This study investigated the effects of dietary Bacillus subtilis supplementation on growth performance, digestive enzyme activity, expression of antioxidant- and inflammation-related genes, and gut microbiota in juvenile GIFT (Oreochromis niloticus). The juvenile GIFT (total 540, initial body weight: 16.17 ± 1.32 g) were randomly divided into six groups and fed diets containing 0, 1 × 107, 1 × 108, 1 × 109, 1 × 1010, or 1 × 1011 CFU/kg B. subtilis for 60 days. Compared with the control group (0 CFU/kg B. subtilis), dietary B. subtilis significantly improved final body weight, weight gain rate, specific growth rate, and daily growth index and reduced feed conversion ratio (p < 0.05). Supplementation also significantly increased intestinal amylase, lipase, and trypsin activities (p < 0.05). In addition, the expression of several antioxidant-related genes was upregulated, whereas pro-inflammatory gene expression was generally downregulated in the intestine, liver, and head kidney. Gut microbiota analysis indicated that B. subtilis supplementation altered community composition, increased Firmicutes’ abundance, and reduced Proteobacteria abundance. Among all supplementation levels evaluated, the diet containing 1 × 109 CFU/kg B. subtilis produced the most favorable overall beneficial effects under the conditions of the present study.

This study conducted a 70-day feeding trial to evaluate the effects of dietary Lactobacillus plantarum supplementation (0, 0.1, 1.0, and 10.0 g/kg) in red claw crayfish (Cherax quadricarinatus). Growth performance, hepatopancreatic antioxidant-related parameters, and the expression of genes related to the Toll/Imd and JAK-STAT pathways were determined. Results showed that dietary L. plantarum supplementation significantly improved weight gain rate, specific growth rate, daily growth index, and feed efficiency, which were increased by 23.57%, 5.10%, 9.67%, and 7.90%, respectively, and reduced mortality rate by 60.00% compared with the control group (p < 0.05), enhanced the activities of glutathione peroxidase, catalase, superoxide dismutase and total antioxidant capacity, and reduced malondialdehyde levels in the hepatopancreas (p < 0.05). Furthermore, dietary L. plantarum supplementation was associated with the upregulated expression of key genes related to the Toll/Imd and JAK-STAT signaling pathways (p < 0.05). The expression levels of tumor necrosis factor-α, interleukin-1β, and transforming growth factor-β1 were also significantly increased (p < 0.05). Overall, these findings suggest that dietary L. plantarum supplementation improved growth performance and antioxidant-related and immune-related parameters in red claw crayfish, and that these effects were associated with the upregulated expression of genes involved in the Toll/Imd and JAK-STAT pathways. Among the tested treatments, 1.0 g/kg L. plantarum produced the most favorable overall response.

Intestinal oxidative imbalance, inflammatory activation, and microbial dysbiosis are increasingly recognized as major factors affecting the health status of intensively cultured largemouth bass (Micropterus salmoides). Chlorogenic acid (CGA) is a plant-derived polyphenolic compound that is well known for its antioxidant and anti-inflammatory properties. Although its inclusion as a dietary supplement in aquafeeds has garnered increasing interest, its effects on intestinal health in largemouth bass under normal rearing conditions remain largely unknown. Hence, the present investigation was designed to elucidate how incrementally elevated dietary CGA concentrations modulate oxidative capacity, inflammatory gene expression, mucosal histological features, and enteric microbiota structure in juvenile largemouth bass. In this study, largemouth bass were fed diets containing 0, 200, 400, or 600 mg/kg CGA for 70 days, and we evaluated intestinal antioxidant capacity, inflammation-related transcriptional responses, histomorphology, and gut microbiota were assessed. The results demonstrated that CGA supplementation significantly raised intestinal total antioxidant capacity as well as the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, while substantially decreasing malondialdehyde levels (p < 0.05). The transcription levels of cat, gsh-px, gst, sod, nrf2, and ucp2 were markedly upregulated, whereas keap1 expression was downregulated (p < 0.05). CGA supplementation also reduced the transcription levels of several proinflammatory genes, including il-1β, il-6, il-8, tnf-α, nf-κb, p50, map3k, jak2, as well as stat3, while significantly elevating il-10 expression, in the 200 and 400 mg/kg groups, tgf-β expression was also lowered (p < 0.05). Histological examination revealed that CGA supplementation influenced intestinal morphology in a dose-dependent manner; the most consistent improvements in villus length, villus width, and muscularis thickness occurred at the 400 mg/kg level, whereas the 600 mg/kg level showed weaker effects in several parameters compared with the control. Furthermore, 16S rRNA sequencing indicated that CGA altered microbial diversity, community structure, and predicted functional profiles in the intestine. In summary, dietary CGA supplementation was associated with enhanced intestinal antioxidant capacity, modified inflammation-related transcriptional responses, changes in intestinal morphology, and shifts in the gut microbial community of largemouth bass. Within the tested dose range, the 400 mg/kg group exhibited relatively favorable responses in several measured indicators under the present experimental conditions.

