Search

Abstract We aimed to differentiate and evaluate the clinical imaging features of pulmonary cryptococcosis with different therapeutic responses. The clinical imaging data of 70 patients with PC (complete response PC 37 cases and incomplete response PC 33 cases) were collected and compared to determine the independent risk factors for different therapeutic responses, and their diagnostic performances were verified by receiver operating characteristic curve analysis. Compared with complete response PC, incomplete response PC was more common with immunosuppression (10.8% vs. 45.5%, P = 0.001), intermediate progress (8.1% vs. 39.4%, P = 0.002), bilateral distribution (21.6% vs. 78.8%, P

Abstract Background Evidence has accumulated to demonstrate that intestinal microbiome can inhibit viral infection. However, our knowledge of the signaling pathways and identity of specific commensal microbes that mediate the antiviral response is limited. Zebrafish have emerged as a powerful animal model for study of vertebrate-microbiota interactions. Here, a rhabdoviral infection model in zebrafish allows us to investigate the modes of action of microbiome-mediated antiviral effect. Results We observed that oral antibiotics-treated and germ-free zebrafish exhibited greater spring viremia of carp virus (SVCV) infection. Mechanistically, depletion of the intestinal microbiome alters TLR2-Myd88 signaling and blunts neutrophil response and type I interferon (IFN) antiviral innate immunity. Through 16S rRNA sequencing of the intestinal contents from control and antibiotic(s)-treated fish, we identified a single commensal bacterial species, Cetobacterium somerae, that can restore the TLR2- and neutrophil-dependent type I IFN response to restrict SVCV infection in gnotobiotic zebrafish. Furthermore, we found that C. somerae exopolysaccharides (CsEPS) was the effector molecule that engaged TLR2 to mediate the type I IFN-dependent antiviral function. Conclusions Together, our results suggest a conserved role of intestinal microbiome in regulating type I IFN antiviral response among vertebrates and reveal that the intestinal microbiome inhibits viral infection through a CsEPS-TLR2-type I IFN signaling axis in zebrafish. Video Abstract

This study aimed to investigate the effects of solid-state fermentation products of yeast (SFPY) on liver and intestinal health and disease resistance of common carp (Cyprinus carpio). A total of 200 common carp with an initial average weight of 2.55 ± 0.004 g were divided into 5 groups (4 replications per group and 10 fish per replication), and were fed with one of five diets, including a control diet and 4 diets supplemented with 2‰ (Y2), 3‰ (Y3), 4‰ (Y4), or 5‰ (Y5) SFPY, respectively, for 8 weeks. Results indicated that, the addition of SFPY to the diet of common carp did not affect the growth performance or survival rate of fish (P = 0.253). Interestingly, with the addition of SFPY, the triacylglycerol (TAG) content of the liver presented a linear decreasing tendency (P = 0.004), with significantly decreased in Y4 and Y5 groups (P = 0.035) compared with control. Serum lipopolysaccharide (LPS) content and diamine oxidase (DAO) activity presented a negative linear relationship with the addition of SFPY (P = 0.015, P = 0.030), while serum lipopolysaccharide binding protein (LBP) content first decreased and then increased (P

Microbial oil, as an alternative to fish oil, animal and vegetable oils in aquafeeds, have a great potential to fulfil the high demand for lipid sources in the fast-growing aquaculture. However, their use as a feed ingredient in aquaculture is not common. For that, Rhodotorula toruloides (51.90 % lipid) was used to replace 0.00 % (control), 9.38 % (RT3), 18.75 % (RT6), 37.50 % (RT9), and 56.25 % (RT18) of the lard and soybean oils commonly used in aquaculture in the diet of zebrafish. After 6 weeks of feeding, compared with the control group, (1) the FBW and WGR were significantly increased (p

The application of commensal probiotic bacteria is one of the preferable green feed additives for antibiotic substitution in aquaculture, while the application methods and detailed action mechanisms of commensal bacteria isolated from aquatic animals are not consistent with normal mammalian-derived probiotics. The purpose of this study was to evaluate the effects of solid-state fermentation product of autochthonous Bacillus velezensis T23 on improving hepatic steatosis, liver antioxidation capacity, gut injury and gut microbiota profile of genetically improved farmed tilapia (GIFT, Oreochromis niloticus). The T23 probiotic was added to the basal diet at a level of 0.00, 0.05, 0.1, 0.2 and 0.3 g/kg to develop five experimental diets, respectively. After 4 weeks of the feeding trial, the results showed that T23 supplementation notably reduced the hepatocytes vacuolization and the content of liver TAGs by downregulated the mRNA expression of the lipogenesis gene (fas), while upregulated the mRNA expression of lipid degradation genes (cpt1 and pparα) (p

