| 1. |
- Dicksved, Johan, et al.
(författare)
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Molecular analysis of the gut microbiota of identical twins with Crohn's disease
- 2008
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Ingår i: The ISME Journal. - : Nature Publishing Group. - 1751-7362 .- 1751-7370. ; 2:7, s. 716-727
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Tidskriftsartikel (refereegranskat)abstract
- Increasing evidence suggests that a combination of host genetics and the composition of the gut microbiota are important for development of Crohn's disease (CD). Our aim was to study identical twins with CD to determine microbial factors independent of host genetics. Fecal samples were studied from 10 monozygotic twin pairs with CD (discordant n=6 and concordant n=4) and 8 healthy twin pairs. DNA was extracted, 16S rRNA genes were PCR amplified and T-RFLP fingerprints generated using general bacterial and Bacteroides group-specific primers. The microbial communities were also profiled based on their percentage G+C contents. Bacteroides 16S rRNA genes were cloned and sequenced from a subset of the samples. The bacterial diversity in each sample and similarity indices between samples were estimated based on the T-RFLP data using a combination of statistical approaches. Healthy individuals had a significantly higher bacterial diversity compared to individuals with CD. The fecal microbial communities were more similar between healthy twins than between twins with CD, especially when these were discordant for the disease. The microbial community profiles of individuals with ileal CD were significantly different from healthy individuals and those with colonic CD. Also, CD individuals had a lower relative abundance of B. uniformis and higher relative abundances of B. ovatus and B. vulgatus. Our results suggest that genetics and/or environmental exposure during childhood, in part, determine the gut microbial composition. However, CD is associated with dramatic changes in the gut microbiota and this was particularly evident for individuals with ileal CD.
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| 2. |
- Edlund, Anna, et al.
(författare)
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Active bacterial community structure along vertical redox gradients in Baltic Sea sediment
- 2008
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Ingår i: Environmental Microbiology. - United Kingdom : Wiley-Blackwell Publishing Ltd.. - 1462-2912 .- 1462-2920. ; 10:8, s. 2051-2063
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Tidskriftsartikel (refereegranskat)abstract
- Community structures of active bacterial populations were investigated along a vertical redox profile in coastal Baltic Sea sediments by terminal-restriction fragment length polymorphism (T-RFLP) and clone library analysis. According to correspondence analysis of T-RFLP results and sequencing of cloned 16S rRNA genes, the microbial community structures at three redox depths (179, -64 and -337 mV) differed significantly. The bacterial communities in the community DNA differed from those in bromodeoxyuridine (BrdU)-labelled DNA, indicating that the growing members of the community that incorporated BrdU were not necessarily the most dominant members. The structures of the actively growing bacterial communities were most strongly correlated to organic carbon followed by total nitrogen and redox potentials. Bacterial identification by sequencing of 16S rRNA genes from clones of BrdU-labelled DNA and DNA from reverse transcription polymerase chain reaction showed that bacterial taxa involved in nitrogen and sulfur cycling were metabolically active along the redox profiles. Several sequences had low similarities to previously detected sequences, indicating that novel lineages of bacteria are present in Baltic Sea sediments. Also, a high number of different 16S rRNA gene sequences representing different phyla were detected at all sampling depths.
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| 3. |
- Edlund, Anna, et al.
(författare)
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Changes in active bacterial communities before and after dredging of highly polluted Baltic Sea sediments
- 2006
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 72:10, s. 6800-6807
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Tidskriftsartikel (refereegranskat)abstract
- Bacteria residing in sediments have key functions in the marine food web. However, it has been difficult to correlate the identity and activity of bacteria in sediments due to lack of appropriate methods beyond cultivation-based techniques. Our aim was to use a combination of molecular approaches, bromodeoxyuridine incorporation and immunocapture, terminal restriction fragment length polymorphism, and cloning and sequencing of 16S rRNA genes to assess the composition of growing bacteria in Baltic Sea sediments. The study site was a highly polluted area off the Swedish coast. The sediments were sampled in two consecutive years, before and after remediation, by dredging of the top sediments. Levels of polyaromatic hydrocarbons (PAHs), mercury, and polychlorinated biphenyls were dramatically reduced as a result of the cleanup project. The compositions of growing members of the communities were significantly different at the two sampling periods. In particular, members from the class Deltaproteobacteria and genus Spirochaeta were more dominant before dredging, but members of the classes Gammaproteobacteria and the Flavobacteria represented the most dominant growing populations after dredging. We also cultivated isolates from the polluted sediments that could transform the model PAH compound, phenanthrene. Some of these isolates were confirmed as dominant growing populations by the molecular methods as well. This suite of methods enabled us to link the identity and activity of the members of the sediment communities.
