| 1. |
- Aldén, Louise, et al.
(författare)
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Effects of sulfamethoxazole on soil microbial communities after adding substrate
- 2009
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Ingår i: Soil Biology & Biochemistry. - : Elsevier BV. - 0038-0717. ; 41:4, s. 840-848
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Tidskriftsartikel (refereegranskat)abstract
- The effect of the antibiotic sulfamethoxazole (SMX) on soil bacteria was studied using two methods (leucine incorporation and Biolog plates) of estimating pollution-induced community tolerance (PICT). SMX was added to an agricultural soil in a microcosm setup. The addition of different substrates (manure and alfalfa), and a non-amended soil, were also studied over 5 weeks. PICT measurements were validated by comparison with other measurements. Community structure was assessed using phospholipid fatty acid (PLFA) analysis and community-level physiological profiling (CLPP), and bacterial growth was estimated using leucine incorporation. Increased PICT was found at SMX concentrations of 20 and 500 mg SMX kg(-1) soil in samples containing manure and alfalfa, and at 500 mg SMX kg(-1) soil in non-amended soil (only concentration tested) using leucine incorporation. No effect was seen at 1 mg SMX kg(-1) soil. It was not necessary to add any substrate to increase the microbial activity in order to detect the effects of a bacteriostatic toxicant such as SMX when using measures based on bacterial growth. Direct inhibition of bacterial growth 2 days after SMX addition was correlated to PICT. No major changes in PICT due to SMX addition were found when using Biolog plates. However, there was a tendency towards increased PICT at the higher SMX concentrations in the manure-amended soil. Thus, different methods of detecting PICT have different sensitivities in detecting the toxic effects of SMX The effects of substrate amendment were reflected by changes in the microbial community, estimated using both PLEA and CLPP SMX was found to have a clear effect at the two highest levels of SMX in the manure- and alfalfa-amended soils, with an increase in fungal and a decrease in bacterial PLFAs. Little difference in the PLFA composition was found in the non-amended soil. CLPP was only affected at the highest SMX concentration. Although different variables showed different sensitivities to the effects of SMX, the results were consistent with an initial decrease in bacterial growth rates of sensitive species, which eventually transformed into more tolerant species, altering the community composition. (C) 2009 Elsevier Ltd. All rights reserved.
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| 2. |
- Aldén, Louise, et al.
(författare)
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No long-term persistence of bacterial pollution-induced community tolerance in tylosin-polluted soil
- 2008
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 1520-5851 .- 0013-936X. ; 42:18, s. 6917-6921
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Tidskriftsartikel (refereegranskat)abstract
- Pollution-induced community tolerance (PICT) of soil bacteria to the antibiotic tylosin was studied over 95 days. Tylosin was added at increasing concentrations, together with different amounts of alfalfa to study the effects of substrate addition on PICT and bacterial growth in soil. The leucine incorporation technique was used to estimate bacterial growth and as a detection method in the PICT concept. Direct inhibition of the bacterial growth rates, resulting in a dose-response curve, was found above 50 mg of tylosin kg(-1) of soil two days after tylosin addition (IC50 value of 960 mg tylosin kg(-1)). After 10 days of exposure to at least 50 mg of tylosin kg(-1), the PICT was observed and correlated to inhibition of bacterial growth by tylosin. A return of the PICT to control levels was found over time, and after 95 days at 1500 mg of tylosin kg(-1), essentially no PICT was found, as compared to the unpolluted control soil. The return of PICT to pre-exposure levels was not totally reflected in the recovery of bacterial growth. Alfalfa addition did not affect the inhibitory effect of tylosin on bacterial growth rates; neither did it alter the PICT. Since tylosin is relatively rapidly degraded in soil, our results indicate that the PICT will return to prepollution levels when the selective pressure of the toxicant is removed and will thus be a useful technique for monitoring remediation measures.
