Huynh Truong-Giang, Shiu Ya-Li, Nguyen Thanh-Phuong, Truong Quoc-Phu, Chen Jiann-Chu, Liu Chun-Hung
Department of Aquaculture, National Pingtung University of Science and Technology, Pingtung 912, Taiwan, ROC; College of Aquaculture and Fisheries, CanTho University, CanTho, Viet Nam.
Department of Aquaculture, National Pingtung University of Science and Technology, Pingtung 912, Taiwan, ROC.
Fish Shellfish Immunol. 2017 May;64:367-382. doi: 10.1016/j.fsi.2017.03.035. Epub 2017 Mar 20.
Synbiotics, a conjunction between prebiotics and probiotics, have been used in aquaculture for over 10 years. However, the mechanisms of how synbiotics work as growth and immunity promoters are far from being unraveled. Here, we show that a prebiotic as part of a synbiotic is hydrolyzed to mono- or disaccharides as the sole carbon source with diverse mechanisms, thereby increasing biomass and colonization that is established by specific crosstalk between probiotic bacteria and the surface of intestinal epithelial cells of the host. Synbiotics may indirectly and directly promote the growth of aquatic animals through releasing extracellular bacterial enzymes and bioactive products from synbiotic metabolic processes. These compounds may activate precursors of digestive enzymes of the host and augment the nutritional absorptive ability that contributes to the efficacy of food utilization. In fish immune systems, synbiotics cause intestinal epithelial cells to secrete cytokines which modulate immune functional cells as of dendritic cells, T cells, and B cells, and induce the ability of lipopolysaccharides to trigger tumor necrosis factor-α and Toll-like receptor 2 gene transcription leading to increased respiratory burst activity, phagocytosis, and nitric oxide production. In shellfish, synbiotics stimulate the proliferation and degranulation of hemocytes of shrimp due to the presence of bacterial cell walls. Pathogen-associated molecular patterns are subsequently recognized and bound by specific pattern-recognition proteins, triggering melanization and phagocytosis processes.
合生元是益生元与益生菌的结合物，已在水产养殖中使用了10多年。然而，合生元作为生长和免疫促进剂的作用机制仍远未被阐明。在此，我们表明，作为合生元一部分的益生元会通过多种机制水解为单糖或双糖作为唯一碳源，从而增加生物量以及益生菌与宿主肠道上皮细胞表面之间通过特定串扰建立的定殖。合生元可能通过从合生元代谢过程中释放细胞外细菌酶和生物活性产物，间接和直接促进水生动物的生长。这些化合物可能会激活宿主消化酶的前体，并增强有助于食物利用效率的营养吸收能力。在鱼类免疫系统中，合生元会使肠道上皮细胞分泌细胞因子，这些细胞因子可调节树突状细胞、T细胞和B细胞等免疫功能细胞，并诱导脂多糖触发肿瘤坏死因子-α和Toll样受体2基因转录的能力，从而导致呼吸爆发活性、吞噬作用和一氧化氮产生增加。在贝类中，由于细菌细胞壁的存在，合生元会刺激虾血细胞的增殖和脱粒。随后，病原体相关分子模式会被特定的模式识别蛋白识别并结合，触发黑化和吞噬过程。