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| 4. |
- Edlund, Anna
(författare)
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Microbial diversity in Baltic Sea sediments
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on microbial community structures and their functions in Baltic Sea sediments. First we investigated the distribution of archaea and bacteria in Baltic Sea sediments along a eutrophication gradient. Community profile analysis of 16S rRNA genes using terminal restriction length polymorphism (T-RFLP) indicated that archaeal and bacterial communities were spatially heterogeneous. By employing statistical ordination methods we observed that archaea and bacteria were structured and impacted differently by environmental parameters that were significantly linked to eutrophication. In a separate study, we analyzed bacterial communities at a different site in the Baltic Sea that was heavily contaminated with polyaromatic hydrocarbons (PAHs) and several other pollutants. Sediment samples were collected before and after remediation by dredging in two consecutive years. A polyphasic experimental approach was used to assess growing bacteria and degradation genes in the sediments. The bacterial communities were significantly different before and after dredging of the sediment. Several isolates collected from contaminated sediments showed an intrinsic capacity for degradation of phenanthrene (a PAH model compound). Quantititative real-time PCR was used to monitor the abundance of degradation genes in sediment microcosms spiked with phenanthrene. Although both xylE and phnAc genes increased in abundance in the microcosms, the isolates only carried phnAc genes. Isolates with closest 16S rRNA gene sequence matches to Exigobacterium oxidotolerans, a Pseudomonas sp. and a Gammaproteobacterium were identified by all approaches used as growing bacteria that are capable of phenanthrene degradation. These isolates were assigned species and strain designations as follows: Exiguobacterium oxidotolerans AE3, Pseudomonas fluorescens AE1 and Pseudomonas migulae AE2. We also identified and studied the distribution of actively growing bacteria along red-ox profiles in Baltic Sea sediments. Community structures were found to be significantly different at different red-ox depths. Also, according to multivariate statistical ordination analysis organic carbon, nitrogen, and red-ox potential were crucial parameters for structuring the bacterial communities on a vertical scale. Novel lineages of bacteria were obtained by sequencing 16S rRNA genes from different red-ox depths and sampling stations indicating that bacterial diversity in Baltic Sea sediments is largely unexplored.
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| 5. |
- Edlund, Anna, et al.
(författare)
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Use of bromodeoxyuridine immunocapture to identify psychrotolerant phenanthrene-degrading bacteria in phenanthrene-enriched polluted Baltic Sea sediments
- 2008
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Ingår i: FEMS Microbiology Ecology. - : Oxford University Press (OUP). - 0168-6496 .- 1574-6941. ; 65:3, s. 513-525
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to enrich and identify psychrotolerant phenanthrene-degrading bacteria from polluted Baltic Sea sediments. Polyaromatic hydrocarbon (PAH)-contaminated sediments were spiked with phenanthrene and incubated for 2 months in the presence of bromodeoxyuridine that is incorporated into the DNA of replicating cells. The bromodeoxyuridine-incorporated DNA was extracted by immunocapture and analyzed by terminal-restriction fragment length polymorphism and 16S rRNA gene cloning and sequencing to identify bacterial populations that were growing. In addition, degradation genes were quantified in the bromodeoxyuridine-incorporated DNA by real-time PCR. Phenanthrene concentrations decreased after 2 months of incubation in the phenanthrene-enriched sediments and this reduction correlated to increases in copy numbers of xylE and phnAc dioxygenase genes. Representatives of Exiguobacterium, Schewanella, Methylomonas, Pseudomonas, Bacteroides and an uncultured Deltaproteobacterium and a Gammaproteobacterium dominated the growing community in the phenanthrene-spiked sediments. Isolates that were closely related to three of these bacteria (two pseudomonads and an Exiguobacterium sp.) could reduce phenanthrene concentrations in pure cultures and they all harbored phnAc dioxygenase genes. These results confirm that this combination of culture-based and molecular approaches was useful for identification of actively growing bacterial species with a high potential for phenanthrene degradation.