Abstract Background Aquaculture plays an important role in global protein supplies and food security. The ban on antibiotics as feed additive proposes urgent need to develop alternatives. Gut microbiota plays important roles in the metabolism and immunity of fish and has the potential to give rise to novel solutions for challenges confronted by fish culture. However, our understanding of fish gut microbiome is still lacking. Results We identified 575,856 non-redundant genes by metagenomic sequencing of the intestinal content samples of grass carp. Taxonomic and functional annotation of the gene catalogue revealed specificity of the gut microbiome of grass carp compared with mammals. Co-occurrence analysis indicated exclusive relations between the genera belonging to Proteobacteria and Fusobacteria/Firmicutes/Bacteroidetes, suggesting two independent ecological groups of the microbiota. The association pattern of Proteobacteria with the gene expression modules of fish gut and the liver was consistently opposite to that of Fusobacteria, Firmicutes, and Bacteroidetes, implying differential functionality of Proteobacteria and Fusobacteria/Firmicutes/Bacteroidetes. Therefore, the two ecological groups were considered as two functional groups, i.e., Functional Group 1: Proteobacteria and Functional Group 2: Fusobacteria/Firmicutes/Bacteroidetes. Further analysis revealed that the two functional groups differ in genetic capacity for carbohydrate utilization, virulence factors, and antibiotic resistance. Finally, we proposed that the ratio of “Functional Group 2/Functional Group 1” can be used as a biomarker that efficiently reflects the structural and functional characteristics of the microbiota of grass carp. Conclusions The gene catalogue is an important resource for investigating the gut microbiome of grass carp. Multi-omics analysis provides insights into functional implications of the main phyla that comprise the fish microbiota and shed lights on targets for microbiota regulation. Video Abstract

This study investigated the effects of Lactobacillus rhamnosus fermentation products added to feed on common carp (Cyprinus carpio) on growth, gut and liver health, and gut microbiota. Common carp with an average weight of 1.95±0.4 g were fed five experimental diets: normal diet (normal) and normal diet supplemented with Lactobacillus rhamnosus fermentation products (abbreviation: 0.2% GCC-3, 0.3% GCC-3, 0.4% GCC-3 and 0.5% GCC-3, respectively) for 8 weeks. The results showed that the GCC-3 fermentation product did not affect the growth phenotype of common carp. The diet supplemented with 0.3% GCC-3 significantly reduced the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels of common carp compared to the control group. Diets with GCC-3 fermentation products significantly reduced liver triacylglycerol (TAG) levels. Diets supplemented with 0.3% GCC-3 fermentation products significantly downregulated the expression of liver liposynthesis gene (fas) and significantly upregulated the expression of liver lipolysis gene (cpt1). Diets supplemented with GCC-3 significantly reduced the serum lipopolysaccharide (LPS) levels of common carp compared to the control group. In addition, dietary supplementation with 0.3% GCC-3, 0.4% GCC-3, or 0.5% GCC-3 all increased the abundance of Cetobacterium and decreased the abundance of Acinetobacter. In summary, dietary supplementation with 0.3% GCC-3, 0.4% GCC-3, and 0.5% GCC-3 reduced liver lipid deposition, and improved gut microbiota homeostasis of common carp. The best positive effect was observed in common carp fed a 0.3% GCC-3 supplemental diet.

Abstract Lactobacillus rhamnosus GG (LGG), the well‐characterized human‐derived probiotic strain, possesses excellent properties in the maintenance of intestinal homeostasis, immunoregulation and defense against gastrointestinal pathogens in mammals. Here, we demonstrate that the SpaC pilin of LGG causes intestinal epithelium injury by inducing cell pyroptosis and gut microbial dysbiosis in zebrafish. Dietary SpaC activates Caspase‐3−GSDMEa pathways in the intestinal epithelium, promotes intestinal pyroptosis and increases lipopolysaccharide (LPS)‐producing gut microbes in zebrafish. The increased LPS subsequently activates Gaspy2−GSDMEb pyroptosis pathway. Further analysis reveals the Caspase‐3−GSDMEa pyroptosis is initiated by the species‐specific recognition of SpaC by TLR4ba, which accounts for the species‐specificity of the SpaC‐inducing intestinal pyroptosis in zebrafish. The observed pyroptosis‐driven gut injury and microbial dysbiosis by LGG in zebrafish suggest that host‐specific beneficial/harmful mechanisms are critical safety issues when applying probiotics derived from other host species and need more attention.

Abstract We aimed to investigate the clinico-radiologic features of acute Marchiafava-Bignami disease (MBD) and its evolutionary process after effective treatment through subgroup comparison. The clinical and MRI data of 23 patients with acute MBD were retrospectively analyzed and divided into type A (12 cases, with entire callosal involvement) and type B (11 cases, with focal callosal involvement). The clinical assessments and MRI findings (before and after treatment) were compared between the two subtypes. Compared with type B, type A had lower MoCA (Montreal Cognitive Assessment) scores at admission (16.50 ± 1.73 vs 18.27 ± 1.68, P = 0.021) and were more common with extracallosal involvement (66.67% vs 18.18%, P = 0.036) and longer illness duration (18.3 ± 2.1 days vs 15.6 ± 2.4 days, P = 0.012). During the treatment, the residual lesion in the splenium was more common in type A (58.33% vs 9.09%, P = 0.027). After treatment, the MoCa scores of both subtypes gradually increased (P

Fish gut barrier damage under intensive culture model is a significant concern for aquaculture industry. This study aimed to investigate the effects of bile acids (BAs) on gut barriers in Micropterus salmoides. A germ-free (GF) zebrafish model was employed to elucidate the effects of the direct stimulation of BAs and the indirect regulations mediated by the gut microbiota on gut barrier functions. Four diets were formulated with BAs supplemented at 0, 150, 300 and 450 mg/kg, and these 4 diets were defined as control, BA150, BA300 and BA450, respectively. After 5 weeks of feeding experiment, the survival rate of fish fed with BA300 diet was increased (P 0.05). The results of the gut microbiota transferring experiment demonstrated an upregulation of gut barrier-related genes, including immunoglobulin Z/T (IgZ/T), IL-6, IL-1β and IL-10, by the gut microbiota transferred from the BA300 group compared with the control (P

