Distribution of denitrification and nitrogen fixation genes inHyphomicrobiumspp. and other budding bacteria

1998 ◽  
Vol 44 (2) ◽  
pp. 181-186 ◽  
Author(s):  
A Fesefeldt ◽  
K Kloos ◽  
H Bothe ◽  
H Lemmer ◽  
C G Gliesche
Keyword(s):  
Nitrogen Fixation ◽  
Nitrite Reductase ◽  
Dna Hybridization ◽  
Treatment Plant ◽  
Gene Fragment ◽  
Ammonia Monooxygenase ◽  
Intact Cells ◽  
Activity Measurements ◽  
Denitrification Genes ◽  
Budding Bacteria

Genomic DNA of Hyphomicrobium spp., Hirschia baltica ATCC 49814T, Hyphomonas oceanitis ATCC 33897T, and Pedomicrobium ferrugineum S-1290Twas investigated with gene probes specific for nitrate reductase (narG), cytochrome cd1containing nitrite reductase (nirS), Cu-containing nitrite reductase (nirK), nitrous oxide reductase (nosZ), ammonia monooxygenase (amoA), and nitrogenase reductase (nifH) by Southern or dot blot hybridization. The presence of denitrification genes could be demonstrated for Hyphomicrobium denitrificans 1869T, Hyphomicrobium aestuarii IFAM NQ-521GrT, Hyphomicrobium zavarzinii IFAM ZV-580, Hyphomicrobium zavarzinii subsp. chengduense, in the Hyphomicrobium DNA-DNA hybridization groups 3, 12, 13, 18, 26a1, 26a2, 26c, 26d, 26e, 26f, 26g2, and 29, and in three isolates from a denitrifying sand filter in a municipal wastewater treatment plant. The Cu-containing nitrite reductase appeared to be more frequent than the cytochrome cd1containing nitrite reductase in hyphomicrobia. Resulting positive DNA-DNA hybridization signals correlated with physiological activity measurements of intact cells in all cases determined. The nifH-like gene fragment was found in Hyphomicrobium aestuarii, Hyphomicrobium zavarzinii, Hyphomicrobium zavarzinii subsp. chengduense, Hyphomicrobium facilis and eight additional DNA-DNA hybridization groups. Ammonia monooxygenase was not genetically detected in any of the strains investigated. The results significantly extended the previous findings that genetically different hyphomicrobia of a sewage treatment plant and its adjacent receiving lake could occupy different ecological niches. Denitrification genes or the nifH-like gene fragment were not found in the other budding bacteria investigated.Key words: Hyphomicrobium, denitrification, nitrification, nitrogen fixation, activated sludge, biofilm.

scholarly journals A Mutant of Paracoccus denitrificans with Disrupted Genes Coding for Cytochrome c550 and Pseudoazurin Establishes These Two Proteins as the In Vivo Electron Donors to Cytochrome cd1 Nitrite Reductase

2003 ◽  
Vol 185 (21) ◽  
pp. 6308-6315 ◽  
Author(s):  
Isobel V. Pearson ◽  
M. Dudley Page ◽  
Rob J. M. van Spanning ◽  
Stuart J. Ferguson
Keyword(s):  
Nitrite Reductase ◽  
Paracoccus Denitrificans ◽  
Wild Type ◽  
Anaerobic Conditions ◽  
Electron Mediator ◽  
Intact Cells ◽  
Cytochrome Cd1 ◽  
Membrane Bound ◽  
Electron Carriers

ABSTRACT In Paracoccus denitrificans, electrons pass from the membrane-bound cytochrome bc 1 complex to the periplasmic nitrite reductase, cytochrome cd 1. The periplasmic protein cytochrome c 550 has often been implicated in this electron transfer, but its absence, as a consequence of mutation, has previously been shown to result in almost no attenuation in the ability of the nitrite reductase to function in intact cells. Here, the hypothesis that cytochrome c 550 and pseudoazurin are alternative electron carriers from the cytochrome bc 1 complex to the nitrite reductase was tested by construction of mutants of P. denitrificans that are deficient in either pseudoazurin or both pseudoazurin and cytochrome c 550. The latter organism, but not the former (which is almost indistinguishable in this respect from the wild type), grows poorly under anaerobic conditions with nitrate as an added electron acceptor and accumulates nitrite in the medium. Growth under aerobic conditions with either succinate or methanol as the carbon source is not significantly affected in mutants lacking either pseudoazurin or cytochrome c 550 or both these proteins. We concluded that pseudoazurin and cytochrome c 550 are the alternative electron mediator proteins between the cytochrome bc 1 complex and the cytochrome cd 1-type nitrite reductase. We also concluded that expression of pseudoazurin is mainly controlled by the transcriptional activator FnrP.

