title: Lactococcus lactis BFE920 activates the innate immune system of olive flounder (Paralichthys olivaceus), resulting in protection against Streptococcus iniae infection and enhancing feed efficiency and weight gain in large-scale field studies.
abstract: The protective effect of a food-grade lactic acid bacterium Lactococcus lactis BFE920 against disease of olive flounder (Paralichthys olivaceus) cultivated on a large scale was studied. Initially, antimicrobial activity of L. lactis against several fish pathogens was evaluated in vitro; the probiotic showed strong antibacterial activity against Streptococcus iniae, Streptococcus parauberis and Enterococcus viikkiensis, and moderate activity against Lactococcus garviae. When olive flounders were fed for two weeks with experimental diets containing varying concentrations of L. lactis (1 × 10(6), 5 × 10(6), 2.5 × 10(7) and 1.25 × 10(8) CFU/g feed), all the experimental feed groups showed 68-77% survival upon challenge with S. iniae. A field-scale feeding trial with L. lactis dietary supplement was conducted in a local fish farm (n = 12,000) for three months, and disease resistance, innate immune parameters and growth performance were evaluated. The average weight gain and feed efficiency were increased up to 6.8% and 8.5%, respectively. At the end of the feeding trial, the olive flounders were challenged with S. iniae. The L. lactis-fed group was protected from S. iniae challenge with a 66% survival rate. This disease protection is due to the flounder's innate immunity activated by the L. lactis administration: increased lysosomal activities and production of IL-12 and IFN-γ. These data clearly indicated that L. lactis BFE920 may be developed as a functional feed additive for protection against diseases, and for enhancement of feed efficiency and weight gain in olive flounder farming.
authors.affiliation: School of Life Science, Handong University, Pohang 791-708, Republic of Korea.
authors.forename: Daniel
authors.initials: D
authors.lastname: Kim
authors.forename: Bo Ram
authors.initials: BR
authors.lastname: Beck
authors.forename: Saet-Byeol
authors.initials: SB
authors.lastname: Heo
authors.forename: Jungjoon
authors.initials: J
authors.lastname: Kim
authors.forename: Hyun Duk
authors.initials: HD
authors.lastname: Kim
authors.forename: Sun-Min
authors.initials: SM
authors.lastname: Lee
authors.forename: Youngchan
authors.initials: Y
authors.lastname: Kim
authors.forename: So Young
authors.initials: SY
authors.lastname: Oh
authors.forename: Kyungro
authors.initials: K
authors.lastname: Lee
authors.forename: HyungKi
authors.initials: H
authors.lastname: Do
authors.forename: KwanHee
authors.initials: K
authors.lastname: Lee
authors.forename: Wilhelm H
authors.initials: WH
authors.lastname: Holzapfel
authors.forename: Seong Kyu
authors.initials: SK
authors.lastname: Song
mesh_terms: D000818:Animals; D017756:Aquaculture / Q000379:methods; D017931:DNA Primers / Q000235:genetics; D019587:Dietary Supplements; D005393:Fish Diseases / Q000276:immunology* / Q000517:prevention & control*; D005432:Flounder; D007113:Immunity, Innate / Q000187:drug effects / Q000276:immunology*; D013294:Lactococcus lactis; D009580:Nitroblue Tetrazolium; D019936:Probiotics / Q000494:pharmacology* / Q000627:therapeutic use; D060888:Real-Time Polymerase Chain Reaction; D013290:Streptococcal Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D015430:Weight Gain / Q000187:drug effects / Q000502:physiology
chemical_list: D017931:DNA Primers; D009580:Nitroblue Tetrazolium
keywords: IFN-γ; IL-12; Lactococcus lactis BFE920; Olive flounder; Probiotics