Background: Clear cell renal cell carcinoma (ccRCC) is corelated with tumor-associated material (TAM), coagulation system and adipocyte tissue, but the relationships between them have been inconsistent. Our study aimed to explore the cut-off intervals of variables that are non-linearly related to ccRCC pathological T stage for providing clues to understand these discrepancies, and to effectively preoperative risk stratification. Methods: This retrospective analysis included 218 ccRCC patients with a clear pathological T stage between January 1st, 2014, and November 30th, 2021. The patients were categorized into two cohorts based on their pathological T stage: low T stage (T1 and T2) and high T stage (T3 and T4). Abdominal and perirenal fat variables were measured based on preoperative CT images. Blood biochemical indexes from the last time before surgery were also collected. The generalized sum model was used to identify cut-off intervals for nonlinear variables. Results: In specific intervals, fibrinogen levels (FIB) (2.63–4.06 g/L) and platelet (PLT) counts (>200.34 × 109/L) were significantly positively correlated with T stage, while PLT counts (

This study aimed to explore whether the substitution of basic pellet feed by different proportions of moist fermented pellet feed affect the growth performance, liver and gut health, and intestinal microbiota structure of common carp (Cyprinus carpio). The experiment was divided into 5 groups: the control group was fed with the basic pellet feed, and the treatment groups were fed with the feed that moist fermented pelleted feed (MFF) substituted 5% (MFF5), 10% (MFF10), 15% (MFF15) and 20% (MFF20) of the basic pellet feed. Feeding trial was lasted 8 weeks. The results showed that the feed efficiency of MFF10 groups was significantly higher than that of control group. MFF replacement had no significant effect on the weight again and survival rate of C. carpio compared with Control. In addition, MFF substitution showed that the liver anti-inflammatory factors TGF-β in MFF groups except MFF5 group showed a significant upward trend, liver IL-10 of MFF15 and MFF20 groups and intestinal TNF-α of MFF10 were significantly higher than those of control group. Moreover, the intestinal zo-1 of MFF5 and MFF10 groups, hepcidin of MFF5, and defensin in MFF5 and MFF10 were significantly elevated compared with the control (P

Lipoic acid ferulate (LAF) was synthesized and its anti-free radical ability in vitro was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonicacid) (ABTS) assays. Protective effects of LAF in stabilizing fish oil were tested, compared to antioxidants such as lipoic acid, ferulic acid and tert-butylhydroxyquinone (TBHQ) by measuring peroxide values, thiobarbituric acid reactants, p-anisidine values, nuclear magnetic resonance (NMR) spectra and gas chromatography–mass spectrometry (GC–MS) spectra of fish oil during accelerated storage (12 days, 80 °C). The inhibitory effect of these antioxidants on fish oil oxidation followed the order TBHQ ≧ LAF > ferulic acid > lipoic acid. In addition, the omega-3 polyunsaturated fatty acids were the first to be oxidized. The formation of oxidation products followed a first-order kinetic model, and the addition of LAF effectively reduced the reaction rate constants. Therefore, LAF can effectively slow down the formation of oxidative products and prolong the shelf life of fish oil.

Abstract Background Numerous studies have established that foreign language anxiety (FLA) has a significant impact on learners’ language acquisition and performance. FLA is a unique form of anxiety that occurs in response to a certain circumstance. Even though a growing amount of research has extended to the examination of skill-based anxiety in specific, such as listening, speaking, reading, and writing, little used corresponding skilled-based FLA scales to assess learners’ skill-based FLA at one group of learners. To fill a void in this line of research, the study aimed to explore learners’ primary FLA by comparing their four language skill-specific FLAs with four different skill-based FLA scales. Additionally, we wished to investigate the variables that influence learners’ FLA. Methods All participants in the study were first-year medical students. Individual instructors delivered and collected a total of 1023 questionnaires using an open questionnaire platform during normal English lessons in the mid-semester. SPSS 24.0 (Statistical Package for Social Science 24 version) was used to analyze all statistics. Internal validity tests were undertaken on each scale to ascertain the component structure of certain modified scales. The study employed the independent sample t-test and a statistical description to investigate students’ major FLA and its variables. Results With a mean value of 106.863, the predominant FLA arouses from English listening anxiety. English reading anxiety was the lowest, with a mean score of 62.726. Male and female students both demonstrated the greatest degree of FLA in English listening and the least anxiety in English reading. However, their mean difference was not statistically significant (t = 1.220). By comparing the mean scores for four skill-based FLAs across language proficiency groups, it became clear that the scores for the medium were much higher than the average, with average scores of ESA: 91.988, ELA: 106.864, EWA: 74.157, ERA: 62.726, respectively, and the higher-level group scored lower than the average. Students’ prior English learning achievements are negatively connected with their FLA, with r values of −.207 (ELA), −.143 (EWA), and − .204 (ERA). The self-evaluation of students’ English listening, writing, and reading abilities was considerably adversely connected with FLA, but the self-evaluation of their English-speaking abilities was favorably correlated with FLA. Conclusion A comparison of students’ FLA revealed that the primary skill-based FLA is related to English listening anxiety. Regardless of gender or language proficiency level, FLA was mainly driven by foreign language listening anxiety in all individuals. Prior language achievement and students’ self-evaluation are associated with their FLA.

