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Mineralisation of the herbicide linuron by Variovorax sp. strain RA8 isolated from Japanese river sediment using an ecosystem model (microcosm)

Affiliation

  • 1 The Institute of Environmental Toxicology, Joso-shi, Ibaraki, Japan. [email protected]
  • PMID: 20603879
  • DOI: 10.1002/ps.1951

Mineralisation of the herbicide linuron by Variovorax sp. strain RA8 isolated from Japanese river sediment using an ecosystem model (microcosm)

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Author

Affiliation

  • 1 The Institute of Environmental Toxicology, Joso-shi, Ibaraki, Japan. [email protected]
  • PMID: 20603879
  • DOI: 10.1002/ps.1951

Abstract

Background: Linuron is a globally used phenylurea herbicide, and a large number of studies have been made on the microbial degradation of the herbicide. However, to date, the few bacteria able individually to mineralise linuron have been isolated only from European agricultural soils. An attempt was made to isolate linuron-mineralising bacteria from Japanese river sediment using a uniquely designed river ecosystem model (microcosm) treated with (14)C-ring-labelled linuron (approximately 1 mg L(-1)).

Results: A linuron-mineralising bacterium that inhabits river sediment was successfully isolated. The isolate belongs to the genera Variovorax and was designated as strain RA8. Strain RA8 gradually used linuron in basal salt medium (5.2 mg L(-1)) with slight growth. In 15 days, approximately 25% of (14)C-linuron was mineralised to (14)CO(2), with 3,4-dichloroaniline as an intermediate. Conversely, in 100-fold diluted R2A broth, strain RA8 rapidly mineralised (14)C-linuron (5.5 mg L(-1)) and more than 70% of the applied radioactivity was released as (14)CO(2) within 3 days, and a trace amount of 3,4-dichloroaniline was detected. Additionally, the isolate also degraded monolinuron, metobromuron and chlorobromuron, but not diuron, monuron or isoproturon.

Conclusion: Although strain RA8 can grow on linuron, some elements in the R2A broth seemed significantly to stimulate its growth and ability to degrade. The isolate strictly recognised the structural difference between N-methoxy-N-methyl and N,N-dimethyl substitution of various phenylurea herbicides.

Copyright (c) 2010 Society of Chemical Industry.

Although strain RA8 can grow on linuron, some elements in the R2A broth seemed significantly to stimulate its growth and ability to degrade. The isolate strictly recognised the structural difference between N-methoxy-N-methyl and N,N-dimethyl substitution of various phenylurea herbicides.

Secoviridae

VIRION

Non-enveloped, 25-30 nm in diameter, T=pseudo3 icosahedral capsid. The three jell rolls, which are characteristic of picornavirales capsid proteins (CP), can be present in one large CP with 3 jelly rolls domains, two CP (one large with two jelly rolls domains and one small a single domain), or three CP.

GENOME

Segmented, bipartite linear ssRNA(+) genome composed of RNA-1=6-8 kb and RNA-2=4-7 kb. Each genomic segment has a VPg linked to its 5′ end and a 3′ poly(A) tract.

GENE EXPRESSION

The virion RNA is infectious and serves as both the genome and mRNA.
RNA-1 and RNA-2 are translated into two polyproteins, which are then processed into functional proteins. RNA-1 encodes proteins necessary for replication, while RNA-2 encodes one or two capsid proteins and product(s) involved in cell-to-cell movement.

REPLICATION
  1. Virus penetrates into the cell.
  2. Uncoating, and release of the viral genomic RNA into the cytoplasm.
  3. Synthesis and proteolytic cleavage of the replicase polyprotein RNA-1.
  4. Replication occurs in viral factories made of membrane vesicles derived from the ER. A dsRNA genome is synthesized from the genomic ssRNA(+).
  5. The dsRNA genome is transcribed/replicated thereby providing viral mRNAs/new ssRNA(+) genomes.
  6. Assembly of new virus particles.
  7. Movement protein allows cell-to-cell movement.

DB LINKS Nucleotide DB: NCBI
Protein DB: UniProtKB
Virus DB: DPV TAXONOMY Group IV; ssRNA positive-strand viruses

Order:Picornavirales
Family:Secoviridae
Genus: Cheravirus
Sadwavirus
Sequivirus
Torradovirus
Waikavirus
Sub-family:Comovirinae
Genus: Comovirus
Fabavirus
Nepovirus ETYMOLOGY Seco: From the amalgamation of the former families sequiviridae and comoviridae TYPE SPECIES

TROPISM INTERACTIONS : –

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