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| 6. |
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| 7. |
- Hjort, Karin, et al.
(författare)
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Community structure of actively growing bacterial populations in plant pathogen suppressive soil.
- 2007
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Ingår i: Microbial Ecology. - : Springer Science and Business Media LLC. - 0095-3628 .- 1432-184X. ; 53:3, s. 399-413
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Tidskriftsartikel (refereegranskat)abstract
- The bacterial community in soil was screened by using various molecular approaches for bacterial populations that were activated upon addition of different supplements. Plasmodiophora brassicae spores, chitin, sodium acetate, and cabbage plants were added to activate specific bacterial populations as an aid in screening for novel antagonists to plant pathogens. DNA from growing bacteria was specifically extracted from the soil by bromodeoxyuridine immunocapture. The captured DNA was fingerprinted by terminal restriction fragment length polymorphism (T-RFLP). The composition of the dominant bacterial community was also analyzed directly by T-RFLP and by denaturing gradient gel electrophoresis (DGGE). After chitin addition to the soil, some bacterial populations increased dramatically and became dominant both in the total and in the actively growing community. Some of the emerging bands on DGGE gels from chitin-amended soil were sequenced and found to be similar to known chitin-degrading genera such as Oerskovia, Kitasatospora, and Streptomyces species. Some of these sequences could be matched to specific terminal restriction fragments on the T-RFLP output. After addition of Plasmodiophora spores, an increase in specific Pseudomonads could be observed with Pseudomonas-specific primers for DGGE. These results demonstrate the utility of microbiomics, or a combination of molecular approaches, for investigating the composition of complex microbial communities in soil.
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| 8. |
- Jernberg, Cecilia, et al.
(författare)
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Long-term ecological impacts of antibiotic administration on the human intestinal microbiota
- 2007
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Ingår i: The ISME Journal. - : Springer Science and Business Media LLC. - 1751-7362 .- 1751-7370. ; 1:1, s. 56-66
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Tidskriftsartikel (refereegranskat)abstract
- Antibiotic administration is known to cause short-term disturbances in the microbiota of the human gastrointestinal tract, but the potential long-term consequences have not been well studied. The aims of this study were to analyse the long-term impact of a 7-day clindamycin treatment on the faecal microbiota and to simultaneously monitor the ecological stability of the microbiota in a control group as a baseline for reference. Faecal samples from four clindamycin-exposed and four control subjects were collected at nine different time points over 2 years. Using a polyphasic approach, we observed highly significant disturbances in the bacterial community that persisted throughout the sampling period. In particular, a sharp decline in the clonal diversity of Bacteroides isolates, as assessed by repetitive sequence-based PCR (rep-PCR) and long-term persistence of highly resistant clones were found as a direct response to the antibiotic exposure. The Bacteroides community never returned to its original composition during the study period as assessed using the molecular fingerprinting technique, terminal restriction fragment length polymorphism (T-RFLP). Furthermore, using real-time PCR we found a dramatic and persistent increase in levels of specific resistance genes in DNA extracted from the faeces after clindamycin administration. The temporal variations in the microbiota of the control group were minor compared to the large and persistent shift seen in the exposed group. These results demonstrate that long after the selection pressure from a short antibiotic exposure has been removed, there are still persistent long term impacts on the human intestinal microbiota that remain for up to 2 years post-treatment.
