The objectives of this study were to assess the effects of different environmental factors on the characteristics of forest humus microbial communities, and to test which environmental factors most affect the gross microbial indices and physiological profiles of these communities. Samples were taken at 71 plots located in a heavily polluted area of the Krakowsko-Częstochowska upland in southern Poland. The samples were analyzed for pH in KCl (pH KCl ), organic C (C org ), total N (N t ) and S (S t ), and for total and soluble Zn, Pb and Cd concentrations. The considered microbial parameters included basal respiration (BAS), microbial biomass (C mic ), C mic -to-C org ratio, and community-level physiological profiles (CLPPs) studied using BIOLOG w Ecoplates. Multiple regression analysis was used to estimate the effects of humus properties on the microbial parameters. It indicated that S t and C org -to-N t ratio were the most important factors positively affecting C mic (bZ0.15 and 0.11, respectively) and BAS (bZ0.13 and 0.08, respectively). The C mic -to-C org ratio was related positively to S t (bZ0.12) but negatively to N t (bZK0.08). The effects of pH KCl and heavy metals on the gross microbial indices were significant but less important. The most important effect on microbial activity on BIOLOG w plates and CLPPs was from pH KCl . The other significant variables included S t , C org -to-N t and interactions of heavy metals with pH KCl . It was concluded that C mic , C mic -to-C org and BAS might be good indicators of the general status of soil microbial communities, but their use in studying heavy metal effects may entail difficulties in separating the effects of other factors. The sensitivity of the BIOLOG w test to pH KCl suggests that it may be useful for studying the effects of acidification or liming on soil microbial communities. The significant effect of the interactions between heavy metals and other variables on physiological profiles indicated that high heavy metal content affects the metabolic functions of soil microbial populations. q
Effects of Cd and Pb on soil microbial community structure and activities
Envtl. Sci. Poll. Research, 2010
Background, aim, and scope Soil contamination with heavy metals occurs as a result of both anthropogenic and natural activities. Heavy metals could have long-term hazardous impacts on the health of soil ecosystems and adverse influences on soil biological processes. Soil enzymatic activities are recognized as sensors towards any natural and anthropogenic disturbance occurring in the soil ecosystem. Similarly, microbial biomass carbon (MBC) is also considered as one of the important soil biological activities frequently influenced by heavy metal contamination. The polymerase chain reaction-denaturing gradient gel electrophoresis (DGGE) has recently been used to investigate changes in soil microbial community composition in response to environmental stresses. Soil microbial community structure and activities are difficult to elucidate using single monitoring approach; therefore, for a better insight and complete depiction of the soil microbial situation, different approaches need to be used. This study was conducted in a greenhouse for a period of 12 weeks to evaluate the changes in indigenous microbial community structure and activities in the soil amended with different application rates of Cd, Pb, and Cd/Pb mix. In a field environment, soil is contaminated with single or mixed heavy metals; so that, in this research, we used the selected metals in both single and mixed forms at different application rates and investigated their toxic effects on microbial community structure and activities, using soil enzyme assays, plate counting, and advanced molecular DGGE technique. Soil microbial activities, including acid phosphatase (ACP), urease (URE), and MBC, and microbial community structure were studied. Materials and methods A soil sample (0-20 cm) with an unknown history of heavy metal contamination was collected and amended with Cd, Pb, and Cd/Pb mix using the CdSO 4 and Pb(NO 3 ) 2 solutions at different application rates. The amended soils were incubated in the greenhouse at 25±4°C and 60% water-holding capacity for 12 weeks. During the incubation period, samples were collected from each pot at 0, 2, 9, and 12 weeks for enzyme assays, MBC, numeration of microbes, and DNA extraction. Fumigationextraction method was used to measure the MBC, while plate counting techniques were used to numerate viable heterotrophic bacteria, fungi, and actinomycetes. Soil DNAs were extracted from the samples and used for DGGE analysis. Results ACP, URE, and MBC activities of microbial community were significantly lower (p <0.05) in the metal-amended samples than those in the control. The enzyme inhibition extent was obvious between different incubation periods and varied as the incubation proceeded, and the highest rate was detected in the samples after 2 weeks. However, the lowest values of ACP and URE activities (35.6% and 36.6% of the control, respectively) were found in the Cd 3 /Pb 3 -treated sample after 2 weeks. Similarly, MBC was strongly decreased in both Cd/Pbamended samples and highest reduction (52.4%) was Environ Sci Pollut Res (
Effects of Cd, Zn, or both on soil microbial biomass and activity in a clay loam soil
2007
We investigated Cd, Zn, and Cd+Zn toxicity to soil microbial biomass and activity, and indigenous Rhizobium leguminosarum biovar trifolii, in two near neutral pH clay loam soils, under long-term arable and grassland management, in a 6-month laboratory incubation, with a view to determining the causative metal. Both soils were amended with Cd-or Zn-enriched sewage sludge, to produce soils with total Cd concentrations at four times (12 mg Cd g −1 soil), and total Zn concentrations (300 mg Zn kg −1 soil) at the EU upper permitted limit. The additive effects of Cd plus Zn at these soil concentrations were also investigated. There were no significant differences in microbial biomass C (B C ), biomass ninhydrin N (B N ), ATP, or microbial respiration between the different treatments. Microbial metabolic quotient (defined as qCO 2 =units of CO 2 -C evolved unit −1 biomass C unit −1 time) also did not differ significantly between treatments. However, the microbial maintenance energy (in this study defined as qCO 2 -to-μ ratio value, where μ is the growth rate) indicated that more energy was required for microbial synthesis in metal-rich sludgetreated soils (especially Zn) than in control sludge-treated soils. Indigenous R.leguminosarum bv. trifolii numbers were not significantly different between untreated and sludgetreated grassland soils after 24 weeks regardless of metal or metal concentrations. However, rhizobial numbers in the arable soils treated with metal-contaminated sludges decreased significantly (P<0.05) compared to the untreated control and uncontaminated sludge-treated soils after 24 weeks. The order of decreasing toxicity to rhizobia in the arable soils was Zn>Cd>Cd+Zn.