The objective of this research was to examine how varying dietary inclusion levels of Lactobacillus plantarum influence the muscle composition, hemolymph biochemical indices, lipid metabolism, and the mTOR signaling pathway in red claw crayfish (Cherax quadricarinatus). Four diets with 0 (CK), 0.10 (LG), 1.00 (MG), and 10.00 (HG) g/kg L. plantarum were formulated, with three replicates of 40 crayfish (average weight: 0.13 ± 0.01 g, average length: 0.58 ± 0.01 cm) in a 56-day trial. Results showed that no significant differences in muscle crude protein, crude lipid, ash, or moisture were observed between experimental and CK groups (p > 0.05), while the contents of multiple essential amino acids (e.g., arginine up to 6.05%, histidine up to 7.52%) and non-essential amino acids (e.g., aspartic acid up to 3.70%, glutamic acid up to 1.76%) were significantly elevated, and the content of muscle C18:0 (a saturated fatty acid) was notably reduced (p < 0.05), while total saturated fatty acids showed no significant variation among all groups (p > 0.05). Hemolymph alkaline phosphatase, transaminases, lactate dehydrogenase, and lysozyme activities, as well as glucose, total protein, and albumin levels, were significantly higher in experimental groups (p < 0.05). Lipid metabolism was upregulated, and the mTOR pathway was inhibited in experimental crayfish (p < 0.05). This study demonstrates that dietary L. plantarum enhances lipid metabolism in red claw crayfish, with 1.0 g/kg L. plantarum identified as the optimal supplementation level.

This study investigated the effects of dietary supplementation with the probiotic Enterococcus lactis on coho salmon (Oncorhynchus kisutch). A total of 360 juvenile fish, with an average initial weight of 130.75 ± 1.33g, were randomly assigned to four treatment groups, each with three replicates of 30 fish. The fish were fed for 70 days with diets containing four concentrations of E. lactis: 0 (control), 2×106, 4×108, and 8×1010 CFU/g. We evaluated growth performance, muscle composition, nutrient metabolism, digestive enzyme activity, immune function, intestinal histology, and microbiota structure. Our findings revealed that dietary supplementation with E. lactis significantly improved growth performance and feed utilization compared with the control group (P < 0.05), as indicated by increased weight gain rate (WGR) and specific growth rate (SGR) and reduced feed conversion ratio (FCR). In addition, E. lactis supplementation significantly enhanced muscle nutritional composition by increasing crude protein and crude lipid contents (P < 0.05), and promoted digestive capacity by increasing the activities of digestive enzymes, including lipase and α-amylase (P < 0.05). Moreover, E. lactis supplementation improved antioxidant and immune-related responses, as evidenced by increased activities of superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity (T-AOC), as well as the regulation of immune-related gene expression, including tlr3, tlr7, lzm, and tgf-β1，and other immune-associated genes (P < 0.05). Furthermore, E. lactis supplementation modulated intestinal microbial composition. The group receiving 4×10⁸ CFU/g showed the most pronounced effects across most measured parameters. These results indicate that dietary E. lactis supplementation, particularly at 4×10⁸ CFU/g, may improve growth performance and physiological status of juvenile coho salmon.

