title: Purification and characterization of a surfactin-like molecule produced by Bacillus sp. H2O-1 and its antagonistic effect against sulfate reducing bacteria.
abstract: BACKGROUND
  Bacillus sp. H2O-1, isolated from the connate water of a Brazilian reservoir, produces an antimicrobial substance (denoted as AMS H2O-1) that is active against sulfate reducing bacteria, which are the major bacterial group responsible for biogenic souring and biocorrosion in petroleum reservoirs. Thus, the use of AMS H2O-1 for sulfate reducing bacteria control in the petroleum industry is a promising alternative to chemical biocides. However, prior to the large-scale production of AMS H2O-1 for industrial applications, its chemical structure must be elucidated. This study also analyzed the changes in the wetting properties of different surfaces conditioned with AMS H2O-1 and demonstrated the effect of AMS H2O-1 on sulfate reducing bacteria cells.
  
  
  RESULTS
  A lipopeptide mixture from AMS H2O-1 was partially purified on a silica gel column and identified via mass spectrometry (ESI-MS). It comprises four major components that range in size from 1007 to 1049 Da. The lipid moiety contains linear and branched β-hydroxy fatty acids that range in length from C13 to C16. The peptide moiety contains seven amino acids identified as Glu-Leu-Leu-Val-Asp-Leu-Leu.Transmission electron microscopy revealed cell membrane alteration of sulfate reducing bacteria after AMS H2O-1 treatment at the minimum inhibitory concentration (5 μg/ml). Cytoplasmic electron dense inclusions were observed in treated cells but not in untreated cells. AMS H2O-1 enhanced the osmosis of sulfate reducing bacteria cells and caused the leakage of the intracellular contents. In addition, contact angle measurements indicated that different surfaces conditioned by AMS H2O-1 were less hydrophobic and more electron-donor than untreated surfaces.
  
  
  CONCLUSIONS
  AMS H2O-1 is a mixture of four surfactin-like homologues, and its biocidal activity and surfactant properties suggest that this compound may be a good candidate for sulfate reducing bacteria control. Thus, it is a potential alternative to the chemical biocides or surface coating agents currently used to prevent SRB growth in petroleum industries.
authors.affiliation: Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brasil.
authors.forename: Elisa
authors.initials: E
authors.lastname: Korenblum
authors.forename: Livia Vieira
authors.initials: LV
authors.lastname: de Araujo
authors.forename: Carolina Reis
authors.initials: CR
authors.lastname: Guimarães
authors.forename: Lauro M
authors.initials: LM
authors.lastname: de Souza
authors.forename: Guilherme
authors.initials: G
authors.lastname: Sassaki
authors.forename: Fernanda
authors.initials: F
authors.lastname: Abreu
authors.forename: Márcia
authors.initials: M
authors.lastname: Nitschke
authors.forename: Ulysses
authors.initials: U
authors.lastname: Lins
authors.forename: Denise Maria Guimarães
authors.initials: DM
authors.lastname: Freire
authors.forename: Eliana
authors.initials: E
authors.lastname: Barreto-Bergter
authors.forename: Lucy
authors.initials: L
authors.lastname: Seldin
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D001407:Bacillus / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D001938:Brazil; D002462:Cell Membrane / Q000648:ultrastructure; D002845:Chromatography; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D055666:Lipopeptides / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D013058:Mass Spectrometry; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017422:Sequence Analysis, DNA; D016999:Sulfur-Reducing Bacteria / Q000187:drug effects* / Q000648:ultrastructure; D013501:Surface-Active Agents / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D014871:Water Microbiology
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D055666:Lipopeptides; D013501:Surface-Active Agents