To assessed the effects of solid-state fermentation product of yeast (SFPY) supplementation on high-fat diet (HFD) induced challenges on growth, hepatic lipid metabolism, epidermal mucus, intestine and liver health and gut microbiota in zebrafish (Danio rerio), four experimental diets were prepared for one-month-old zebrafish: basal diet (Control), high-fat diet (HFD), 0.5% SFPY (0.5 SFPY) or 1.0% SFPY (1.0 SFPY)-added HFD. After 3 weeks of feeding, the results illustrated that although HFD increased weight gain (WG), corresponding decreased the feed conversation ratio (FCR), it caused negative influences including liver steatosis, intestinal and liver damage in zebrafish. Compared with HFD group, 1.0% SFPY obviously promoted the lysozyme activity and complement 4 (C4) level on epidermal mucus (P

The gill is an important organ in fish that is involved in various physiological functions, including respiration, filter-feeding, ammonia nitrogen excretion, and osmoregulation. The physiological functions of gills are closely related to their structure, external feeding conditions, and environmental factors. Herein, we first briefly summarize the basic structure and functions of the gills of teleosts, then explain the structure and function of the gill barrier (as a microbial barrier, a chemical barrier, a physical barrier, and an immune barrier) in detail. Finally, we introduce the regulation of fish gill barrier health by ubiquitous feeding factors and environmental factors, and provide an outlook on the prospects of gill barrier health. We found that improving health through modulating feed factors is more convenient than improving environmental factors. This review increases our understanding of how nutrient composition and level in fish diet influences gill health and overall growth performance of fish.

Probiotics are reported to improve the nutrition, immunity, and health of fish. Nuclease can hydrolyze nucleic acids of probiotics to produce nucleotides. The present study investigated the effect of stabilized fermentation product of nuclease-treated Lactobacillus rhamnosus GCC-3 (GCC-3 NT) on growth, non-specific immunity, liver health, and gut microbiota of zebrafish (Danio rerio). Compared to the high-fat diet (HFD) group, GCC-3 NT did not affect the growth performance of zebrafish. However, GCC-3 NT treatment can significantly increase the lysozyme activity and the total antioxidant capacity of body surface mucus. In addition, dietary GCC-3 NT significantly reduced the content of hepatic triglycerides (TAG) in zebrafish while significantly increased the expression of acyl-coenzyme A oxidases 3 (ACOX3) and proliferator-activated receptor γ coactivator 1α (PGC1α) compared with the HFD group. The 16S rRNA gene sequencing showed that GCC-3 NT reduced the relative abundance of Actinobacteria while increased Firmicutes at the phylum level. The relative abundance of Rhodococcus was significantly decreased and Lactobacillus and Staphylococcus abundance were significantly increased in the GCC-3 NT group compared to the HFD group. Furthermore, PCoA analysis showed GCC-3 NT diet had a significant effect on the autochthonous microbiota compared to the HFD diet. Together, our results showed that nuclease-treated L. rhamnosus fermentation product can improve the immunity, liver health and gut microbiota of zebrafish, suggesting that it can be potentially used as a functional feed additive for aquaculture.

This study was to investigate the effect of medium-chain fatty acids products Aromabiotic® Shrimp (ABS) on growth, gut and hepatopancreas health, gut microbiota and resistance to bacterial infection and adverse environment of white shrimp. Firstly, white shrimp were divided into five groups: control, ABS0.5, ABS1, ABS2, and ABS5 (with 0, 0.5, 1, 2 and 5 g/kg ABS in feed respectively). After 5-week feeding, there was no significant difference in weight gain, feed conversion ratio and survival among groups. However, ABS diets significantly improved the survival of the white shrimp after Vibrio parahaemolyticus challenge (ABS5, P

Abstract Background Cervical cancer shows great differences in depth of invasion, metastasis, and other biological behaviors. The location of the lesion is special, so it is usually difficult to determine the clinical stage. This study aimed to explore the clinical value of magnetic resonance imaging (MRI) and tumor serum markers for the preoperative diagnosis of cervical cancer lymph node metastasis and para-uterine invasion. Methods A total of 200 patients with cervical cancer admitted to our hospital from January 2019 to January 2020 were collected as the research subjects. Comparing the diagnosis results of preoperative MRI scan, serum tumor markers, and postoperative pathological examination using single factor comparison, we determined the MRI scan results, the comprehensive matching rate between serum tumor markers (squamous cell carcinoma antigen (SCCA), carbohydrate antigen 125 (CA125)) and postoperative pathological results, and the differences of sensitivity, specificity, and accuracy in the prediction of lymph node metastasis and para-uterine infiltration of cervical cancer. Results The levels of SCCA and CA125 in patients with para-uterine invasion and lymph node metastasis were higher than those of patients without invasion and metastasis. Among them, the level of SCCA was significantly different (P0.05), so MRI combined with serum SCCA was selected for combined diagnosis in the later period. The sensitivity, specificity, and accuracy of MRI diagnosis of cervical cancer and para-uterine infiltrating lymph node metastasis and metastasis were 55.2, 91.6, and 89.5% and 55.2, 91.6, and 89.5%, respectively. These data in MRI combined with serum SCCA were 76.3, 95.3, and 94.3% and 63.2, 96.0, and 95.1%, respectively. The accuracy of tumor markers combined with MRI in the diagnosis of cervical cancer lymph node metastasis and para-uterine invasion was higher than that of MRI. Conclusions MRI combined with serum SCCA can more accurately identify cervical cancer lymph node metastasis and para-uterine invasion compared with MRI alone. Tumor marker combined with MRI diagnosis is an important auxiliary method for cervical cancer treatment and can provide comprehensive and reliable clinical evidence for evaluation before cervical cancer surgery.