scholarly journals Kinetics of nirS Expression (Cytochromecd1 Nitrite Reductase) in Pseudomonas stutzeri during the Transition from Aerobic Respiration to Denitrification: Evidence for a Denitrification-Specific Nitrate- and Nitrite-Responsive Regulatory System

1999 ◽  
Vol 181 (1) ◽  
pp. 161-166 ◽  
Author(s):  
Elisabeth Härtig ◽  
Walter G. Zumft
Keyword(s):  
Nitrite Reductase ◽  
Response Regulator ◽  
Gene Activation ◽  
Regulatory System ◽  
Pseudomonas Stutzeri ◽  
Low Oxygen ◽  
Gene Encoding ◽  
Regulatory Circuit ◽  
Nitrate And Nitrite ◽  
Denitrification Genes

ABSTRACT After shifting an oxygen-respiring culture of Pseudomonas stutzeri to nitrate or nitrite respiration, we directly monitored the expression of the nirS gene by mRNA analysis.nirS encodes the 62-kDa subunit of the homodimeric cytochrome cd 1 nitrite reductase involved in denitrification. Information was sought about the requirements for gene activation, potential regulators of such activation, and signal transduction pathways triggered by the alternative respiratory substrates. We found that nirS, together withnirT and nirB (which encode tetra- and diheme cytochromes, respectively), is part of a 3.4-kb operon. In addition, we found a 2-kb monocistronic transcript. The half-life of each of these messages was approximately 13 min in denitrifying cells with a doubling time of around 2.5 h. When the culture was subjected to a low oxygen tension, we observed a transient expression of nirSlasting for about 30 min. The continued transcription of thenirS operon required the presence of nitrate or nitrite. This anaerobically manifested N-oxide response was maintained in nitrate sensor (NarX) and response regulator (NarL) knockout strains. Similar mRNA stability and transition kinetics were observed for the norCB operon, encoding the NO reductase complex, and the nosZ gene, encoding nitrous oxide reductase. Our results suggest that a nitrate- and nitrite-responsive regulatory circuit independent of NarXL is necessary for the activation of denitrification genes.

Denitrification within the genus Azospirillum and other associative bacteria

2001 ◽  
Vol 28 (9) ◽  
pp. 991 ◽  
Author(s):  
Karin Kloos ◽  
Alexander Mergel ◽  
Christopher Rösch ◽  
Hermann Bothe
Keyword(s):  
Nitrite Reductase ◽  
Plant Growth Promoting Rhizobacteria ◽  
Selective Advantage ◽  
Molecular Data ◽  
Associative Bacteria ◽  
Activity Measurements ◽  
Plant Growth Promoting ◽  
Cytochrome Cd1 ◽  
Polymerase Chain ◽  
Dissimilatory Nitrite Reductase

This paper originates from an address at the 8th International Symposium on Nitrogen Fixation with Non-Legumes, Sydney, NSW, December 2000 Different Azospirillumstrains and some other plant growth-promoting rhizobacteria (PGPR) were screened for the occurrence of genes coding for denitrification and nitrogenase reductase (nifH) using polymerase chain reaction (PCR)-based techniques. All PGPR examined were nitrogenase-positive. Azospirillum strains were remarkably dissimilar with respect to denitrification capabilities, in particular with respect to genes of the dissimilatory nitrite reductase. A. brasilense, A. lipoferum and A. halopraeferens strains possess a cytochrome cd1-containing nitrite reductase with low sequence similarities among them. A. irakense and A. doebereinerae have a Cu-containing nitrite reductase and A. amazonense is unable to denitrify. The molecular data were corroborated by activity measurements. The current results indicate that the inability to perform denitrification is unlikely a selective advantage for Azospirillum spp. and other associative bacteria for forming an association with plant roots.

scholarly journals Potentially Mobile Denitrification Genes Identified inAzospirillumsp. Strain TSH58

2018 ◽  
Vol 85 (2) ◽  
Author(s):  
Jeonghwan Jang ◽  
Yoriko Sakai ◽  
Keishi Senoo ◽  
Satoshi Ishii
Keyword(s):  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Nitrite Reductase ◽  
Rrna Gene ◽  
Content Type ◽  
Denitrification Gene ◽  
Nitrite Reductase Gene ◽  
Reductase Gene ◽  
Denitrification Genes ◽  
The 16S Rrna Gene