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| 9. |
- Jernberg, Cecilia
(författare)
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Use of microbiomics to study human impacts on complex microbial communities
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study of bacterial communities in nature is currently a challenge. The majority of bacteria in clinical and environmental samples have not yet been cultured and therefore we cannot fully understand their roles in nature and how the ecological balance in a specific microbial ecosystem can be disrupted. For example, exposure to pollutants in soil and antibiotics in the human gut can have large consequences on microbial populations but the magnitude of these impacts is difficult to assess. In this thesis, a combination of molecular techniques, microbiomics, were used to assess complex microbial communities in soil and the human gut. One goal of this thesis was to study the impact of the toxic compound, 4-chlorophenol, on the soil microbiota. In addition, a specific 4-chlorophenol degrading bacterium, Arthrobacter chlorophenolicus, was monitored in soil. In order to monitor the cells they were chromosomally tagged with marker genes encoding either the green fluorescent protein (the gfp gene) or firefly luciferase (the luc gene). During degradation of high levels of 4-chlorophenol in soil, total cells counts of A. chlorophenolicus cells could be measured by flow cytometry (GFP protein) and the metabolic activity could be measured by lurninometry (luciferase activity). In addition, the relative abundance of A. chlorophenolicus in soil could be measured by terminal restriction fragment length polymorphism (T-RFLP) and a higher relative abundance was detected in soil contaminated with 4chlorophenol compared with non-treated soil. The impacts of 4-chlorophenol and A. chlorophenolicus on the dominant members of the soil microbiota were also assessed by T-RFLP. Another goal of this thesis was to study the impact of a short term antibiotic administration in a long term perspective, using either clindamycin, in a two year study or a triple therapy for eradication of Helicobacter pylori containing clarithromycin and metronidazole, in a four year study, on the human fecal microbiota. Both the total bacterial community and specific populations, i.e. Bacteroides spp. and Enterococcus spp., were monitored by T-RFLP. The Bacteroides populations never returned to their pre-treatment composition after clindamycin exposure during the two year study period. Selection and persistence of resistant Bacteroides clones up to two years after treatment was furthermore detected. In the four year study, Enterococcus populations increased as a response to the clarithromycin and metronidazole treatment. An increase in the levels of antibiotic resistance genes, specific erm genes, conferring resistance to macrolides and lincosamides were detected for up to 2 and 4 years after both types of antibiotic treatments in the respective studies. It was also possible to specifically monitor two probiotic Lactobacillus strains and their transient colonization by T-RFLP. In conclusion, the use of a polyphasic approach with complementary analytical tools made it possible to obtain a comprehensive picture of complex microbial communities. In addition, specific bacteria of interest in complex soil and fecal samples could be monitored using microbiomics approaches.
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| 10. |
- Löfmark, Sonja, et al.
(författare)
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Clindamycin-induced enrichment and long-term persistence of resistant Bacteroides spp. and resistance genes
- 2006
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 0305-7453 .- 1460-2091. ; 58:6, s. 1160-1167
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim was to study the long-term consequences of 1 week clindamycin administration regarding selection and persistence of resistance, resistance determinants and diversity of the Bacteroides spp. in the intestinal microflora. Methods: A total of 1306 Bacteroides isolates were collected from constitutively cultured faecal samples during a 2 year period from eight healthy volunteers. The strains were identified by biochemical and genotyping methods. MIC values were determined by the agar dilution method and presence of resistance genes was screened by real-time PCR. Results: Ecological changes in the intestinal microflora persisting up to 24 months were recorded after a 7 day clindamycin administration to four healthy volunteers. Compared to a control group, not exposed to clindamycin, an enrichment and stabilization of resistant Bacteroides strains and resistance determinants were discovered up to 2 years after clindamycin exposure. Conclusions: The results indicate that even a short-term antibiotic administration can cause long-term alterations in the commensal microbiota of individual subjects, detectable 2 years after dosing. The recorded selection and persistence of resistant strains and resistance genes, illustrates the importance of increasing our knowledge of the role of the abundant intestinal microbial community as a reservoir for spread of resistance.