β-glucan has been used as immunostimulant for fish. However, the effect of yeast β-glucan on viral infections has been less studied in fish. In this study, we investigated the effects of β-glucan on the resistance of zebrafish against spring viraemia of carp virus (SVCV) and elucidated the underlying mechanisms. Zebrafish were fed with a control diet or diet supplemented with 0.01% and 0.025% β-glucan for 2 weeks, and were challenged by SVCV. Zebrafish embryonic fibroblast (ZF4) cells were treated with 5 μg/mL β-glucan and were infected by SVCV. We further investigated the effect of β-glucan on autophagy level post SVCV infection. The intestinal microbiota was evaluated by 16S rRNA gene pyrosequencing. Results showed that dietary supplementation of 0.025% β-glucan significantly increased survival rate of zebrafish compared with control group after SVCV challenge (P < 0.05). Dietary β-glucan significantly increased the expression of genes related to type I IFN antiviral immune pathway in the spleen of zebrafish after viral infection, including type I IFN genes (ifnφ1, ifnφ2, ifnφ3), IFN-stimulated genes (mxb, mxc), as well as other genes involved in the IFN signaling pathway, including tlr7, rig1, mavs, irf3 and irf7. Morpholino knockdown of type I IFN receptors dampened the antiviral effect of β-glucan in zebrafish larvae, indicating that β-glucan-mediated antiviral function was at least partially dependent on IFN immune response. Furthermore, β-glucan can inhibit the replication of SVCV in ZF4 cells. However, β-glucan did not stimulate type I IFN antiviral response in ZF4 cells, and the antiviral effect of β-glucan in ZF4 was independent of Myd88. Interestingly, β-glucan induced autophagy in ZF4 cells after SVCV infection. Inhibition of autophagy blocked the antiviral effect of β-glucan in ZF4 cells. Lastly, dietary β-glucan changed the composition of intestinal microbiota in zebrafish, with reduced abundance of Proteobacteria and an enrichment of Fusobacteria and Firmicutes. To sum up, our results indicate that the β-glucan enhanced resistance of zebrafish against SVCV and the mechanism involved stimulation of type I IFN antiviral immune response of fish after viral infection.

Spring viremia of carp virus (SVCV) can cause high mortality of fish. The aim of this study was to investigate the effects of Lactobacillus rhamnosus GCC-3 exopolysaccharides (GCC-3 EPS) on zebrafish (Danio rerio) infected with SVCV and elucidate the underlying mechanisms. Zebrafish were fed with a control diet or diet supplemented with 0.5% and 1% of GCC-3 EPS for 2 weeks. The results showed that supplementation of GCC-3 EPS significantly improved the survival rate of zebrafish compared with the control group. In addition, dietary 0.5% and 1% GCC-3 EPS significantly up-regulated the expression of genes related to type I interferon (IFN) antiviral immunity. Consistent with in vivo results, GCC-3 EPS significantly inhibited SVCV replication in zebrafish embryonic fibroblast (ZF4) cells while significantly increased the expression of type I IFN signaling pathway related genes. Furthermore, knocking down TANK-binding kinase 1 significantly blocked the antiviral effect of GCC-3 EPS. Dietary GCC-3 EPS improved gut microbiota, and the culture supernatant of GCC-3 EPS-associated microbiota significantly inhibited SVCV replication in ZF4 cells compared with the control-microbiota counterpart. In conclusion, our results indicate that dietary GCC-3 EPS can improve the resistance of zebrafish against SVCV infection, and the mechanism may involve enhanced type I interferon signaling.

High-fat diets (HFD) are harmful to fish health. Probiotics are commonly utilized to improve fish nutrition metabolism, immune response, and health. Nucleic acids of the probiotic bacterium can be hydrolyzed by nuclease to generate nucleotides. The present study aimed to evaluate the effects of stabilized fermentation product of nuclease-treated Cetobacterium somerae XMX-1 [XMX-1 (N)] on growth, non-specific immunity, and liver health of zebrafish (Danio rerio). Compared to the HFD group, 100 g/kg XMX-1 (N) significantly increased weight gain and decreased feed conversion ratio (FCR). However, 5 or 10 g/kg XMX-1 (N) had no influence on zebrafish growth. In addition, supplementation of 100 g/kg XMX-1 (N) significantly increased lysozyme activity and total antioxidant capacity in skin mucus, and the expression of inflammation related genes interleukin 1 beta (IL-1β), interleukin 10 (IL-10), and interleukin 6 (IL-6) in the gut as well as fatty acid oxidation related genes uncoupling protein 2 (UCP2) and proliferator-activated receptor γ coactivator 1α (PGC1α) in the liver, while decreased the content of hepatic triacylglycerol (TAG) in zebrafish. The gene sequencing, 16S rRNA, showed that 100 g/kg XMX-1 (N) enhanced the relative abundance of Firmicutes while lowered Proteobacteria and Actinobacteria. 10 g/kg XMX-1 (N) significantly increased lysozyme activity and complement component 4 (C4) in skin mucus, and intestinal expression of inflammation-related genes. In the 5 g/kg XMX-1 (N) group, however, only an increase in C4 level in skin mucus was observed. Together, these results reveal that dietary supplementation with nuclease-treated C. somerae XMX-1 (N) has a dose-dependent beneficial effect on fish health.

