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Mercury (Hg) is a global pollutant that affects the health of humans and ecosystems. Selenium (Se) is an essential trace element for many organisms including humans. Bacillus subtilis is one of the main probiotics used in aquaculture, and has a certain adsorption effect on heavy metals. The interaction between Hg and Se was rigorously studied, especially due to the observation of the protective effect of Se on Hg toxicity. The objective of this study was to research the effects of Hg, Se, and B. subtilis on inflammation and intestinal microbes in common carp. The common carp was exposed to Hg (0.03 mg/L), and 10 5  cfu/g Se-rich B. subtilis was added to the feed. After 30 days of feeding, samples were taken to evaluate the growth performance, serological response, inflammatory response, and intestinal microbial changes. In this study, when fish were exposed to Hg, the growth performance of the Se-rich B. subtilis plus 0.03 mg/L Hg fish group was lower than that of the control group and higher than 0.03 mg/L Hg; The levels of serum immunoglobulin M (IgM) and lysozyme (LZM) decreased, but after supplementation with Se-rich B. subtilis, the levels of LZM and IgM increased; Hg treatment significantly upregulated the mRNA expression of interleukin-1β (IL-1β), interleukin-8 (IL-8), tumor necrosis factor-α (TNF-α), and nuclear factor-kB (NF-κB P65), but downregulated the mRNA expression of interleukin-10 (IL-10), transforming growth factor-β (TGF-β) and NF-kappa-B inhibitor alpha (IkBα). However, compared with the Hg group, the Se-rich B. subtilis plus Hg group can significantly increase the mRNA expression levels of IL-1β, IL-8, TNF-α, and NF-κB P65, but reduce the regulation of IL-10, TGF-β, and IkBα expression. Through the analysis of the microbiological, we found that the Hg group was mainly composed of Aeromonas sobria and Aeromonas hydrophila. However, in the Se-rich B. subtilis treatment group, we found that Aeromonas sobria was significantly less than the Hg group. Se-rich B. subtilis improves Hg-induced intestinal microbial changes, alleviates the abundance of Aeromonas, and alleviates the inflammation of the fish. The results of this study show that Se-rich B. subtilis dietary supplements can effectively protect common carp against Hg toxicity., (© 2022. The Author(s), under exclusive licence to Springer Nature B.V.)

Lead (Pb), a heavy metal and an environmental stressor, may affect many physiological processes, including the serum index and the immune response. The aim of this study was to explore the toxic effects of Pb on the serum index and the immune response of Carassius auratus gibelio (C. gibelio) fed 0, 120, or 240 mg/kg Pb, and 10 9  cfu/g Bacillus subtilis (B. subtilis). After 15 and 30 days of dietary exposure, the serum indices and the immune responses of the fish were assessed. Dietary Pb exposure significantly affected various components of the serum index, including calcium, magnesium, glucose, cholesterol, total protein, glutamic-pyruvic transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH). However, sIgA activity in the gut increased significantly following B. subtilis supplementation. Notable changes were also observed in the expression levels of immune-related genes, including HSP70, IgM, HSP90, IL-1β, IL-6, and TNF-α. B. subtilis supplementation effectively attenuated the effects of dietary Pb exposure.

Lead (Pb) is one of the most ubiquitous and toxic elements in the aquatic environment. Bacillus subtilis (B. subtilis) is a widely used probiotic in aquaculture. The aim of this study was to explore the toxic effects on bioaccumulation, hematological parameters, and antioxidant responses of Carassius auratus gibelio (C. gibelio) exposed to dietary lead at 0, 120, and 240 mg/kg and/or B. subtilis at 10 9  cfu/g. At 15 and 30 days, the fish were sampled and bioaccumulation, hematological parameters, and antioxidant responses were assessed. The result showed that B. subtilis administration can provide a significant protection against lead toxicity by reducing lead bioaccumulation in tissues, increasing the antioxidant enzymes activity, recovering δ-aminolevulinic acid dehydratase activity and optimizing the hematological parameters. Our results suggested that administration of B. subtilis (109 cfu/g) has the potential to combat dietary lead toxicity in C. gibelio.

