title: Isolation and characterization of Rhizobium sp. strain YS-1r that degrades lignin in plant biomass.
abstract: OBJECTIVE
  The aim of this work was to isolate novel lignin-degrading organisms.
  
  
  RESULTS
  Several pure cultures of bacteria that degrade lignin were isolated from bacterial consortia developed from decaying biomass. Among the isolates, Rhizobium sp. strain YS-1r (closest relative of Rhizobium petrolearium strain SL-1) was explored for its lignin-degrading ability. Microcosm studies showed that strain YS-1r was able to degrade a variety of lignin monomers, dimers and also native lignin in switchgrass and alfalfa. The isolate demonstrated lignin peroxidase (LiP) activity when grown on alkali lignin, p-anisoin, switchgrass or alfalfa, and only negligible activity was measured in glucose-grown cells suggesting inducible nature of the LiP activity. Analysis of the strain YS-1r genome revealed the presence of a variety of genes that code for various lignin-oxidizing, H2O2-producing as well as polysaccharide-hydrolysing enzymes.
  
  
  CONCLUSIONS
  This study shows both the genomic and physiological capability of bacteria in the genus Rhizobium to metabolize lignin and lignin-like compounds. This is the first detailed report on the lignocellulose-degrading ability of a Rhizobium species and thus this study expands the role of alpha-proteobacteria in the degradation of lignin.
  
  
  CONCLUSIONS
  The organism's ability to degrade lignin is significant since Rhizobia are widespread in soil, water and plant rhizospheres and some fix atmospheric nitrogen and also have the ability to degrade aromatic hydrocarbons.
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Jackson
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Couger
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA.
authors.forename: M
authors.initials: M
authors.lastname: Prabhakaran
authors.affiliation: Department of Biosystems and Agricultural Engineering, Oklahoma State University, Stillwater, OK, USA.
authors.forename: K D
authors.initials: KD
authors.lastname: Ramachandriya
authors.affiliation: Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, USA.
authors.forename: P
authors.initials: P
authors.lastname: Canaan
authors.affiliation: Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA.
authors.forename: B Z
authors.initials: BZ
authors.lastname: Fathepure
mesh_terms: D018533:Biomass; D008031:Lignin / Q000378:metabolism*; D000455:Medicago sativa / Q000378:metabolism; D008897:Panicum / Q000378:metabolism; D012231:Rhizobium / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D008031:Lignin
keywords: Alfalfa; Rhizobium sp.; lignin biodegradation; lignin-oxidizing genes; switchgrass