ABSTRACTDenitrification ability is sporadically distributed among diverse bacteria, archaea, and fungi. In addition, disagreement has been found between denitrification gene phylogenies and the 16S rRNA gene phylogeny. These facts have suggested potential occurrences of horizontal gene transfer (HGT) for the denitrification genes. However, evidence of HGT has not been clearly presented thus far. In this study, we identified the sequences and the localization of the nitrite reductase genes in the genomes of 41 denitrifyingAzospirillumsp. strains and searched for mobile genetic elements that contain denitrification genes. AllAzospirillumsp. strains examined in this study possessed multiple replicons (4 to 11 replicons), with their sizes ranging from 7 to 1,031 kbp. Among those, the nitrite reductase genenirKwas located on large replicons (549 to 941 kbp). Genome sequencing showed thatAzospirillumstrains that had similarnirKsequences also shared similarnir-norgene arrangements, especially between the TSH58, Sp7T, and Sp245 strains. In addition to the high similarity betweennir-norgene clusters among the threeAzospirillumstrains, a composite transposon structure was identified in the genome of strain TSH58, which contains thenir-norgene cluster and the novel IS6family insertion sequences (ISAz581and ISAz582). ThenirKgene within the composite transposon system was actively transcribed under denitrification-inducing conditions. Although not experimentally verified in this study, the composite transposon system containing thenir-norgene cluster could be transferred to other cells if it is moved to a prophage region and the phage becomes activated and released outside the cells. Taken together, strain TSH58 most likely acquired its denitrification ability by HGT from closely relatedAzospirillumsp. denitrifiers.IMPORTANCEThe evolutionary history of denitrification is complex. While the occurrence of horizontal gene transfer has been suggested for denitrification genes, most studies report circumstantial evidences, such as disagreement between denitrification gene phylogenies and the 16S rRNA gene phylogeny. Based on the comparative genome analyses ofAzospirillumsp. denitrifiers, we identified denitrification genes, includingnirKandnorCBQD, located on a mobile genetic element in the genome ofAzospirillumsp. strain TSH58. ThenirKwas actively transcribed under denitrification-inducing conditions. Since this gene was the sole nitrite reductase gene in strain TSH58, this strain most likely benefitted by acquiring denitrification genes via horizontal gene transfer. This finding will significantly advance our scientific knowledge regarding the ecology and evolution of denitrification.

Rahnella aquatilis, a nitrogen-fixing enteric bacterium associated with the rhizosphere of wheat and maize

1991 ◽  
Vol 37 (3) ◽  
pp. 195-203 ◽  
Author(s):  
Odile Berge ◽  
Thierry Heulin ◽  
Wafa Achouak ◽  
Claude Richard ◽  
Rene Bally ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Key Words ◽  
Dna Hybridization ◽  
Pure Culture ◽  
Tween 80 ◽  
Decarboxylase Activity ◽  
Enteric Bacterium ◽  
Diazotrophic Bacteria ◽  
Rahnella Aquatilis ◽  
First Time

In a study of dominant diazotrophic bacteria present in the rhizosphere of wheat and maize, 28 strains of Enterobacteriaceae were isolated. They were all Voges-Proskauer positive, motile at 28 °C but not at 37 °C, and they produced a Tween-80 esterase and did not exhibit decarboxylase activity. This fits well with the description of Rahnella aquatilis. The ability of these strains to reduce acetylene in pure culture and in association with their host plant and the DNA hybridization with a nifHDK probe are described. This is the first time that R. aquatilis is reported as a rhizosphere-associated bacterium and also a nitrogen fixer. Key words: Rahnella aquatilis, rhizosphere, wheat, maize, nitrogen fixation.

Distribution of denitrification and nitrogen fixation genes in Hyphomicrobium spp. and other budding bacteria

1998 ◽  
Vol 44 (2) ◽  
pp. 181-186 ◽  
Author(s):  
A. Fesefeldt ◽  
K. Kloos ◽  
H. Bothe ◽  
H. Lemmer ◽  
C.G. Gliesche
Keyword(s):  
Nitrogen Fixation ◽  
Budding Bacteria ◽  
Nitrogen Fixation Genes

How to assess chemical oxidation efficiency

2004 ◽  
Vol 49 (4) ◽  
pp. 1-6 ◽  
Author(s):  
G. Bertanza ◽  
R. Pedrazzani
Keyword(s):  
Reaction Mechanisms ◽  
Treatment Plant ◽  
Pilot Scale ◽  
Chemical Oxidation ◽  
Main Reaction ◽  
Additional Information ◽  
Activity Measurements ◽  
Real Wastewater ◽  
Oxidation Efficiency ◽  
Complex Organic

In this work, a real wastewater (deriving from the chemical-pharmaceutical field) was treated by means of H2O2/UV process under different conditions in a pilot-scale plant. Several methods were used in order to assess the oxidation efficiency and to understand the main reaction features. It was shown that non-conventional COD measurement (with a 75°C digestion of the sample) is helpful for understanding reaction mechanisms, when integrated with TOC and COD analyses and GC-MS determinations. For the biodegradability study, beside BOD (5 and 20 days) measurements, OUR and AUR tests provide additional information especially when wastewater is tested by taking the activated sludge from the treatment plant which should really be fed with it. Finally, dehydrogenase activity measurements can show the presence of complex organic matter, which may be degraded only by an acclimated biomass.

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