As the front end of the intake system, the intake dirty pipe is responsible for delivering sufficient and stable air to the air filter. Therefore, in order to meet the requirements of low intake resistance, it is necessary to correspondingly improve the flow resistance performance of the intake dirty pipe. In this study, the main research object was the intake pipe in the intake system of gasoline engine vehicles, and the internal gas flow field was simulated and analyzed. The results show that there are clear discrete velocity regions at the inlet and elbow, which affect the uniformity of the overall fluid flow and cause a certain pressure loss. After structural optimization, the total pressure difference at the inlet and outlet of the pipeline was reduced by 22.67% compared to the original model, and the total pressure loss was significantly reduced. A simplified model was used to make samples of the intake dirty pipes before and after performance improvement, and flow resistance tests were conducted respectively. The difference between test data and simulation data is within a reasonable range, and the simulation results are relatively reliable.

A biocontrol Bacillus velezensis strain, NT35, was isolated from the rhizosphere soil of ginseng, and its sterile filtrate was obtained through a 0.22 μm filter which had a significant inhibitory effect against Ilyonectria robusta, which causes rusty root rot in Panax ginseng. In order to obtain the best sterile filtrate, the medium fermentation conditions of the strain NT35 were optimized using response surface methodology (RSM), and the best composition was obtained. Therefore, the fermentation medium was composed of yeast extract powder 2.5%, cornmeal 1.5%, K2HPO4 1.5%, and (NH4)2SO4 2.5%. The optimal inoculum amount was 6%, at an initial pH value of 7.0 and culturing at 34 °C at 180 rpm. The antifungal protein 1-4-2F was obtained through precipitation via 30% (NH4)2SO4 precipitation, desalting by Sephadex G-25, ion-exchange chromatography, and gel filtration chromatography. Tricine-SDS-PAGE showed that the purified protein had a relative molecular weight of approximately 6.5 kDa. The protein 1-4-2F was relatively stable and had better antifungal activity at pH 4–10 and 20–100 °C under ultraviolet irradiation of 30 W. The amino acid sequence of protein 1-4-2F was obtained using mass spectrometry, and had 100% similarity to a hypothetical protein from B. velezensis YAU B9601-Y2 (Accession No: AFJ62117). Its molecular weight was 10.176 kDa, the isoelectric point was 9.08, and its sequence coverage reached 49%. The EC50 value of the protein 1-4-2F against I. robusta was 1.519 μg·mL−1. The mycelia morphology of I. robusta changed significantly after treatment with antifungal protein under microscopic observation; the branches of the mycelia increased, distorted, partially swelled into a spherical or elliptical shape, and even ruptured; and the cells became vacuoles.

The capability of carbohydrate utilization in fish is limited compared to mammals. It has scientific and practical significance to improve the ability of fish to use carbohydrates. The efficiency of dietary carbohydrate utilization varies among fish with different feeding habits, which are associated with differential intestinal microbiota. In this study, we found that zebrafish fed with omnivorous diet (OD) and herbivorous diet (HD) showed better glucose homeostasis compared with carnivorous diet (CD) fed counterpart and the differential glucose utilization efficiency was attributable to the intestinal microbiota. The commensal bacterium Cetobacterium somerae, an acetate producer, was enriched in OD and HD groups, and administration of C. somerae in both adult zebrafish and gnotobiotic larval zebrafish models resulted in improved glucose homeostasis and increased insulin expression, supporting a causative role of C. somerae enrichment in glucose homeostasis in fish. The enrichment of C. somerae was constantly associated with higher acetate levels, and dietary supplementation of acetate promotes glucose utilization in zebrafish, suggesting a contribution of acetate in the function of C. somerae. Furthermore, we found that the beneficial effect of both acetate and C. somerae on glucose homeostasis was mediated through parasympathetic activation. Overall, this work highlights the existence of a C. somerae-brain axis in the regulation of glucose homeostasis in fish and suggests a role of acetate in mediating the axis function. Our results suggest potential strategies for improvement of fish carbohydrate utilization.

Probiotics are an eco-friendly alternative to antibiotics and play an important role in ensuring the sustainability of aquaculture. The aim of the present study was to investigate the effects of Saccharomyces cerevisiae on the growth, intestinal and liver health, intestinal microbiota, and disease resistance of channel catfish (Ictalurus punctatus). Channel catfish were randomly allotted into two treatments, control group (basal diet) and SCC group (basal diet with 2% Saccharomyces cerevisiae culture), and fed for 12 weeks. The results showed that the weight gain of SCC group was significantly increased (P P > 0.05). In addition, the survival rate of channel catfish was significantly increased in SCC group after being challenged with mixture of A. veronii HM091 and A. hydrophila NJ-1. In conclusion, the supplementation of Saccharomyces cerevisiae culture improved the growth, intestinal and liver health and disease resistance of channel catfish.