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| 3. |
- Aldén, Louise
(författare)
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Pollution-Induced Community Tolerance (PICT) of Bacteria: Evaluation in Phenol- and Antibiotic Polluted Soil
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The effects of organic pollutants on the soil microbial community were studied in this work. The main aim was to evaluate the use of pollution-induced community tolerance (PICT) in studying the effects of pollution. The leucine incorporation technique (indicating bacterial growth) was used to monitor changes in tolerance. The impact of toxic substances on bacterial and fungal growth (acetate-in-ergosterol incorporation) and microbial community structure (PLFA) was also studied. Increased PICT was found at increasing concentrations of both phenols and antibiotics (tylosin and sulfamethoxazole, SMX) in soil. However, at higher concentrations of phenol and tylosin no further increase in PICT was observed. The extent of PICT varied depending on the toxicant. Re-development of PICT was found in tylosin-polluted soil, indicating that PICT can be used to monitor soil remediation. The specificity of PICT was studied by examining co-tolerance to other phenols (2-chlorophenol, 2,4-dichlorophenol and 2,3,6-trichlorophenol) and metals (Cu and Zn) in phenol-polluted soil. Co-tolerance to other phenols was observed, however, always to a lower extent than to phenol. No co-tolerance to metals was seen. Direct inhibiting effects on bacterial growth were correlated to PICT. In phenol-polluted soil bacterial growth recovered over time and growth rates at high phenol concentrations were higher than in the unpolluted controls. In tylosin-polluted soil bacterial growth rates recovered to those in the unpolluted soil, while in SMX-polluted soil bacterial growth recovered only slightly over time. PICT to phenol and SMX was reflected in structural changes of the soil microbial community. In SMX-polluted soil a decrease in bacterial PLFAs was found, together with a corresponding increase in fungal PLFAs. A dramatic decrease in bacterial growth and increase in fungal growth were also observed after adding different bacterial antibiotics to soil, indicating competition between fungi and bacteria in soil. The leucine incorporation technique was shown to be a fast and sensitive method of estimating PICT and the direct inhibition of soil bacteria exposed to organic pollutants. The PICT concept was found to be a valuable tool in determining the toxic effects of organic pollutants and in distinguishing the toxic effects from other environmental factors. However, co-tolerance between different toxicants can complicate the interpretation of PICT.
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| 4. |
- Aldén, Louise, et al.
(författare)
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Rapid method of determining factors limiting bacterial growth in soil
- 2001
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Ingår i: Applied and Environmental Microbiology. - 0099-2240. ; 67:4, s. 1830-1838
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Tidskriftsartikel (refereegranskat)abstract
- A technique to determine which nutrients limit bacterial growth in soil was developed. The method was based on measuring the thymidine incorporation rate of bacteria after the addition of C, N, and P in different combinations to soil samples. First, the thymidine incorporation method was tested in two different soils: an agricultural soil and a forest humus soil. Carbon (as glucose) was found to be the limiting substance for bacterial growth in both of these soils. The effect of adding different amounts of nutrients was studied, and tests were performed to determine whether the additions affected the soil pH and subsequent bacterial activity. The incubation time required to detect bacterial growth after adding substrate to the soil was also evaluated. Second, the method was used in experiments in which three different size fractions of straw (1 to 2, 0.25 to 1, and <0.25 mm) were mixed into the agricultural soil in order to induce N limitation for bacterial growth. When the straw fraction was small enough (<0.25 mm), N became the limiting nutrient for bacterial growth after about 3 weeks. After the addition of the larger straw fractions (1 to 2 and 0.25 to 1 mm), the soil bacteria were C limited throughout the incubation period (10 weeks), although an increase in the thymidine incorporation rate after the addition of C and N together compared with adding them separately was seen in the sample containing the size fraction from 0.25 to 1 mm. Third, soils from high-pH, limestone-rich areas were examined. P limitation was observed in one of these soils, while tendencies toward P limitation were seen in some of the other soils.
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| 5. |
- Aldén, Louise, et al.
(författare)
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The use of leucine incorporation to determine the toxicity of phenols to bacterial communities extracted from soil
- 2008
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393. ; 38:1, s. 34-41
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Tidskriftsartikel (refereegranskat)abstract
- The toxicity of different phenols to the soil bacterial community was studied in the laboratory using the leucine incorporation technique. The effects of environmental factors such as pH, temperature and binding strength to soil particles were also assessed in order to deduce confounding effects due to the chemical and physical conditions in the soil from which the bacterial community was extracted. Bacterial growth varied with temperature and pH, the optima being at around 33 degrees C and pH 7 in a soil with a natural pH of 7. The toxicity of different phenols varied less than bacterial growth as a function of temperature and pH, but the toxicity of 2,3,6-trichlorophenol increased at lower temperatures and pH. The pH affected the toxicity in the same way in soils with naturally different pH values and when the pH was changed using buffers, showing that this was a direct effect of pH and was not due to different communities in different soils. The degree to which the bacteria were bound to soil particles had no effect on the toxicity of phenols. Neither did freezing nor thawing the soil have any effect on toxicity, although the bacterial growth was lower in frozen soil than in non-frozen soil. Increasing numbers of substitutes on the phenols increased their toxicity to soil bacteria, and chlorine substitutes were more toxic than the corresponding methyl substitutes. The toxicity of the phenols studied to the whole soil bacterial community was correlated with literature data on the toxicity to the single species Pseudomonas putida. Applying the leucine incorporation technique to the bacterial community extracted from soil was shown to be a rapid and sensitive method of estimating toxicity. The methodology also allowed differentiation between the effects of environmental factors on toxicity to the soil bacterial community and changes in the tolerance of the community. Thus, the development of pollution-induced community tolerance in phenol- and 2-chlorophenol-polluted soils could be shown. (c) 2007 Elsevier B.V. All rights reserved.