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| 11. |
- Maraha, Ninwe
(författare)
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Physiological status of bacteria used for environmental applications
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Several bacteria have properties of interest for biotechnological applications, such as bioremediation of pollutants and biocontrol of plant pathogens. In order to perform their intended tasks in the environment the cells need to remain viable and active. Therefore, the aim of this thesis was to use a combination of molecular approaches to determine the physiological status of specific bacterial populations in soil. Complementary experiments were done in pure cultures to gain a better understanding of specific physiological states, such as bacterial dormancy. In some studies, the bacteria were tagged with the following marker genes to enable them to be specifically detected in soil: gfp (encoding the green fluorescent protein, GFP), luxAB (encoding bacterial luciferase) or luc (encoding eukaryotic luciferase). Viability stains, 5-cyano-2,3-ditolyl-tetrazolium chloride (CTC) and propidium iodide (PI), were used to stain active and dead cells, respectively. The marker-gene tagged cells were incubated in soil under different conditions and the number of GFP fluorescent and stained cells was enumerated by flow cytometry at specified sampling periods. Luciferase activity was used to monitor metabolic activity of the population. In addition, the number of culturable cells was determined by selective plate counting and compared to the results obtained by flow cytometry. Finally, in one study, proteomics was used to elucidate which proteins were expressed under different nutrient conditions. The physiological status of Arthrobacter chlorophenolicus A6 (a chlorophenol degrading bacterium) was investigated after introduction into soil incubated at different temperatures, 5 and 28 °C. The majority of the A6 population remained metabolically active after 20 days of incubation in soil at 5 °C. However, there was a fraction of the GFP-fluorescent A6 population that was not stained with CTC or PI, presumably indicating a subfraction of dormant cells that were alive but inactive. By contrast, after the same period of incubation at 28 °C, the majority of the cells died. The ability of A. chlorophenolicus A6 to enter a state of dormancy during incubation at cold temperatures, makes this strain a good candidate for treating chlorophenol contaminated soil in temperate climates. Two Pseudomonas fluorescens strains, proposed for improving crop yields, were also studied. Pseudomonas fluoresens A506 is used to reduce frost damage to plants and Pseudomonas fluorescens SBW25 is a plant growth promoting bacterium. First, a GFPtagged variant of the A506 strain was studied to determine whether GFP could be used to detect the cells when they were viable but non-culturable (VBNC). The results showed that GFP tagged cells could be detected even in a V13NC state as long as the cell membrane was intact. The SBW25 strain was studied in pure cultures and in soil to determine the physiological status of the cells under different nutritional conditions, using many of the approaches described above for A6. Most of the cells died after incubation for nine days in nutrient rich medium. By contrast when incubated under starvation conditions, most of the population was not stained with CTC or PI, indicating that most of the cells were presumably dormant. In soil, a subpopulation of the SBW25 cell population died. However, approximately 60% of the population in soil apparently entered a state of dormancy, similar to that observed under starvation conditions in pure cultures. Several differences were found in the proteins that were expressed when SBW25 was incubated under nutrient rich conditions compared to starvation conditions. These differences provide a clue as to what proteins enable SBW25 to survive starvation and dormant states.
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| 12. |
- Nordin, Karolina, et al.
(författare)
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Novel 4-chlorophenol degradation gene cluster and degradation route via hydroxyquinol in Arthrobacter chlorophenolicus A6
- 2005
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Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 71:11, s. 6538-6544
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Tidskriftsartikel (refereegranskat)abstract
- Arthrobacter chlorophenolicus A6, a previously described 4-chlorophenol-degrading strain, was found to degrade 4-chlorophenol via hydroxyquinol, which is a novel route for aerobic microbial degradation of this compound. In addition, 10 open reading frames exhibiting sequence similarity to genes encoding enzymes involved in chlorophenol degradation were cloned and designated part of a chlorophenol degradation gene cluster (cph genes). Several of the open reading frames appeared to encode enzymes with similar functions; these open reading frames included two genes, cphA-I and cphA-H, which were shown to encode functional hydroxyquinol 1,2-dioxygenases. Disruption of the cphA-I gene yielded a mutant that exhibited negligible growth on 4-chlorophenol, thereby linking the cph gene cluster to functional catabolism of 4-chlorophenol in A. chlorophenolicus A6. The presence of a resolvase pseudogene in the cph gene cluster together with analyses of the G+C content and codon bias of flanking genes suggested that horizontal gene transfer was involved in assembly of the gene cluster during evolution of the ability of the strain to grow on 4-chlorophenol.
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| 13. |
- Steger, Kristin, et al.
