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Fabrice Martin-laurent - One of the best experts on this subject based on the ideXlab platform.
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Isolation and characterization of an isoproturon mineralizing Sphingomonas sp. strain SH from a French Agricultural Soil
Biodegradation, 2011Co-Authors: Sabir Hussain, Marion Devers-lamrani, Najoi El Azhari, Fabrice Martin-laurentAbstract:The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized in an Agricultural Soil in France that had been periodically exposed to IPU. Enrichment cultures from samples of this Soil isolated a bacterial strain able to mineralize IPU. 16S rRNA sequence analysis showed that this strain belonged to the phylogeny of the genus Sphingomonas (96% similarity with Sphingomonas sp. JEM-14, AB219361) and was designated Sphingomonas sp. strain SH. From this strain, a partial sequence of a 1,2-dioxygenase ( catA ) gene coding for an enzyme degrading catechol putatively formed during IPU mineralization was amplified. Phylogenetic analysis revealed that the catA sequence was related to Sphingomonas spp. and showed a lack of congruence between the catA and 16S rRNA based phylogenies, implying horizontal gene transfer of the catA gene cluster between Soil microbiota. The IPU degrading ability of strain SH was strongly influenced by pH with maximum degradation taking place at pH 7.5. SH was only able to mineralize IPU and its known metabolites including 4-isopropylaniline and it could not degrade other structurally related phenylurea herbicides such as diuron, linuron, monolinuron and chlorotoluron or their aniline derivatives. These observations suggest that the catabolic abilities of the strain SH are highly specific to the metabolism of IPU.
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Characterization of an isoproturon mineralizing bacterial culture enriched from a French Agricultural Soil
Chemosphere, 2009Co-Authors: Sabir Hussain, Talaat El-sebai, Marion Devers-lamrani, Sebastian R Sorensen, Fabrice Martin-laurentAbstract:The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized by a bacterial culture isolated from an Agricultural Soil regularly exposed to IPU. Molecular analysis of the bacterial culture by DNA fingerprinting, cloning and sequencing of the 16S rRNA genes revealed that it consisted of six different members among whom the dominant was related to Sphingomonas sp. Six bacterial strains belonging to genera Ancylobacter, Pseudomonas, Stenotrophomonas, Methylobacterium, Variovorax and Agrobacterium were isolated from the IPU-degrading culture. None of these were able to degrade IPU in pure culture and only the intact culture sustained the ability to mineralize IPU. The composition of the culture appeared stable suggesting that yet unknown interactions are involved in the IPU mineralization. IPU degradation involved the transitory accumulation of three known IPU metabolites 3-(4-isopropylphenyl)-1-methylurea, 3-(4-isopropylphenyl)-urea, and 4-isopropylaniline and their further degradation. Thus, it indicates a metabolic pathway initiated by two successive N-demethylations, followed by cleavage of the urea side chain. This culture did not degrade other structurally related phenylurea herbicides. The degrading activity of the bacterial culture was deeply influenced by the pH, being completely inhibited at pH 5.5 and optimal at pH 7.5.
Manyun Zhang - One of the best experts on this subject based on the ideXlab platform.
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antagonistic effects of nitrification inhibitor 3 4 dimethylpyrazole phosphate and fungicide iprodione on net nitrification in an Agricultural Soil
Soil Biology & Biochemistry, 2018Co-Authors: Manyun Zhang, Weijin Wang, Shahla Hosseini Bai, Xue Zhou, Ying TengAbstract:This study evaluated the effects of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) and fungicide iprodione on net nitrification rates and abundances of functional genes related to nitrification and denitrification in an Agricultural Soil. Single DMPP application or repeated iprodione applications decreased net nitrification rates in the test Soil. However, when the DMPP and iprodione were applied together, they could generate antagonistic effects on the inhibitions of net nitrification rates. Repeated iprodione applications reduced ammonia-oxidizing archaea and bacteria (AOA and AOB) amoA gene abundances, while DMPP application decreased AOB amoA gene abundances only. The abundances of narG and nirK genes were negatively affected by repeated iprodione applications. Our results demonstrated that combined applications of DMPP and iprodione could generate antagonistic effects on the inhibitions of net nitrification rates and discrepant impacts on the abundances of functional genes related to Soil denitrification.
Sabir Hussain - One of the best experts on this subject based on the ideXlab platform.