Probiotics are considered promising feed additives for enhancing fish health and production performance in aquaculture. This study evaluated the effects of dietary supplementation with Sporolactobacillus laevolacticus on growth performance, feed utilization, intestinal health, and physiological responses in juvenile coho salmon (Oncorhynchus kisutch). Fish were fed a control diet or diets supplemented with S. laevolacticus at 0.89 × 107, 0.90 × 109, or 0.87 × 1011 CFU/g for 10 weeks. Compared with the control, S. laevolacticus supplementation significantly increased final body weight, weight gain rate, specific growth rate, and protein efficiency ratio, while decreasing the feed conversion ratio (p < 0.05). It also significantly enhanced intestinal protease and α-amylase activities, improved serum biochemical and immune-related parameters, and promoted better intestinal morphology (p < 0.05). Additionally, S. laevolacticus supplementation led to elevated expression of antioxidant-related genes, reduced expression of pro-inflammatory genes, and altered gut microbial composition, characterized by a decrease in Proteobacteria and increases in Firmicutes and Lactobacillales. Among the tested dosages, 0.90 × 109 CFU/g produced the most consistent improvements in growth performance, digestive function, intestinal health, antioxidant and immune responses, and gut microbial composition, and was therefore identified as the optimal supplementation level. Collectively, dietary S. laevolacticus at 0.90 × 109 CFU/g improved growth performance and intestinal health in juvenile coho salmon, highlighting its potential as a probiotic candidate for coho salmon aquaculture.

The yellowfin seabream (Acanthopagrus latus) is an important aquaculture species, yet endocrine gene regulation during practical fasting and feeding schedules remains poorly understood. Here, we identified and characterized two duplicated proglucagon genes (Gcga and Gcgb) and examined tissue distribution of expression and transcriptional responses to feeding-related challenges. Sequence and phylogenetic analyses confirmed that Gcga and Gcgb cluster with teleost proglucagon paralogs and contain conserved peptide domains. Both genes were broadly expressed, with the strongest relative qRT-PCR signal detected in brain and fin, while other tissues (including intestine, gill, stomach, and liver) showed comparatively low but detectable expression. Because the liver is a central metabolic organ and displayed reproducible feeding-dependent regulation, we further quantified hepatic transcription under two paradigms. In a short-term starvation–refeeding trial, hepatic Gcga was significantly suppressed during fasting and rebounded after refeeding, whereas Gcgb showed a distinct, weaker response. In an acute peri-feeding assay, hepatic Gcga and Gcgb displayed rapid but differential regulation around meal time, and Gcgb expression differed between feeding and non-feeding groups. Together, these results support transcriptional divergence between the two proglucagon paralogs in nutritional regulation within a liver-focused metabolic-response model. Our findings provide baseline molecular information for A. latus and offer endocrine insights relevant to evaluating feeding strategies in aquaculture.

This review aims to summarize the current knowledge regarding the effects of various dietary additives on osmoregulation in aquaculture. It covers salt supplements, potassium supplements, myo-inositol supplements, metal ion supplements, and monosaccharides, emphasizing their importance in improving osmotic adjustment. The review provides an overview of the underlying mechanisms involved in osmoregulation and highlights the role of some specific dietary additives in promoting osmotic balance. Dietary salt and inorganic potassium directly provide ions for osmotic balance, while dietary metals, inositol, and monosaccharides can help mitigate the effects of osmotic stress and enhance the body's capacity for osmoregulation. Additionally, the addition of exogenous glucose not only provides energy required for osmoregulation but also acts as an osmolyte itself, contributing to osmoregulation. The review underscores the need for further research to better understand the interactions between dietary additives and osmoregulation in aquaculture. It also highlights the importance of considering species-specific requirements, optimal dosage levels, and the potential synergistic effects of combining multiple additives. Overall, carefully selected and properly administered dietary additives have the potential to improve osmoregulatory capacity, mitigate osmotic stress, and enhance the overall performance and welfare of cultured aquatic organisms. Future research should focus on elucidating the underlying mechanisms and optimizing the application of dietary additives to maximize their effectiveness in aquaculture systems.

