PMID- 31798571 OWN - NLM STAT- PubMed-not-MEDLINE LR - 20231104 IS - 1664-302X (Print) IS - 1664-302X (Electronic) IS - 1664-302X (Linking) VI - 10 DP - 2019 TI - Effect of Bacillus velezensis on Aeromonas veronii-Induced Intestinal Mucosal Barrier Function Damage and Inflammation in Crucian Carp (Carassius auratus). PG - 2663 LID - 10.3389/fmicb.2019.02663 [doi] LID - 2663 AB - Aeromonas veronii is an emerging aquatic pathogen causing hemorrhagic septicemia in humans and animals. Probiotic is an effective strategy for controlling enteric infections through reducing intestinal colonization by pathogens. Here we report that the consumption of Bacillus velezensis regulated the intestinal innate immune response and decreased the degree of intestinal inflammation damage caused by the A. veronii in Crucian carp. In this study, we isolated four strains of B. velezensis, named C-11, S-22, L-17 and S-14 from apparently healthy Crucian carp, which exerted a broad-spectrum antimicrobial activity inhibiting both Gram-positive and Gram-negative bacteria especially the fish pathogens. B. velezensis isolates showed typical Bacillus characteristics by endospore staining, physiological and biochemical test, enzyme activity analysis (amylase, protease, and lipase), and molecular identification. Here, Bacillus-containing dietary was orally administrated to Crucian carp for 8 weeks before A. veronii challenge. Immunological parameters and the expression of immune-related genes were measured at 2, 4, 6, 8, and 10 weeks post-administration. The results showed that B. velezensis was found to promote the increase in the phagocytic activities of peripheral blood leukocytes (PBLs) and head kidney leukocytes (HKLs), as well as the increase in interleukin 1beta (IL-1beta), IL-10 and tumor necrosis factor alpha (TNF-alpha) concentration of serum. Lysozyme levels (113.76 U/mL), ACP activity (25.32 U/mL), AKP activity (130.08 U/mL), and SOD activity (240.63 U/mL) were maximum (P < 0.05) in the B. velezensis C-11 treated group at 8 week. Our results showed that Crucian carp fed with the diet containing B. velezensis C-11 and S-22 developed a strong immune response with significantly higher (P < 0.05) levels of IgM in samples of serum, mucus of skin and intestine compared to B. velezensis L-17 and S-14 groups. Moreover, B. velezensis spores appeared to show no toxicity and damage in fish, which could inhabit the gut of Crucian carp. B. velezensis restrained up-regulation of pro-inflammation cytokines (IL-1beta, IFN-gamma, and TNF-alpha) mRNA levels in the intestine and head kidney at final stage of administration, and the expression of IL-10 was increased throughout the 10-week trial. A. veronii infection increased the population of inflammatory cells in the intestinal villi in the controls. In contrast, numerous goblet cells and few inflammatory cells infiltrated the mucosa in the B. velezensis groups after challenge with A. veronii. Compared with A. veronii group, B. velezensis could safeguard the integrity of intestinal villi. The highest post-challenge survival rate (75.0%) was recorded in B. velezensis C-11 group. The present data suggest that probiotic B. velezensis act as a potential gut-targeted therapy regimens to protecting fish from pathogenic bacteria infection. IMPORTANCE: In this work, four Bacillus velezensis strains isolated from apparently healthy Crucian carp, which exhibited a broad-spectrum antibacterial activity especially the fish pathogens. Administration of B. velezensis induced the enhancement of the intestinal innate immune response through reducing intestinal colonization by pathogens. The isolation and characterization would help better understand probiotic can be recognized as an alternative of antimicrobial drugs protecting human and animal health. CI - Copyright (c) 2019 Zhang, Kang, Zhan, Zhao, Jin, Chen, Zhang, Shen, Wang, Wang, Shan and Qian. FAU - Zhang, Dong-Xing AU - Zhang DX AD - College of Animal Science and Technology, Jilin Agricultural University, Changchun, China. FAU - Kang, Yuan-Huan AU - Kang YH AD - College of Animal Science and Technology, Jilin Agricultural University, Changchun, China. FAU - Zhan, Sheng AU - Zhan S AD - College of Animal Science and Technology, Jilin Agricultural University, Changchun, China. FAU - Zhao, Ze-Lin AU - Zhao ZL AD - College of Animal Science and Technology, Jilin Agricultural University, Changchun, China. FAU - Jin, Sheng-Nan AU - Jin SN AD - College of Animal Science and Technology, Jilin Agricultural University, Changchun, China. FAU - Chen, Chong AU - Chen C AD - College of Animal Science and Technology, Jilin Agricultural University, Changchun, China. FAU - Zhang, Lei AU - Zhang L AD - College of Animal Science and Technology, Jilin Agricultural University, Changchun, China. FAU - Shen, Jin-Yu AU - Shen JY AD - Agriculture Ministry Key Laboratory of Healthy Freshwater Aquaculture, Key Laboratory of Fish Health and Nutrition of Zhejiang Province, Zhejiang Institute of Freshwater Fisheries, Huzhou, China. FAU - Wang, Chun-Feng AU - Wang CF AD - College of Animal Science and Technology, Jilin Agricultural University, Changchun, China. FAU - Wang, Gui-Qin AU - Wang GQ AD - College of Animal Science and Technology, Jilin Agricultural University, Changchun, China. FAU - Shan, Xiao-Feng AU - Shan XF AD - College of Animal Science and Technology, Jilin Agricultural University, Changchun, China. FAU - Qian, Ai-Dong AU - Qian AD AD - College of Animal Science and Technology, Jilin Agricultural University, Changchun, China. LA - eng PT - Journal Article DEP - 20191115 PL - Switzerland TA - Front Microbiol JT - Frontiers in microbiology JID - 101548977 PMC - PMC6874145 OTO - NOTNLM OT - Aeromonas veronii OT - Bacillus velezensis OT - Crucian carp OT - antibacterial activity OT - disease resistance OT - immune-gene expression EDAT- 2019/12/05 06:00 MHDA- 2019/12/05 06:01 PMCR- 2019/11/15 CRDT- 2019/12/05 06:00 PHST- 2019/06/03 00:00 [received] PHST- 2019/11/01 00:00 [accepted] PHST- 2019/12/05 06:00 [entrez] PHST- 2019/12/05 06:00 [pubmed] PHST- 2019/12/05 06:01 [medline] PHST- 2019/11/15 00:00 [pmc-release] AID - 10.3389/fmicb.2019.02663 [doi] PST - epublish SO - Front Microbiol. 2019 Nov 15;10:2663. doi: 10.3389/fmicb.2019.02663. eCollection 2019.