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| 6. |
- Aldén, Louise, et al.
(författare)
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Use of pollution-induced community tolerance of the bacterial community to detect phenol toxicity in soil.
- 2008
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Ingår i: Environmental Toxicology and Chemistry. - 0730-7268. ; 27:2, s. 334-340
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Tidskriftsartikel (refereegranskat)abstract
- Pollution-induced community tolerance (PICT) was used to study effects of phenol on soil bacteria. Phenol was added to an agricultural soil in a microcosm experiment. The effects were studied for up to four months. Bacterial growth rates were estimated with the leucine incorporation technique. This technique was also used as detection method for PICT. Changes in community structure were studied using the phospholipid fatty acid (PLFA) pattern. Increased phenol PICT of the bacterial community was found at phenol concentrations above 1 micromol/g wet weight soil. Direct inhibiting effect on bacterial growth rates 1 d after adding phenol was correlated to PICT. Phenol toxicity was reflected by changes in the structure of the bacterial community, although PICT appeared more sensitive than the PLFA method. In soil amended with 1 to 10 micromol phenol/g soil, bacterial growth recovered within one week. In the soil amended with the highest phenol concentration (30 micromol/g soil), bacterial growth rate recovered from total inhibition after 27 d, eventually reaching values six times higher than in the control. However, PICT did not change during the four months the experiment was performed. The specificity of PICT was also studied by examining cotolerance to 2-chlorophenol, 2,4-dichlorophenol, 2,3,6-trichlorophenol, Cu, and Zn. Adding phenol induced cotolerance of the bacterial community to the other phenols, although always at a lover level than to phenol. No cotolerance was found to metals in phenol-polluted soil. We conclude that the PICT concept is a valuable tool in determining phenol toxicity to bacterial communities, especially in situations where bacterial growth has recovered. Cotolerance between different phenols can, however, make interpretations of PICT more complicated.
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| 7. |
- Anderbrant, Olle, et al.
(författare)
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Occurrence of Z- and E-strain Ostrinia nubilalis in Sweden shortly after first detection of the Z-strain
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Ingår i: Journal of Applied Entomology. - 0931-2048.
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The European corn borer (ECB), Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), is a major pest insect in maize. New cultivars and climate change have allowed range expansion of the crop northwards in Europe, and a similar range expansion of associated pests has been predicted. ECB exists as two distinct pheromone strains using different blends of (E)-11-tetradecenyl acetate and (Z)-11-tetradecenyl acetate for sexual communication; in addition, the Z-strain feeds almost exclusively on maize. In Sweden, the maize cropping area has increased tenfold during the last two decades, increasing the potential for spread of the Z-strain, which was recorded for the first time in the country in 2010. Aim of the study/methods: In this study, we performed trapping experiments with strain-specific lures in maize fields in southern Sweden during 2013–2022 to monitor the presence and relative abundance of the two ECB strains and evaluate the potential increase of the Z-strain. Trapping was also performed at least 5 km away from maize fields. Molecular markers were used to verify the strain identity of trapped males and larvae that fed on maize. Results: Catch data revealed that both pheromone strains were present in the major maize cultivation areas of Sweden, as predicted by recent modelling studies. Our data indicate that the flight period of ECB in southern Sweden lasts from the middle of June to late August, with peak flight in July. Catches of both strains were low at all trapping sites and throughout the study period and decreased further during the years following the dry summer of 2018. No Z-strain males were trapped far away from maize fields. Conclusion: Based on our results, and the low levels of ECB-related damage observed in local maize fields, the Z-strain is currently not imposing a threat to Swedish maize growers.
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| 8. |
- Lee, Eun-Young, et al.