Succinate is widely used in the food and feed industry as an acidulant, flavoring additive, and antimicrobial agent. This study investigated the effects of dietary succinate on growth, energy budget, nutritional metabolism, protein succinylation, and gut microbiota composition of zebrafish. Zebrafish were fed a control-check (0% succinate) or four succinate-supplemented diets (0.05, 0.10, 0.15, and 0.2%) for 4 weeks. The results showed that dietary succinate at the 0.15% additive amount (S0.15) can optimally promote weight gain and feed intake. Whole body protein, fat, and energy deposition increased in the S0.15 group. Fasting plasma glucose level decreased in fish fed the S0.15 diet, along with improved glucose tolerance. Lipid synthesis in the intestine, liver, and muscle increased with S0.15 feeding. Diet with 0.15% succinate inhibited intestinal gluconeogenesis but promoted hepatic gluconeogenesis. Glycogen synthesis increased in the liver and muscle of S0.15-fed fish. Glycolysis was increased in the muscle of S0.15-fed fish. In addition, 0.15% succinate-supplemented diet inhibited protein degradation in the intestine, liver, and muscle. Interestingly, different protein succinylation patterns in the intestine and liver were observed in fish fed the S0.15 diet. Intestinal proteins with increased succinylation levels were enriched in the tricarboxylic acid cycle while proteins with decreased succinylation levels were enriched in pathways related to fatty acid and amino acid degradation. Hepatic proteins with increased succinylation levels were enriched in oxidative phosphorylation while proteins with decreased succinylation levels were enriched in the processes of protein processing and transport in the endoplasmic reticulum. Finally, fish fed the S0.15 diet had a higher abundance of Proteobacteria but a lower abundance of Fusobacteria and Cetobacterium. In conclusion, dietary succinate could promote growth and feed intake, promote lipid anabolism, improve glucose homeostasis, and spare protein. The effects of succinate on nutritional metabolism are associated with alterations in the levels of metabolic intermediates, transcriptional regulation, and protein succinylation levels. However, hepatic fat accumulation and gut microbiota dysbiosis induced by dietary succinate suggest potential risks of succinate application as a feed additive for fish. This study would be beneficial in understanding the application of succinate as an aquatic feed additive.

Being highly unsaturated, n-3 long-chain polyunsaturated fatty acids (LC-PUFAs) are prone to lipid peroxidation. In this study, zebrafish were fed with low-fat diet (LFD), high-fat diet (HFD), or 2% DHA-supplemented HFD (HFDHA2.0). To study the possible negative effects of the high level of dietary DHA, growth rates, blood chemistry, liver histology, hepatic oxidative stress, apoptosis, and inflammatory processes were assessed. The cell studies were used to quantify the effects of DHA and antioxidant on cellular lipid peroxidation and viability. The possible interaction between gut microbiota and zebrafish host was evaluated in vitro. HFDHA2.0 had no effect on hepatic lipid level but induced liver injury, oxidative stress, and hepatocellular apoptosis, including intrinsic and death receptor-induced apoptosis. Besides, the inclusion of 2% DHA in HFD increased the abundance of Proteobacteria in gut microbiota and serum endotoxin level. In the zebrafish liver cell model, DHA activated intrinsic apoptosis while the antioxidant 4-hydroxy-Tempo (tempo) inhibited the pro-apoptotic negative effects of DHA. The apoptosis induced by lipopolysaccharide (LPS) was unaffected by the addition of tempo. In conclusion, the excess DHA supplementation generates hepatocellular apoptosis-related injury to the liver. The processes might propagate along at least two routes, involving lipid peroxidation and gut microbiota-generated LPS.

Intensive aquaculture practices compromise the health of fish. Probiotics especially those isolated from aquatic animals play important roles in improving fish health. The aim of the study was to evaluate the effects of stabilized fermentation product of Cetobacterium somerae (XMX-1) on the growth performance, gut and liver health of common carp. A total of 300 carps (initial weight of 2.32 ± 0.02 g) were divided into the control (fed a basal diet) and XMX-1 groups (fed a basal diet with 2 g/kg, 3 g/kg, 4 g/kg or 5 g/kg XMX-1 diet). After 8-week feeding, growth performance, serum lipopolysaccharide (LPS), diamine oxidase activity (DAO), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were evaluated. The intestinal total superoxide dismutase (SOD) activity, the expression of gut health related genes was tested. In addition, the liver triacylglycerol (TAG) and the expression of liver lipid metabolism related genes were conducted. Results showed that XMX-1 addition had no effect on the growth performance of carps at a supplementation level up to 5 g/kg (P > 0.05). However, dietary XMX-1 at addition levels ranging from 2 g/kg to 5 g/kg reduced serum LPS and DAO. Furthermore, all XMX-1 additions significantly increased total SOD activity compared with the control group (P