Microbial biomass and ATP in smelter-polluted forest humus
Bulletin of Environmental Contamination and Toxicology, 1991
Many aspects of microbial activity in soil have been studied in connection with heavy metal pollution (Babich and Stotzky 1985; Duxbury 1985; Doelman 1986; B~t~ith 1989), but few investigations have included microbial biomass. Brookes and McGrath (1984) and Brookes et al. (1986), however, showed that amendments with heavy-metal rich sewage sludge to agricultural soils decreased microbial biomass as measured by the fumigation-incubation method. A decrease in ATP content of the soil was also found, but the biomass-C/ATP ratio was unaffected by the soil concentration of heavy metals. Soil heavy metal content, however, was only increased to 3-5 times the background values.
Bacterial community structure and activity in different Cd-treated forest soils
FEMS Microbiology Ecology, 2000
In this study we compared indicators of Cd bioavailability (water extracts, Lakanen extracts, free ions) and ecotoxicity in forest soils with contrasting physico-chemical characteristics. Soil samples were treated with CdCl 2 solutions (0, 0.1, 1, 10 and 100 mM) and incubated for 30 days. Microbial activity indexes (acid phosphatase, b-glucosidase, basal respiration) and changes in bacterial community structure using terminal restriction fragment length polymorphism (T-RFLP) fingerprinting were investigated. The Cd concentrations measured ranged from 1% to 37% of the total additions in water extracts, to higher levels in Lakanen extracts. Effects of Cd were observed at bioavailable concentrations exceeding United Nations/European Economic Commission UN/ECE guidelines for total Cd in the soil solution. Basal respiration was the most affected index, while enzymatic activities showed variable responses to the Cd treatments. We also noticed that soils with pH higher than 6.7 and clay content higher than 50% showed inhibition of basal respiration but no marked shift in bacterial community structure. Soils with lower pH (pH o5.8) with less clay content (o 50%) showed in addition strong changes in the bacterial community structure. Our results provide evidence for the importance of relating the effects of Cd on the soil communities to soil properties and to bioavailability.
Water, Air, & Soil Pollution, 2016
The objective of this study was to assess the impact of metal contamination on microbial functional diversity and enzyme activity in forest soils. This study involved the evaluation of the influence of the texture, carbon content and distance to the source of contamination on the change in soil microbial activity, which did not investigate in previous studies. The study area is located in southern Poland near the city of Olkusz around the flotation sedimentation pond of lead and zinc at the Mining and Metallurgical Company BZGH Bolesław, Inc.^. The central point of the study area was selected as the middle part of the sedimentation pond. The experiment was conducted over a regular 500 × 500-m grid, where 33 sampling points were established. Contents of organic carbon and trace elements (Zn, Pb and Cd), pH and soil texture were investigated. The study included the determination of dehydrogenase and urease activities and microbial functional diversity evaluation based on the community-level physiological profiling approach by Biolog EcoPlate. The greatest reduction in the dehydrogenase and urease activities was observed in light sandy soils with Zn content >220 mg • kg −1 and a Pb content > 100 mg • kg −1. Soils with a higher concentration of fine fraction, despite having the greatest concentrations of metals, were characterized by high rates of Biolog®-derived parameters and a lower reduction of enzyme activity.
FEMS Microbiology Ecology, 2000
The separate and combined effects of moderate levels of acid load and Cu-Ni deposition on humus (F/H layer) microbial community structure were examined six growing seasons after the start of an artificial irrigation experiment. A 2 P -factorial design with acid load (pH 3.1) and Cu-Ni addition was used. The acid application resulted in acidification as defined by humus chemistry, including a decrease in the concentration of base cations and an increase in the concentration of H , Al and Fe, leading to a decrease in humus pH from 4.10 to 3.95. The metal additions resulted in a 2^3-fold increase in humus total Cu and Ni concentrations. The treatments did not affect the total microbial biomass, measured by substrate-induced respiration, or the basal respiration rate. However, the microbial community structure determined by phospholipid fatty acid (PLFA) analysis showed that the acid load affected the bacterial part of the community. The relative amount of branched PLFAs common to Gram-positive bacteria increased with decreasing humus pH, and the bacterial community was also adapted to more acidic conditions. The metal addition alone did not cause clear changes in the microbial community structure or bacterial tolerance to Cu or Ni. The combined acid and metal treatment induced similar changes in the microbial community structure as the acid treatment alone. z