The effects of Bacillus subtilis on the immunity, mucosal tissue morphology, immune-related gene transcriptions, and intestinal microbiota in flounder (Paralichthys olivaceus) with two feeding methods: Continuous versus discontinuous feeding
Yingli Gao , Ruiming Tan , Zicheng Wang , Lu Qiang , Haijing Yao
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引用次数: 0
Abstract
Probiotics as dietary additives can improve weight gain, feed efficiency, and disease resistance in cultured fish. In this research, we evaluated and compared the effects of Bacillus subtilis on immunity, mucosal tissue morphology, immune-related gene transcriptions, and intestinal microbiota in flounder (Paralichthys olivaceus) by a 30-day feeding experiment based on a continuous feeding schedule (E1) and a discontinuous feeding schedule (E2). As a result, the use of B. subtilis exerted the best positive effects on survival rate, enzyme activity, mucosal tissue morphology, immune-related gene transcriptions, and intestinal microbiota in flounders. Alkaline phosphatase (AKP), lysozyme (LZM), and superoxide dismutase (SOD) activities in the liver of E2 were higher than those of E1 (P < 0.05). Furthermore, the villi length in the intestinal tract and the fold length in the stomach of E2 were also higher than in E1 (P < 0.05). The il-1 expression levels in the spleen were significantly increased in E2 (P < 0.05) compared to E1. We performed 16 S rRNA sequencing analysis to find that Bacillus in E1 (1.06%) and E2 (1.01%) had higher relative abundances than in E0 (0.053%) at the end of the experiments, indicating that short-term application of B. subtilis with the continuous or discontinuous feeding method can allow both the adaptation of the ecosystem to the presence of probiotics by the establishment of new species in the gut microbiota and the ability these new probiotic species to perform corresponding functions. No significant differences in the ability of probiotic establishment were observed between E1 and E2. Our findings provided a unique perspective to explore the mechanism of immune enhancement with probiotics and to screen the optimal administration strategy in aquaculture application for probiotic use. Together, these results point to some level of enhancement in immune status by continuous and discontinuous feeding after a short-term feeding period, which could be used as a prophylactic strategy for flounder health management.
期刊介绍：
The journal reports basic, comparative and clinical immunology as they pertain to the animal species designated here: livestock, poultry, and fish species that are major food animals and companion animals such as cats, dogs, horses and camels, and wildlife species that act as reservoirs for food, companion or human infectious diseases, or as models for human disease.
Rodent models of infectious diseases that are of importance in the animal species indicated above,when the disease requires a level of containment that is not readily available for larger animal experimentation (ABSL3), will be considered. Papers on rabbits, lizards, guinea pigs, badgers, armadillos, elephants, antelope, and buffalo will be reviewed if the research advances our fundamental understanding of immunology, or if they act as a reservoir of infectious disease for the primary animal species designated above, or for humans. Manuscripts employing other species will be reviewed if justified as fitting into the categories above.
The following topics are appropriate: biology of cells and mechanisms of the immune system, immunochemistry, immunodeficiencies, immunodiagnosis, immunogenetics, immunopathology, immunology of infectious disease and tumors, immunoprophylaxis including vaccine development and delivery, immunological aspects of pregnancy including passive immunity, autoimmuity, neuroimmunology, and transplanatation immunology. Manuscripts that describe new genes and development of tools such as monoclonal antibodies are also of interest when part of a larger biological study. Studies employing extracts or constituents (plant extracts, feed additives or microbiome) must be sufficiently defined to be reproduced in other laboratories and also provide evidence for possible mechanisms and not simply show an effect on the immune system.
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