(författare)
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Development of compost maturity and Actinobacteria populations during full-scale composting of organic household waste
- 2007
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Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 103:2, s. 487-498
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: This study investigates changes in microbiological and physicochemical parameters during large-scale, thermophilic composting of a single batch of municipal organic waste. The inter-relationships between the microbial biomass and community structure as well as several physicochemical parameters and estimates of maturation were evaluated. METHODS AND RESULTS: Analyses of signature fatty acids with the phospholipid fatty acid and ester-linked methods showed that the total microbial biomass was highest during the early thermophilic phase. The contribution of signature 10Me fatty acids from Actinobacteria indicated a relatively constant proportion around 10% of the microbial community. However, analyses of the Actinobacteria species composition with a PCR-denaturing gradient gel electrophoresis approach targeting 16S rRNA genes demonstrated clear shifts in the community structure. CONCLUSIONS: This study demonstrates that compost quality, particularly maturity, is linked to the composition of the microbial community structure, but further studies in other full-scale systems are needed to validate the generality of these findings. SIGNIFICANCE AND IMPACT OF THE STUDY: The combination of signature lipid and nucleic acid-based analyses greatly expands the specificity and the scope for assessing the microbial community composition in composts. The results presented in this study give new information on how the development of the compost microbial community is connected to curing and maturation in the later stages of composting, and emphasizes the role of Actinobacteria in this respect.
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| 14. |
- Unell, Maria, et al.
(författare)
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Degradation of mixtures of phenolic compounds by Arthrobacter chlorophenolicus A6
- 2008
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Ingår i: Biodegradation. - : Springer Science and Business Media LLC. - 0923-9820 .- 1572-9729. ; 19:4, s. 495-505
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Tidskriftsartikel (refereegranskat)abstract
- In this study the chlorophenol-degrading actinobacterium, Arthrobacter chlorophenolicus A6, was tested for its ability to grow on mixtures of phenolic compounds. During the experiments depletion of the compounds was monitored, as were cell growth and activity. Activity assays were based on bioluminescence output from a luciferase-tagged strain. When the cells were grown on a mixture of 4-chlorophenol, 4-nitrophenol and phenol, 4-chlorophenol degradation apparently was delayed until 4-nitrophenol was almost completely depleted. Phenol was degraded more slowly than the other compounds and not until 4-nitrophenol and 4-chlorophenol were depleted, despite this being the least toxic compound of the three. A similar order of degradation was observed in non-sterile soil slurries inoculated with A. chlorophenolicus. The kinetics of degradation of the substituted phenols suggest that the preferential order of their depletion could be due to their respective pKa values and that the dissociated phenolate ions are the substrates. A mutant strain (T99), with a disrupted hydroxyquinol dioxygenase gene in the previously described 4-chlorophenol degradation gene cluster, was also studied for its ability to grow on the different phenols. The mutant strain was able to grow on phenol, but not on either of the substituted phenols, suggesting a different catabolic pathway for the degradation of phenol by this microorganism.
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| 15. |
- von der Weid, Irene, et al.
(författare)
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Antifungal and root surface colonization properties of GFP-tagged Paenibacillus brasilensis PB177
- 2005
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Ingår i: World Journal of Microbiology & Biotechnology. - : Springer Science and Business Media LLC. - 0959-3993 .- 1573-0972. ; 21:8-9, s. 1591-1597
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Tidskriftsartikel (refereegranskat)abstract
- This study evaluates the potential of Paenibacillus brasilensis strain PB177 to inhibit phytopathogenic fungi commonly causing maize diseases and to colonize maize plants. In vitro assays demonstrated antagonistic activity against the fungal pathogens, Fusarium moniliforme and Diplodia macrospora. The PB177 strain was tagged with the gfp gene, encoding the green fluorescent protein (GFP) and GFP-tagged bacteria were detected attached to maize roots by stereo- and confocal microscopy. The GFP-tagged bacteria were also used to treat maize seeds before challenging the seeds with two phytopathogenic fungi. The results demonstrated that the bacterial cells are mobilized to the maize roots in the presence of the fungal pathogens. The ability of P. brasilensis PB177 to inhibit fungal growth in vitro and its capability of colonization of maize roots in vivo suggest a potential application of this strain as a biological control agent. This is the first report on the successful introduction of the GFP marker gene into a P. brasilensis strain, enabling the direct observation of these promising plant growth promoting bacteria on maize roots in situ.
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