title: Immunostimulatory activities of specific bacterial secondary metabolite of Anoxybacillus flavithermus strain SX-4 on carp, Cyprinus carpio.
abstract: OBJECTIVE
  To determine the capacity of secondary metabolite of strain SX-4, to enhance the nonspecific immunity and survival of carp (Cyprinus carpio), and to identify the constituents that are responsible.
  
  
  RESULTS
  A thermophilic strain SX-4 that is able to produce immunostimulatory metabolite was isolated from sludge sample of hot spring and identified by comparison with 16S rRNA sequences (99% of homology) as Anoxybacillus flavithermus. Bioactivity-guided fractionation of methanol extract from its cell-free culture, one bacterial peptide with the capacity of improving the nonspecific immune responses and disease resistance (relative per cent survival = 66·67%) was obtained and the compound was characterized as cyclo-(L-Pro-Gly) by IR, ESI-MS, (1) H NMR and (13) C NMR spectroscopic analyses. After intraperitoneal administration of this peptide, selected innate immune parameters including phagocytic activity, superoxide anion production, serum lysozyme activity and serum SOD activity, along with immune-related genes expression (i.e. interleukin-1β and inducible nitric oxide synthase), in the blood were found to be significantly increased.
  
  
  CONCLUSIONS
  The bacterial peptide cyclo-(L-Pro-Gly) significantly enhances nonspecific immunity and survival of carp.
  
  
  CONCLUSIONS
  There is a possibility of using cyclo-(L-Pro-Gly) as a better natural immunostimulant, which could have a promising role in aquaculture to prevent diseases and disease outbreaks.
authors.affiliation: College of Life Sciences, Northwest University, Xi'an, China College of Animal Sciences and Technology, Northwest A&F University, Yangling, China.
authors.forename: J
authors.initials: J
authors.lastname: Liu
authors.forename: Y
authors.initials: Y
authors.lastname: Lei
authors.forename: F
authors.initials: F
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Yi
authors.forename: Y
authors.initials: Y
authors.lastname: Liu
authors.forename: G
authors.initials: G
authors.lastname: Wang
mesh_terms: D000276:Adjuvants, Immunologic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000818:Animals; D058677:Anoxybacillus / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001483:Base Sequence; D002347:Carps / Q000276:immunology*; D045482:Hot Springs / Q000382:microbiology; D007113:Immunity, Innate; D053583:Interleukin-1beta / Q000096:biosynthesis / Q000235:genetics; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D064210:Secondary Metabolism
chemical_list: D000276:Adjuvants, Immunologic; D053583:Interleukin-1beta; D010456:Peptides, Cyclic; C016325:cyclo(glycylprolyl)