title: Serratia entomophila bet gene induction and the impact of glycine betaine accumulation on desiccation tolerance.
abstract: OBJECTIVE
  The genes involved in choline transport and oxidation to glycine betaine in the biopesticidal bacterium Serratia entomophila were characterized, and the potential of osmoprotectants, coupled with increased NaCl concentrations, to improve the desiccation tolerance of this species was investigated.
  
  
  RESULTS
  Serratia entomophila carries sequences similar to the Escherichia coli betTIBA genes encoding a choline transporter and dehydrogenase, a betaine aldehyde dehydrogenase and a regulatory protein. Disruption of betA abolished the ability of Ser. entomophila to utilize choline as a carbon source. Quantitative reverse-transcriptase PCR analysis revealed that betA transcription was reduced compared to that of the upstream genes in the operon, and that NaCl and choline induced bet gene expression. Glycine betaine and choline increased the NaCl tolerance of Ser. entomophila, and osmotically preconditioned cultures survived better than control cultures following desiccation and immediately after application to agricultural soil.
  
  
  CONCLUSIONS
  Addition of glycine betaine and NaCl to growth medium can greatly enhance the desiccation survival of Ser. entomophila, and its initial survival in soil.
  
  
  CONCLUSIONS
  Serratia entomophila is sensitive to desiccation and does not persist under low soil moisture conditions. Techniques described here for enhancing the desiccation survival of Ser. entomophila can be used to improve formulations of this bacterium, and allow its application under a wider range of environmental conditions.
authors.affiliation: Innovative Farm Systems, AgResearch, Lincoln Research Centre, Christchurch, New Zealand.
authors.forename: T R
authors.initials: TR
authors.lastname: Sheen
authors.forename: M
authors.initials: M
authors.lastname: O'Callaghan
authors.forename: D J
authors.initials: DJ
authors.lastname: Smalley
authors.forename: C W
authors.initials: CW
authors.lastname: Ronson
authors.forename: M R H
authors.initials: MR
authors.lastname: Hurst
mesh_terms: D001483:Base Sequence; D001622:Betaine / Q000378:metabolism*; D050728:Betaine-Aldehyde Dehydrogenase / Q000096:biosynthesis / Q000235:genetics; D002794:Choline / Q000378:metabolism / Q000494:pharmacology; D050545:Choline Dehydrogenase / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D003890:Desiccation; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D017422:Sequence Analysis, DNA; D012705:Serratia / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D012988:Soil Microbiology; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D014157:Transcription Factors; D001622:Betaine; D012965:Sodium Chloride; D050545:Choline Dehydrogenase; D050728:Betaine-Aldehyde Dehydrogenase; D002794:Choline