This study investigated the effects of dietary Rhodotorula mucilaginosa supplementation with different concentrations (0.0 g/kg, 0.1 g/kg, 1.0 g/kg, 10.0 g/kg) on red claw crayfish (Cherax quadricarinatus). Four groups were established: control group (CK, 0.0 g/kg), low-dose group (HL, 0.1 g/kg), medium-dose group (HM, 1.0 g/kg), and high-dose group (HH, 10.0 g/kg). The feeding trial lasted for 56 days. The results showed that, compared with the control group, all supplementation groups exhibited significantly reduced feed conversion ratios (p < 0.05). The HM and HH groups demonstrated significant increases in body length growth rate, specific growth rate, weight gain rate, hepatosomatic index, and survival rate (p < 0.05). All supplemented groups showed significantly enhanced trypsin and lipase activities in intestines and trypsin activity in the hepatopancreas (p < 0.05). The HM and HH groups exhibited elevated α-amylase activity in the hepatopancreas (p < 0.05). Compared with the control group, marine red yeast supplementation reduced colonization of potential pathogens while increasing probiotic abundance, effectively improving intestinal microbiota structure. The HM group significantly improved intestinal villus length, width, and muscular thickness (p < 0.05). All supplemented groups showed considerable upregulation of hepatopancreatic genes related to immunity (heat shock protein 70, down syndrome cell adhesion molecule, crustacean antibacterial peptide, serine proteinase inhibitors, crustacean hyperglycemic hormone, anti-lipopolysaccharide factor, lysozyme, and alkaline phosphatase) and antioxidant defense (superoxide dismutase, glutathione peroxidase, glutathione, and catalase) (p < 0.05). These findings indicate that R. mucilaginosa can significantly enhance digestive enzyme activity, maintain intestinal health, improve antioxidant and immune-related gene expression, and promote growth performance in red claw crayfish, with the HM group (1.0 g/kg R. mucilaginosa) showing optimal promotion effects.

This study explored the impact of selenium yeast on the growth performance, body composition, digestive enzyme activity, antioxidant capacity, and lipid metabolism of juvenile GIFT tilapia (Oreochromis niloticus). The study involved juvenile tilapia with an initial average weight of 16.17 +/- 0.65 g, which were fed five different diets containing varying concentrations of selenium yeast (0 g/kg as the control group, and treatment groups receiving 0.1 g/kg, 0.2 g/kg, 0.3 g/kg, 0.4 g/kg, and 0.5 g/kg) over a period of 60 days. The measured dietary selenium concentrations were 0.05 +/- 0.01 mg/kg, 0.26 +/- 0.01 mg/kg, 0.44 +/- 0.01 mg/kg, 0.64 +/- 0.02 mg/kg, 0.87 +/- 0.03 mg/kg, and 1.03 +/- 0.03 mg/kg, respectively. The results indicated that dietary supplementation with selenium significantly enhanced the final body weight, weight gain rate, and specific growth rate compared to the control group (p < 0.05). Additionally, the hepatosomatic index, viscerosomatic index, and feed conversion ratio were significantly reduced (p < 0.05). Whole-body crude protein and selenium contents were significantly increased (p < 0.05) in all selenium-treated groups compared to the control. Moreover, the activities of trypsin, lipase, and alpha-amylase in the intestine were significantly enhanced by selenium supplementation (p < 0.05). At the molecular level, dietary selenium significantly upregulated the expression of catalase, glutathione peroxidase, and glutathione S-transferase in the liver and intestine (p < 0.05). Additionally, it significantly enhanced the expression of acetyl-CoA carboxylase alpha, carnitine palmitoyltransferase, fatty acid synthase, lipoprotein lipase, phosphoenolpyruvate carboxykinase, peroxisome proliferator-activated receptor alpha, beta, and gamma, as well as sterol regulatory element-binding protein 1 in the liver (p < 0.05). In summary, the inclusion of selenium in the diet markedly improved growth performance, digestive enzyme function, serum biochemical profiles, and the expression of genes involved in antioxidant defense systems, along with those regulating glucose and lipid metabolism in juvenile GIFT tilapia. Through quadratic polynomial regression analysis, the ideal dietary supplementation level of selenium for juvenile GIFT tilapia was estimated to range between 0.76 and 0.79 mg/kg.