(författare)
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Play, Learn, and Teach Outdoors—Network (PLaTO-Net) : terminology, taxonomy, and ontology
- 2022
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Ingår i: International Journal of Behavioral Nutrition and Physical Activity. - : BioMed Central (BMC). - 1479-5868. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: A recent dialogue in the field of play, learn, and teach outdoors (referred to as “PLaTO” hereafter) demonstrated the need for developing harmonized and consensus-based terminology, taxonomy, and ontology for PLaTO. This is important as the field evolves and diversifies in its approaches, contents, and contexts over time and in different countries, cultures, and settings. Within this paper, we report the systematic and iterative processes undertaken to achieve this objective, which has built on the creation of the global PLaTO-Network (PLaTO-Net). Methods: This project comprised of four major methodological phases. First, a systematic scoping review was conducted to identify common terms and definitions used pertaining to PLaTO. Second, based on the results of the scoping review, a draft set of key terms, taxonomy, and ontology were developed, and shared with PLaTO members, who provided feedback via four rounds of consultation. Third, PLaTO terminology, taxonomy, and ontology were then finalized based on the feedback received from 50 international PLaTO member participants who responded to ≥ 3 rounds of the consultation survey and dialogue. Finally, efforts to share and disseminate project outcomes were made through different online platforms. Results: This paper presents the final definitions and taxonomy of 31 PLaTO terms along with the PLaTO-Net ontology model. The model incorporates other relevant concepts in recognition that all the aspects of the model are interrelated and interconnected. The final terminology, taxonomy, and ontology are intended to be applicable to, and relevant for, all people encompassing various identities (e.g., age, gender, culture, ethnicity, ability). Conclusions: This project contributes to advancing PLaTO-based research and facilitating intersectoral and interdisciplinary collaboration, with the long-term goal of fostering and strengthening PLaTO’s synergistic linkages with healthy living, environmental stewardship, climate action, and planetary health agendas. Notably, PLaTO terminology, taxonomy and ontology will continue to evolve, and PLaTO-Net is committed to advancing and periodically updating harmonized knowledge and understanding in the vast and interrelated areas of PLaTO.
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| 9. |
- Rousk, Johannes, et al.
(författare)
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Contrasting Short-Term Antibiotic Effects on Respiration and Bacterial Growth Compromises the Validity of the Selective Respiratory Inhibition Technique to Distinguish Fungi and Bacteria.
- 2009
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Ingår i: Microbial Ecology. - : Springer Science and Business Media LLC. - 1432-184X .- 0095-3628. ; 58:1, s. 75-85
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Tidskriftsartikel (refereegranskat)abstract
- The selective inhibition (SI) technique has been widely used to resolve fungal and bacterial biomass. By studying bacterial growth (leucine/thymidine incorporation) and respiration simultaneously, this study demonstrates that the inhibitors the SI technique is based on do not efficiently or specifically resolve fungal and bacterial contributions to respiration. At concentrations that completely inhibited bacterial growth, the bactericide streptomycin had no influence on the SI technique's respiration measurement, and complete inhibition of bacterial growth using oxytetracycline resulted in marginal respiration reductions. The fungicides captan and benomyl severely inhibited non-target bacterial growth. Cycloheximide did not reduce bacterial growth at moderate concentrations, but the cycloheximide respiration reduction was no higher in a soil with more fungal biomass, casting doubt on its ability to discriminate fungal respiration contribution. Conclusions regarding bacteria and fungi based on the SI technique using these inhibitors are thus compromised. The inhibition of glucose-activated respiration by the bactericide bronopol appeared to correlate with bacterial growth inhibition, however. Bronopol, combined with growth-based techniques, could aid development of a new framework to resolve decomposer ecology in soil.
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| 10. |
- Rousk, Johannes, et al.
(författare)
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Examining the fungal and bacterial niche overlap using selective inhibitors in soil.
- 2008
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 1574-6941 .- 0168-6496. ; 63:3, s. 350-358
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Tidskriftsartikel (refereegranskat)abstract
- It is important to know the contributions of bacteria and fungi to decomposition in connection with both the structure of the food web and the functioning of the ecosystem. However, the extent of the competition between these groups of organisms is largely unknown. The bacterial influence on fungal growth in a soil system was studied by applying three different bacterial inhibitors - bronopol, tylosin and oxytetracycline - in a series of increasing concentrations, and comparing the resulting bacterial and fungal growth rates measured using leucine and acetate-in-ergosterol incorporation, respectively. Direct measurements of growth showed that fungi increased after adding inhibitors; the level of increase in fungal growth corresponded to that of the decrease in bacterial growth, irrespective of the bacterial inhibitor used. Similar antagonistic effects of the bacteria on fungal growth were also found after adding the bacterial inhibitors together with additional substrate (alfalfa or straw plant material). The resulting responses in bacterial and fungal growth indirectly indicated that the negative interaction between fungi and bacteria was mostly attributable to exploitation competition. The results of this study also emphasize the increased sensitivity of using growth-related, instead of biomass-based, measurements when studying bacterial and fungal interactions in soil.
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