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Isolation and characterization of an isoproturon mineralizing Sphingomonas sp. strain SH from a French Agricultural Soil
Biodegradation, 2011Co-Authors: Sabir Hussain, Marion Devers-lamrani, Najoi El Azhari, Fabrice Martin-laurentAbstract:The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized in an Agricultural Soil in France that had been periodically exposed to IPU. Enrichment cultures from samples of this Soil isolated a bacterial strain able to mineralize IPU. 16S rRNA sequence analysis showed that this strain belonged to the phylogeny of the genus Sphingomonas (96% similarity with Sphingomonas sp. JEM-14, AB219361) and was designated Sphingomonas sp. strain SH. From this strain, a partial sequence of a 1,2-dioxygenase ( catA ) gene coding for an enzyme degrading catechol putatively formed during IPU mineralization was amplified. Phylogenetic analysis revealed that the catA sequence was related to Sphingomonas spp. and showed a lack of congruence between the catA and 16S rRNA based phylogenies, implying horizontal gene transfer of the catA gene cluster between Soil microbiota. The IPU degrading ability of strain SH was strongly influenced by pH with maximum degradation taking place at pH 7.5. SH was only able to mineralize IPU and its known metabolites including 4-isopropylaniline and it could not degrade other structurally related phenylurea herbicides such as diuron, linuron, monolinuron and chlorotoluron or their aniline derivatives. These observations suggest that the catabolic abilities of the strain SH are highly specific to the metabolism of IPU.
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Characterization of an isoproturon mineralizing bacterial culture enriched from a French Agricultural Soil
Chemosphere, 2009Co-Authors: Sabir Hussain, Talaat El-sebai, Marion Devers-lamrani, Sebastian R Sorensen, Fabrice Martin-laurentAbstract:The phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was found to be rapidly mineralized by a bacterial culture isolated from an Agricultural Soil regularly exposed to IPU. Molecular analysis of the bacterial culture by DNA fingerprinting, cloning and sequencing of the 16S rRNA genes revealed that it consisted of six different members among whom the dominant was related to Sphingomonas sp. Six bacterial strains belonging to genera Ancylobacter, Pseudomonas, Stenotrophomonas, Methylobacterium, Variovorax and Agrobacterium were isolated from the IPU-degrading culture. None of these were able to degrade IPU in pure culture and only the intact culture sustained the ability to mineralize IPU. The composition of the culture appeared stable suggesting that yet unknown interactions are involved in the IPU mineralization. IPU degradation involved the transitory accumulation of three known IPU metabolites 3-(4-isopropylphenyl)-1-methylurea, 3-(4-isopropylphenyl)-urea, and 4-isopropylaniline and their further degradation. Thus, it indicates a metabolic pathway initiated by two successive N-demethylations, followed by cleavage of the urea side chain. This culture did not degrade other structurally related phenylurea herbicides. The degrading activity of the bacterial culture was deeply influenced by the pH, being completely inhibited at pH 5.5 and optimal at pH 7.5.
Ying Teng - One of the best experts on this subject based on the ideXlab platform.
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antagonistic effects of nitrification inhibitor 3 4 dimethylpyrazole phosphate and fungicide iprodione on net nitrification in an Agricultural Soil
Soil Biology & Biochemistry, 2018Co-Authors: Manyun Zhang, Weijin Wang, Shahla Hosseini Bai, Xue Zhou, Ying TengAbstract:This study evaluated the effects of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) and fungicide iprodione on net nitrification rates and abundances of functional genes related to nitrification and denitrification in an Agricultural Soil. Single DMPP application or repeated iprodione applications decreased net nitrification rates in the test Soil. However, when the DMPP and iprodione were applied together, they could generate antagonistic effects on the inhibitions of net nitrification rates. Repeated iprodione applications reduced ammonia-oxidizing archaea and bacteria (AOA and AOB) amoA gene abundances, while DMPP application decreased AOB amoA gene abundances only. The abundances of narG and nirK genes were negatively affected by repeated iprodione applications. Our results demonstrated that combined applications of DMPP and iprodione could generate antagonistic effects on the inhibitions of net nitrification rates and discrepant impacts on the abundances of functional genes related to Soil denitrification.
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influence of arbuscular mycorrhiza and rhizobium on phytoremediation by alfalfa of an Agricultural Soil contaminated with weathered pcbs a field study
International Journal of Phytoremediation, 2010Co-Authors: Ying Teng, Yongming Luo, Xianghui Sun, Wuxing Liu, Peter ChristieAbstract:A field experiment was conducted to study the effects of inoculation with the arbuscular mycorrhizal fungus Glomus caledonium and/or Rhizobium meliloti on phytoremediation of an Agricultural Soil contaminated with weathered PCBs by alfalfa grown for 180 days. Planting alfalfa (P), alfalfa inoculated with G. caledonium (P+AM), alfalfa inoculated with R.meliloti(P+R),andalfalfaco-inoculatedwithR.melilotiandG.caledonium(P+AM+R) decreased significantly initial Soil PCB concentrations by 8.1, 12.0, 33.8, and 43.5%, respectively. Inoculation with R. meliloti and/or G. caledonium (P+AM+R) increased the yield of alfalfa, and the accumulation of PCBs in the shoots. Soil microbial counts and the carbon utilizationabilityoftheSoilmicrobialcommunityincreasedwhenalfalfawasinoculatedwith R. meliloti and/or G. caledonium. Results of this field study suggest that synergistic interactions between AMF and Rhizobium may have great potential to enhance phytoremediation by alfalfa of an Agricultural Soil contaminated with weathered PCBs.