This study investigated the effects of dietary supplementation with the probiotic Bacillus pumilus on coho salmon (Oncorhynchus kisutch). A total of 360 juvenile fish, with an average initial weight of 130.75 f 1.33 g, were randomly assigned to four treatment groups, each with three replicates of 30 fish. The fish were then fed for 70 days using formulated diets containing four concentrations of B. pumilus: 0 (control group), 2 x 106, 4 x 108, and 8 x 1010 CFU/g. We then evaluated growth, nutrient metabolism, immune-related serum biochemical markers, enzyme activity, gene expression, and muscle composition. Additionally, we assessed intestinal histology and microbiota composition. Our findings revealed that B. pumilus significantly improved growth, protein and fat metabolism, and immune function compared to the control group. It also had a positive effect on the structure and function of the intestinal microbiota. The group receiving 4 x 108 CFU/g showed the greatest improvements. Overall, B. pumilus appears to be a promising probiotic for enhancing the health and performance of coho salmon in aquaculture.

This study investigated the effects of dietary supplementation with varying levels (CK: 0.0 g/kg; RL: 0.1 g/kg; RM: 1.0 g/kg; RH: 10.0 g/kg) of Rhodotorula mucilaginosa on muscle composition, serum biochemical indicators, antioxidant capacity, lipid metabolism, and the mTOR signaling pathway in red claw crayfish (Cherax quadricarinatus). Results showed that, compared to CK, treatment groups had higher muscle crude protein, fat, leucine, histidine, arginine, and essential amino acids (p < 0.05), and lower saturated fatty acids (p < 0.05). Treatment groups also exhibited increased activities of alkaline phosphatase, acid phosphatase, superoxide dismutase, catalase, glutathione S-transferase, lysozyme, albumin, total protein, and antioxidant capacity (p < 0.05), with reduced activities of aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and triglycerides (p < 0.05). In the hepatopancreas, treatment groups showed significant downregulation of AMP-activated protein kinase α, β, and γ, and carnitine palmitoyltransferase 1 genes (p < 0.05). Conversely, genes involved in lipid anabolism (peroxisome proliferator-activated receptor γ, acetyl-CoA carboxylase, fatty acid synthase, sterol regulatory element-binding protein, protein kinase B, and mammalian target of rapamycin 1 and 2) were upregulated (p < 0.05). In conclusion, R. mucilaginosa supplementation affects muscle composition, lipid metabolism, and mTOR signaling. The optimal dose is 1.0 g/kg.

Mannan oligosaccharide (MOS), a prebiotic derived from yeast cell walls, has been shown to enhance growth performance and health status in various aquatic species. As an exogenous antigen adjuvant, MOS modulates T-cell-mediated immune responses, thereby improving immune function and suppressing excessive inflammatory reactions. This study aimed to evaluate the effects of dietary MOS supplementation on growth performance, serum biochemical parameters, muscle composition, digestive enzyme activity, antioxidant and immune status, and the mTOR signaling pathway in juvenile GIFT tilapia (Oreochromis niloticus). Juveniles (initial body weight: 16.17 ± 1.32 g) were randomly assigned to six treatment groups (three replicate tanks per group) and fed diets supplemented with MOS at 0, 0.2%, 0.4%, 0.6%, 0.8%, and 1% (equivalent to 0, 2, 4, 6, 8, and 10 g/kg of diet, respectively) for 60 days. Compared with the control group, fish fed MOS-supplemented diets exhibited significantly higher (p < 0.05) weight gain rates, specific growth rates, and protein efficiency ratios, along with a significantly lower (p < 0.05) feed conversion ratio. Serum albumin, high-density lipoprotein, and lysozyme levels were significantly increased (p < 0.05), whereas triglycerides, low-density lipoprotein, aspartate aminotransferase, and alanine aminotransferase levels were significantly decreased (p < 0.05). In the liver, head kidney, and spleen, the expression of pro-inflammatory genes (tumor necrosis factor α, interleukin 1β, interleukin 6, interleukin 8, and interferon γ) was significantly downregulated (p < 0.05), while the expression of antioxidant and protective genes (superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, nuclear factor erythroid 2-related factor 2, lysozyme, alkaline phosphatase, interleukin-10, transforming growth factor β, and heat shock protein 70) as well as mTOR signaling pathway-related genes (mammalian target of rapamycin, akt protein kinase B, phosphatidylinositol 3 kinase, and ribosomal protein S6 kinase polypeptide 1) was significantly upregulated (p < 0.05). Overall, MOS positively affects tilapia’s growth, health, and immunity, with 0.60% identified as the optimal dietary level based on growth performance.