Lead (Pb) poisoning in humans and fish represents a significant global problem. Bacillus subtilis (B. subtilis) is a widely used probiotic in aquaculture. Carassius auratus gibelio (C. gibelio) is one of the most important aquaculture species with great commercial value. The objective of this study was to evaluate the potential of B. subtilis in ameliorating lead-induced toxicity in C. gibelio. The fish were exposed for 60 days to waterborne Pb at 0, 0.05, 0.5 and 1 mg/L and/or dietary B. subtilis at 10 9 cfu/g. After 30 and 60 days, the fish were sampled and bioaccumulation, antioxidant activity and immune responses were assessed. The results revealed that B. subtilis confers significant protective effects against lead toxicity by preventing alterations in the levels of bioaccumulation, superoxide dismutase, catalase and glutathione. B. subtilis also assists in the recovery of blood δ-aminolevulinic acid dehydratase, lysozyme, and IgM levels while regulating the expression of immune-related genes including IL-10, lysozyme, TNF-α, IgM and Hsp70 after 60 days of lead exposure. Our results suggest that administration of B. subtilis (10 9 cfu/g) has the potential to combat lead toxicity in C. gibelio., (Copyright © 2018. Published by Elsevier Inc.)

Salinity and alkalinity are important indicators of the aquatic environment, and saline-alkali stress has negative effects on aquatic organisms. Dietary supplementation with probiotics can improve the overall health and productivity of aquatic animals. Bacillus subtilis is a widely used probiotic in aquaculture. A total of 240 Carassius auratus gibelio (13.85 ± 0.15 g) were assigned to four groups. This experiment used a completely randomized design with three replicates and a 2 × 2 factorial scheme, with two saline-alkali concentrations (0 g/L NaCl + 0 g/L NaHCO3 and 5 g/L NaCl + 2.52 g/L NaHCO3) and two diets (control and supplemented with 108 CFU/g B. subtilis). After 12, 24, 48, 72, and 96 h of saline-alkali exposure, fish blood samples were collected and serum levels of immunoglobulin M, alkaline phosphatase, and acid phosphatase were measured. Gills and kidneys were sampled to analyze superoxide dismutase activity, catalase activity, malondialdehyde content, and histopathological alterations. The results suggested that a B. subtilis-supplemented diet may enhance immunity, improve antioxidant ability, and reduce tissue damage in C. gibelio exposed to saline-alkali stress. [ABSTRACT FROM AUTHOR]

The present study evaluated the adjuvant effects of Bacillus subtilis (B. subtilis) spores on the immune response induced by an SVCV‐M protein, which was equivalent to a subunit vaccine in German mirror carp (Cyprirnus Carpio Songpa Linnaeus Mirror). The following results were observed: in vitro, there were no toxic effects of B. subtilis spores and SVCV‐M protein on the viability of epithelioma papulosum cyprini (EPC) cells. In addition, B. subtilis spores can significantly reduce the oxidative damage of the spring viraemia of carp virus (SVCV) on EPC cells, but protein‐M had no significant effects on the oxidative damage of EPC cells. In vivo, higher levels of specific IgM could be detected in the protein‐M+B. subtilis spores group, compared with that in PBS, B. subtilis spores and Protein‐M groups. Immune‐related indexes including the activities of LZM and AKP and the content of C3 and C4 in the protein‐M+B. subtilis spores group were strongly upregulated. Immune‐related genes had the same trend as the immune‐related indexes. Furthermore, the antioxidant capacity of the protein‐M+B. subtilis spores group was also better than that of PBS, B. subtilis spores and Protein‐M groups. Finally, the highest survival rate (59.69%) was observed in the protein‐M+B. subtilis spores group, while the survival rate was 8.89% in protein‐M group, and 0% in the PBS and B. subtilis spores groups. This study suggests B. subtilis spores as an adjuvant that can enhance the protection efficacy of the SVCV subunit vaccine (SVCV‐M protein) in common carp. [ABSTRACT FROM AUTHOR]

Bacillus can not only improve the ecological environment of aquaculture water, but also improve the immunity of aquaculture animals, inhibit the reproduction of pathogenic microorganisms and reduce the incidence of disease. The present study represented the effect of different combinations of Bacillus on immunity and antioxidant activities in common carp. A total of 240 fish were randomly divided into four groups: control group (basal diet), experimental group I (add B. subtilis), experimental group II (add B. subtilis and B. licheniformis), and experimental group III ( B. subtilis, B. licheniformis, and B. cereus). Compared with the control group, the carp in experimental group II displayed a significantly elevated phagocytic percentage (up to a 20.2% increase; P < 0.05), phagocytic index (up to a 41.5% increase; P < 0.05), serum immunoglobulin M (up to a 26.1% increase; P < 0.05), serum lysozyme activity (up to a 21.9% increase; P < 0.05), intestinal mucosal secretory immunoglobulin A content (up to a 53.1% increase; P < 0.05), and peripheral blood lymphocyte proliferation ratio (up to a 32.8% increase; P < 0.05). Further analysis of liver antioxidants showed that, compared with the control group, carp in experimental group II displayed elevated superoxide dismutase (69.4%; P < 0.05), glutathione peroxidase (25.4%; P < 0.05), catalase (76.4%; P < 0.05), total antioxidant (41.1%; P < 0.05), maleic dialdehyde (28.9%; P < 0.05), and glutathione (35.6%; P < 0.05) activities. There was no significant difference between the experimental group I and the experimental group III ( P > 0.05). Our results indicated that dietary Bacillus enhanced the performance of the common carp immune response and that a mixture of strains elevated the antioxidant ability. [ABSTRACT FROM AUTHOR]