Ralf Conrad - One of the best experts on this subject based on the ideXlab platform.
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simazine application inhibits nitrification and changes the ammonia oxidizing bacterial communities in a fertilized Agricultural Soil
FEMS Microbiology Ecology, 2011Co-Authors: Marcela Hernández, Ralf Conrad, Zhongjun Jia, Michael SeegerAbstract:s-Triazine herbicides are widely used for weed control, and are persistent in Soils. Nitrification is an essential process in the global nitrogen cycle in Soil, and involves ammonia-oxidizing Bacteria (AOB) and ammonia-oxidizing Archaea (AOA). In this study, we evaluated the effect of the s-triazine herbicide simazine on the nitrification and on the structure of ammonia-oxidizing microbial communities in a fertilized Agricultural Soil. The effect of simazine on AOB and AOA were studied by PCR-amplification of amoA genes of nitrifying Bacteria and Archaea in Soil microcosms and denaturing gradient gel electrophoresis (DGGE) analyses. Simazine [50 ?g g?1 dry weight Soil (d.w.s)] completely inhibited the nitrification processes in the fertilized Agricultural Soil. The inhibition by simazine of ammonia oxidation observed was similar to the reduction of ammonia oxidation by the nitrification inhibitor acetylene. The application of simazine-affected AOB community DGGE patterns in the Agricultural Soil amended with ammonium, whereas no significant changes in the AOA community were observed. The DGGE analyses strongly suggest that simazine inhibited Nitrosobacteria and specifically Nitrosospira species. In conclusion, our results suggest that the s-triazine herbicide not only inhibits the target susceptible plants but also inhibits the ammonia oxidation and the AOB in fertilized Soils.
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ammonia oxidation coupled to co2 fixation by archaea and bacteria in an Agricultural Soil
Proceedings of the National Academy of Sciences of the United States of America, 2011Co-Authors: Jennifer Pratscher, Marc G Dumont, Ralf ConradAbstract:Ammonia oxidation is an essential part of the global nitrogen cycling and was long thought to be driven only by bacteria. Recent findings expanded this pathway also to the archaea. However, most questions concerning the metabolism of ammonia-oxidizing archaea, such as ammonia oxidation and potential CO2 fixation, remain open, especially for terrestrial environments. Here, we investigated the activity of ammonia-oxidizing archaea and bacteria in an Agricultural Soil by comparison of RNA- and DNA-stable isotope probing (SIP). RNA-SIP demonstrated a highly dynamic and diverse community involved in CO2 fixation and carbon assimilation coupled to ammonia oxidation. DNA-SIP showed growth of the ammonia-oxidizing bacteria but not of archaea. Furthermore, the analysis of labeled RNA found transcripts of the archaeal acetyl-CoA/propionyl-CoA carboxylase (accA/pccB) to be expressed and labeled. These findings strongly suggest that ammonia-oxidizing archaeal groups in Soil autotrophically fix CO2 using the 3-hydroxypropionate–4-hydroxybutyrate cycle, one of the two pathways recently identified for CO2 fixation in Crenarchaeota. Catalyzed reporter deposition (CARD)-FISH targeting the gene encoding subunit A of ammonia monooxygenase (amoA) mRNA and 16S rRNA of archaea also revealed ammonia-oxidizing archaea to be numerically relevant among the archaea in this Soil. Our results demonstrate a diverse and dynamic contribution of ammonia-oxidizing archaea in Soil to nitrification and CO2 assimilation and that their importance to the overall archaeal community might be larger than previously thought.
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bacteria rather than archaea dominate microbial ammonia oxidation in an Agricultural Soil
Environmental Microbiology, 2009Co-Authors: Ralf ConradAbstract:Summary Agricultural ecosystems annually receive approximately 25% of the global nitrogen input, much of which is oxidized at least once by ammonia-oxidizing prokaryotes to complete the nitrogen cycle. Recent discoveries have expanded the known ammoniaoxidizing prokaryotes from the domain Bacteria to Archaea. However, in the complex Soil environment it remains unclear whether ammonia oxidation is exclusively or predominantly linked to Archaea as implied by their exceptionally high abundance. Here we show that Bacteria rather than Archaea functionally dominate ammonia oxidation in an Agricultural Soil, despite the fact that archaeal versus bacterial amoA genes are numerically more dominant. In Soil microcosms, in which ammonia oxidation was stimulated by ammonium and inhibited by acetylene, activity change was paralleled by abundance change of bacterial but not of archaeal amoA gene copy numbers. Molecular fingerprinting of amoA genes also coupled ammonia oxidation activity with bacterial but not archaeal amoA gene patterns. DNA-stable isotope probing demonstrated CO2 assimilation by Bacteria rather than Archaea. Our results indicate that Archaea were not important for ammonia oxidation in the Agricultural Soil tested.