Probiotics have become a widely recognized method for controlling diseases in aquaculture. The purpose of this study was to investigate the effects of spraying Bacillus circulans into the water on the growth, immune response, and gut microbiota of Litopenaeus vannamei, under the condition of feeding the same diet. In contrast to traditional feed supplementation approaches, the present work investigated the efficacy of B. circulans when introduced directly into aquaculture water systems as free-living suspensions. Four randomly chosen groups of 240 healthy shrimp (3.00 +/- 0.30 cm) were administered B. circulans at different concentrations (C: 0; L: 1.00 x 105 CFU/mL; M: 1.00 x 106 CFU/mL; H: 1.00 x 107 CFU/mL). The final body weight (FBW), weight gain rate (WGR), and specific growth rate (SGR) of juvenile Litopenaeus vannamei in the probiotic-treated groups significantly improved after 42 days of supplementation, especially in the 106 CFU/mL group. The digestive enzymes and antioxidant enzyme activity of the treatment groups also increased noticeably. Additionally, shrimp that received a B. circulans supplement displayed enhanced immunity, which was reflected by the upregulation of immunerelated genes (e.g., lectin, crustin). The groups sprayed with B. circulans exhibited greater intestinal microbial diversity and richness than the groups not sprayed with B. circulans, according to alpha diversity indices. According to beta diversity analysis, the bacterial communities in the B. circulans treatment groups differed from those in the non-sprayed groups but were similar to one another. After treatment with B. circulans, the relative abundance of potential pathogenic genera, such as Vibrio and Tenacibaculum, was significantly reduced. In summary, B. circulans regulated the intestinal microbiota of L. vannamei, enhanced digestion and immunity, and significantly boosted growth. Based on these results, we recommend the use of a B. circulans spray application at a concentration of 106 CFU/mL to optimize shrimp growth and health.

This study investigates the effect of dietary Lactobacillus plantarum supplementation on juvenile coho salmon (Oncorhynchus kisutch). Four groups of the juveniles (initial weight 103.87 ± 2.65 g) were fed for 10 weeks with four diets containing 0 (control diet), 105 (T1), 107 (T2), and 109 (T3) cfu/g of L. plantarum. The main results are as follows: Compared with the control diet, the final weight, specific growth rate (SGR), and weight gain rate (WGR) of the juveniles fed the T1, T2, and T3 diet significantly (p < 0.05) increased, while the feed coefficient ratio (FCR) expressed an opposite trend. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-PX) in the serum of the juveniles fed the T2 diet significantly (p < 0.05) increased, while the malondialdehyde (MDA) expressed an opposite trend. The expression of phosphatidylinositol 4,5-bisphosphate 3-kinase (pi3k), AKT-interacting protein (akt), mechanistic target of rapamycin kinase (mtor), glucose-6-phosphate dehydrogenase (g6pd), sod, cat, and gsh-px genes in the liver of the juveniles fed the T2 diet significantly (p < 0.05) increased. In conclusion, the T2 diet significantly improved the growth performance, antioxidant capacity, and upregulated key mTOR pathway genes in juvenile coho salmon.