In this study, a total of 420 healthy crucian carp (9.77 ± 0.04 g) were randomly divided into CK, B·S , XOS and B·S + XOS group, and cultured for 8 weeks. Results showed that the dietary Bacillus subtilis (B. subtilis) and xylo-oligosaccharides (XOS) can significantly increased the final weight, weight gain, specific growth rate, feed efficiency, protein efficiency and survival rate of crucian carp. Dietary B. subtilis and XOS can significantly increased the activities of catalase, glutathione, superoxide dismutase and total antioxidant capacity, significantly decreased the contents of malondialdehyde, and significantly increased the activities of alkaline phosphatase, acid phosphatase, lysozyme and the contents of complement component 3,4 and immunoglobulin M in crucian carp serum. In addition, compared with CK group, the expression levels of TGF-β and IL-10 in B·S , XOS and B·S + XOS group were significantly increased, and the expression levels of TNF-α, HSP90, IL-1β, TLR4 and MyD88 were significantly decreased. Supplementation of B. subtilis and XOS can also improve the intestinal tissue morphology of crucian carp. After injection of 1 × 107 CFU/mL Aeromonas hydrophila (A. hydrophila), compared with CK group, the survival rates of the B·S group, the XOS group and the B·S + XOS group were increased by 13.98%, 10.56% and 30.74%, respectively. These results show that dietary B. subtilis and XOS can significantly improve the growth performance, antioxidant capacity, immunity and resistance to A. hydrophila of crucian carp, and the combined effect is better than that of single addition. The graphical abstract of CBC 109296 (Title: Boosted growth performance, immunity, antioxidant capacity and disease resistance of crucian carp (Carassius auratus) by single or in combination dietary Bacillus subtilis and xylo-oligosaccharides). [Display omitted] • Dietary B. subtilis and XOS can improve the growth performance, immunity and antioxidant capacity of crucian carp. • Supplementation of B. subtilis and XOS in feed can significantly improve the intestinal tissue morphology of crucian carp. • Dietary B. subtilis and XOS can significantly improve the resistance of crucian carp to Aeromonas hydrophila infection. [ABSTRACT FROM AUTHOR]

Mercury (Hg) poisoning in humans and fish represents a significant global problem. Hg is one of the most dangerous threats to the aquatic ecosystem due to its high toxicity. Mercury has a high oxidative stress-inducing potential, and can compounds exert toxic effects by interacting with many important enzymes involved in the regulation of antioxidants. Selenium (Se) supplementation can reactivate the mercury-inhibited enzymes viability. The probiotic Bacillus subtilis is widely used in aquaculture, and it has a certain adsorption effect on heavy metals. The interactions between Hg and Se have been rigorously investigated, particularly due to the observed protective effects of Se against Hg toxicity. The objective of this study was to evaluate whether Se-rich B. subtilis ameliorated Hg-induced toxicity in C. carpio var. specularis. Fish were exposed to waterborne Hg (0.03 mg/L) and fed a diet supplemented with 105 cfu/g Se-rich B. subtilis for 30 days. Fish were sampled, antioxidant activity, and Intestinal damage repair were assessed. Our results indicated that Se-rich B. subtilis protected the Intestinal from Hg-induced morphological changes. Hg treatment significantly decreased the activity levels of SOD, CAT and GSH-PX while increasing the activity levels of MDA, GST, and GSH. Hg treatment also upregulated the mRNA expression of Nrf2 , CAT , GSH-PX and HO-1 , and reduced expression of keap1. Se-rich B. subtilis had a significant protective effect against Hg-induced oxidative stress. Unlabelled Image • Dietary selenium-rich Bacillus subtilis significantly alleviates mercury induced oxidative stress. • Selenium-rich Bacillus subtilis protected the intestinal from the histological damage induced by Hg exposure. [ABSTRACT FROM AUTHOR]