title: Identification and characterization of Bacillus subtilis from grass carp (Ctenopharynodon idellus) for use as probiotic additives in aquatic feed.
abstract: Bacillus subtilis is widely used as probiotic species in aquaculture for water quality control, growth promoting, or immunity enhancing. The aim of this study is to find novel B. subtilis strains from fish as potential probiotics for aquaculture. Eleven B. subtilis isolates derived from the intestinal tract of grass carp were identified by gene sequencing and biochemical tests. These isolates were classified into 4 groups, and the representatives (GC-5, GC-6, GC-21 and GC-22) of each group were further investigated for antibiotic susceptibility, sporulation rate, biofilm formation, activity against pathogenic bacteria, resistance to stress conditions of intestinal tract (high percentage of bile and low pH) and high temperature, which are important for probiotics to be used as feed additives. Additionally, the adhesion properties of the 4 characterized strains were assessed using Caco-2 cell and gut mucus models. The results showed that the 4 strains differed in their capacities to adhere to intestinal epithelial cells and mucus. Furthermore, the strains GC-21 and GC-22 up-regulated the expression levels of IL-10 and TGF-β but down-regulated IL-1β, suggesting their potential anti-inflammatory abilities. Based on physiological properties of the 4 characterized B. subtilis strains, one or more strains may have potential to be used as probiotics in aquaculture.
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Guo
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Dan-Dan
authors.initials: DD
authors.lastname: Chen
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; Anhui Agricultural University, Hefei 230036, China.
authors.forename: Kai-Song
authors.initials: KS
authors.lastname: Peng
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Zheng-Wei
authors.initials: ZW
authors.lastname: Cui
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; Shanghai Ocean University, Shanghai 201306, China.
authors.forename: Xu-Jie
authors.initials: XJ
authors.lastname: Zhang
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
authors.forename: Shun
authors.initials: S
authors.lastname: Li
authors.affiliation: Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China. Electronic address: yzhang@ihb.ac.cn.
authors.forename: Yong-An
authors.initials: YA
authors.lastname: Zhang
mesh_terms: D000821:Animal Feed / Q000032:analysis / Q000382:microbiology*; D000818:Animals; D017756:Aquaculture; D001412:Bacillus subtilis / Q000302:isolation & purification*; D002347:Carps / Q000276:immunology / Q000382:microbiology* / Q000502:physiology*; D004032:Diet / Q000662:veterinary; D007113:Immunity, Innate; D007422:Intestines / Q000276:immunology / Q000382:microbiology; D019936:Probiotics / Q000302:isolation & purification*
keywords: Anti-inflammation; Bacillus subtilis; Grass carp; Probiotic; Stress condition resistance