This study investigated the effects of cadmium (Cd2+) exposure on the biochemical indexes, antioxidant responses, non-specific immune responses, inflammatory responses, anti-stress responses, and related gene expression levels of juvenile GIFT tilapia ( Oreochromis niloticus ). Four groups of juveniles were cultured for 30 days in four aquaculture waters with different levels of Cd2+ concentrations (0, 0.2, 0.4, and 0.6 mg/L). Key findings include: In comparison to the control group (0 mg/L Cd2+), cadmium stress significantly impacted the liver and serum biochemical indices of juvenile tilapia (p < 0.05). The activities of catalase (CAT), superoxide dismutase (SOD), and total antioxidant capacity (T-AOC) in the gills, liver, and serum were significantly decreased (p < 0.05) and the contents of malondialdehyde (MDA) showed the opposite trend. The expression levels of interleukin-10 (IL-10), sonic hedgehog (SHH), and cytochrome oxidase 1A (CYP1A) were significantly down-regulated (p < 0.05) and the expression levels of interleukin-1β (IL-1β), tumor necrosis factor α (TNFα), interferon γ (IFNγ), interleukin-6 (IL-6), interleukin-8 (IL-8), transforming growth factor β1 (TGF-β1), metallothionein (MT), and heat shock protein 70 (HSP70) in the liver were significantly up-regulated (p < 0.05). In conclusion, the concentration of cadmium in aquaculture water exceeded 0.2 mg/L, and the biochemical indexes, antioxidant responses, non-specific immune responses, inflammatory responses, and anti-stress responses of juvenile GIFT tilapia were markedly altered. These findings highlight that even sub-lethal Cd2+ concentrations (≥ 0.2 mg/L) pose substantial risks to the physiological health and survival of juvenile tilapia.

The objective of the present study was to evaluate the effects of gradient addition of Lactobacillus plantarum to feed on growth performance, digestive enzyme activities, antioxidant capacity, immune response, and intestinal health of red claw crayfish. The experiment comprised four distinct treatment groups: control group (CK, 0 gkg(-)(1)), low concentration group (LL, 0.10 gkg(-)(1)), medium concentration group (ML, 1.00 gkg(-)(1)), and high concentration group (HL, 10.00 gkg(-)(1)). Three biological replicates were established in each group, with each replicate containing 50 juvenile crayfish at the beginning of the experiment, with initial body weights ranging from 0.13 +/- 0.01 g. The experiment spanned 70 days. The experimental results showed that different concentrations of Lactobacillus plantarum significantly increased (p < 0.05) the weight gain rate, specific growth rate, length gain rate, hepatosomatic index, survival rate, and intestinal morphology in red claw crayfish. Additionally, the treatment significantly enhanced (p < 0.05) the activities of lipase, tryptase, and alpha-amylase in the intestine and hepatopancreas, and significantly up-regulated (p < 0.05) the expression of key genes in the hepatopancreas related to antioxidant defense, immunity, and stress response, including superoxide dismutase, glutathione peroxidase, glutathione, catalase, anti-lipopolysaccharide factor, crustacean hyperglycemic hormone, serine protease inhibitors, lysozyme, alkaline phosphatase, down syndrome cell adhesion molecule, antibacterial peptides, and heat shock protein 70. In conclusion, the addition of Lactobacillus plantarum to the feed of red claw crayfish significantly enhanced its growth performance, digestive enzyme activities, antioxidant capacity, and immune response capacity and positively affected its intestinal health. The optimum addition of Lactobacillus plantarum under this experiment was determined to be 1.00 gkg(-)(1) .

In aquaculture, the use of probiotics to improve growth, immunity, and stress resistance in crustaceans has gained increasing attention. This study examined the effects of incorporating different levels of Rhodotorula mucilaginosa (0.0, 0.1, 1.0, and 10.0 g/kg) into the diet on growth performance, antioxidant capacity (AOC), immune function, Toll/Imd, and JAK-STAT signaling pathways in red claw crayfish (Cherax quadricanatus). The investigation was conducted through a 56-day feeding trial. The main results are as follows: Compared with the control group (0.0 g/kg), different R. mucilaginosa levels significantly increased (p < 0.05) the specific growth rate (SGR) and weight gain rate (WGR) of red claw crayfish, significantly increased (p < 0.05) the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione S-transferase (GST), total AOC (T-AOC), and acid phosphatase (ACP) in hepatopancreas of red claw crayfish, and significantly upregulated (p < 0.05) the relative expression levels of tumor necrosis factor receptor-associated protein 6, akirin, immunodeficiency homolog, interferon regulatory factor 4, Toll-like receptor (TLR) 6, TLR 2, Janus kinase, signal transducer activator of transcription, tumor necrosis factor α, interleukin-1β, transforming growth factor-β1 genes in the hepatopancreas of red claw crayfish. In conclusion, R. mucilaginosa significantly enhanced red claw crayfish's growth, AOC, and immune function, and activated the Toll/Imd and JAK-STAT signaling pathways. In this experimental context, the ideal addition level of R. mucilaginosa is 1.0 g/kg.

The objective of this study was to evaluate the effects of dietary supplementation with different levels of Rhodotorula mucilaginosa (0.0 g/kg, 0.1 g/kg, 1.0 g/kg, and 10.0 g/kg) on resistance to Aeromonas veronii infection in red claw crayfish (Cherax quadricarinatus) (initial body weight of 0.13 ± 0.06 g). The investigation combined a 56-day feeding trial with a subsequent 7-day infection challenge to assess cumulative mortality, immune and antioxidant enzyme activities, and the relative expression of immune-related genes. During the A. veronii infection test, the cumulative mortalities for the 0.1 g/kg, 1.0 g/kg, and 10.0 g/kg groups were 44.44%, 38.89%, and 38.89%, respectively, all significantly lower (p < 0.05) than that of the control group (58.33%). Compared with the control group, after infection with A. veronii, the activities of acid phosphatase, alkaline phosphatase, catalase, and superoxide dismutase in the hepatopancreas and alkaline phosphatase, lysozyme in the hemolymph of red claw crayfish in the 1.0 g/kg group significantly increased (p < 0.05). The activities of aspartate aminotransferase and alanine aminotransferase in the hemolymph of red claw crayfish in the 1.0 g/kg group significantly decreased (p < 0.05). The relative expression levels of serine protease inhibitor, crustacean hyperglycemic hormone, anti-lipopolysaccharide factor, and superoxide dismutase genes in the hepatopancreas of red claw crayfish in the 1.0 g/kg group were significantly upregulated (p < 0.05). In conclusion, R. mucilaginosa could significantly improve the antibacterial ability of red claw crayfish against A. veronii. In this experimental context, the ideal addition level of R. mucilaginosa is determined to be 1.0 g/kg.

ABSTRACT The combination of aztreonam with ceftazidime/avibactam is considered a potential therapeutic approach for the treatment of infections caused by metallo-β-lactamase (MBL)-producing isolates. In this study, in vitro antibacterial activity of aztreonam with avibactam against 204 carbapenemase-producing Enterobacterales was determined by broth disk elution (BDE) method of two detection volumes (5- and 2-mL broth), with broth microdilution (BMD) method as a reference. For the BDE-5mL test, the categorical agreement (CA) of ATM+CZA -lo tube (aztreonam/ceftazidime/avibactam: 6/6/4 mg/L) was 99.5%, with 0.5% major error (ME) and 0% very major error (VME); the CA of 2ATM+CZA -lo tube (12/6/4 mg/L) was 100%, with no ME and VME. For the BDE-2mL test, the CA of ATM+2CZA -hi tube (15/10/4 mg/L) was 98.5%, with 0% ME and 37.5% VME; the CA of 2ATM+2CZA -hi tube (30/10/4 mg/L) was 97.1%, with 0% ME and 75% VME. The BDE-5 mL test is an economical and practical method for clinical microbiology laboratories to determine the antibacterial susceptibility of aztreonam with avibactam against Enterobacterales , especially the 2ATM+CZA -lo tube with a final concentration of 12/6/4 mg/L of aztreonam/ceftazidime/avibactam. IMPORTANCE Infections caused by metallo-β-lactamase (MBL)-producing Enterobacterales are increasingly reported worldwide, and it is a significant challenge for clinical infection treatment. MBLs are adept at hydrolyzing almost all traditional β-lactam antibiotics except aztreonam, and the enzyme activity cannot be inhibited by traditional or novel β-lactamase inhibitors. The good thing is that the combination of aztreonam with ceftazidime/avibactam has been proven to be one of the potential therapeutic approaches for treating infections related with MBL-producing isolates. Broth microdilution (BMD) method is recommended as a reference method for its accuracy, but it is too complex to perform in most routine laboratories. Finding a more convenient, practical, and accurate susceptibility testing method for aztreonam/avibactam in clinical microbiology laboratories is very necessary. Here, we evaluated the performance of broth disk elution (BDE) method for aztreonam in combination with ceftazidime/avibactam against Enterobacterales isolates, with BMD as a reference.