Abstract Quorum quenching (QQ) blocks bacterial cell-to-cell communication (i.e., quorum sensing), and is a promising antipathogenic strategy to control bacterial infection via inhibition of virulence factor expression and biofilm formation. QQ enzyme AiiO-AIO6 from Ochrobactrum sp. M231 has several excellent properties and shows biotherapeutic potential against important bacterial pathogens of aquatic species. AiiO-AIO6 can be secretory expressed in Bacillus subtilis via a non-classical secretion pathway. To improve AiiO-AIO6 production, four intracellular protease-deletion mutants of B. subtilis 1A751 were constructed by individually knocking out the intracellular protease-encoding genes (tepA, ymfH, yrrN and ywpE). The AiiO-AIO6 expression plasmid pWB-AIO6BS was transformed into the B. subtilis 1A751 and its four intracellular protease-deletion derivatives. Results showed that all recombinant intracellular protease-deletion derivatives (BSΔtepA, BSΔymfH, BSΔyrrN and BSΔywpE) had a positive impact on AiiO-AIO6 production. The highest amount of AiiO-AIO6 extracellular production of BSΔywpE in shake flask reached 1416.47 U/mL/OD600, which was about 121% higher than that of the wild-type strain. Furthermore, LC–MS/MS analysis of the degrading products of 3-oxo-C8-HSL by purification of AiiO-AIO6 indicated that AiiO-AIO6 was an AHL-lactonase which hydrolyzes the lactone ring of AHLs. Phylogenetic analysis showed that AiiO-AIO6 was classified as a member of the α/β hydrolase family with a conserved “nucleophile-acid-histidine” catalytic triad. In summary, this study showed that intracellular proteases were responsible for the reduced yields of heterologous proteins and provided an efficient strategy to enhance the extracellular production of AHL lactonase AiiO-AIO6.

Abstract Thelohanellus kitauei, is a member of obligate parasitic myxozoans, which causes intestinal giant-cystic disease of common carp (Cyprinus carpio) and has resulted in significant economic losses in carp farms. Cystatin secreted by parasites can regulate the immune response of host to facilitate parasite’s survival. In this study, the secretory TK-cystatin gene, encoding a protein of 120 amino acid residues (13.65 kDa), was cloned from T. kitauei genome. Phylogenetic analysis showed that TK-cystatin gene is closely related to the cystatin-A from Hydra vulgaris. Multiple sequence alignment revealed that TK-cystatin had three conserved motifs: N-terminal G19G20, Q73VVAG77, and C-terminal L102P103. Molecular docking between TK-cystatin and three cysteine proteases showed a lower binding energy (− 13 KJ/mol) with cathepsin L whereas a higher binding energy (− 8.6 KJ/mol) with cathepsin B. TK-cystatin gene was expressed in Escherichia coli. Activity assays revealed that TK-cystatin has stronger inhibitory activity on endopeptidases (papain and cathepsin L) and weaker inhibitory activity on exopeptidase (cathepsin B). TK-cystatin was stable under the condition of acidity or alkalinity or below 57 °C. This study laid a foundation for the design and development of the anti-T. kitauei vaccine in carp culture in the future.

Water distribution networks (WDNs) is crucial to ensure social operations and economic activities. However, WDNs are highly sensitive and vulnerable to disasters. The aim of this study is to mitigate the catastrophic consequences of cascading failures in WDNs. A flow-based WDN cascading failure model is built. The extended multi-objective particle swarm optimization model is developed to resist cascading failures and improve resilience. This model takes pipe diameter as the decision variable to minimize cost and maximize pressure deficit. Water balance, pressure, and standard pipe diameter are the constraints. The classical optimal scenario (COS) and the cascading failure scenario (CFS) are simulated. The model is applied to a small and medium-sized benchmarked WDN. Results show that the extended PSO can find the optimal solution on the benchmarked WDN. The Pareto fronts are obtained. Compare to the Pareto fronts between COS and CFS, the pressure deficit under CFS is significantly reduced, and the cost is reduced while the same pressure deficit increased. Different tolerance parameters are tested. The small network is not sensitive to the tolerance parameter, but the medium-sized network is sensitive. The model evaluates a variety of conflicting goals, which help designers and water managers resist cascading failures in WDNs.

The growth performance of cultured aquatic animals is directly related to the economic benefit of the aquaculture industry. Quenching enzyme AiiO-AIO6 could degrade quorum sensing signal molecules N-acylhomoserine lactone (AHL), in this work, the effects of this AiiO-AIO6 on the growth of zebrafish was studied, the control group and AiiO-AIO6 additive group were set up with 120 fish in each group, and the feeding experiment was carried out for three weeks. The following results were obtained by observation of intestinal structure and morphology, quantitative PCR, gut microbes sequencing analysis and transfer, etc. The results showed that the final weight, weight gain rate and specific growth rate were significantly increased and feed conversion ratio and feeding rate of AiiO-AIO6 treated group were significantly decreased. Intestinal digestive enzyme assay showed that there was no significant difference in amylase, lipase and protease activities between the AiiO-AIO6 and control group. Hematoxylin and eosin (H&E) staining of intestinal morphology showed that the height of villus, the number of goblet cells and the height of columnar epithelial cells were significantly increased in the AiiO-AIO6 group. In addition, the relative expression levels of intestinal nutrient transporters Pept1a, GLUT2 and FATP1-a were also significantly increased. The analysis of intestinal microbiota structure and short-chain fatty acids showed that the addition of AiiO-AIO6 could change intestinal microbiota structure and increase the contents of acetic acid and isovalerate. The expression of growth-related genes in intestine, liver and muscle of two groups showed that growth hormone GH, GH receptor GHra, insulin-like growth factor IGF-I and myogenic factor Myf5 of AiiO-AIO6 group were significantly up-regulated. Results in the germ-free zebrafish model showed that the expression of growth-related genes was not directly regulated by AiiO-AIO6, but was mediated by the action of active intestinal microbiota. Overall, our data reflected that AiiO-AIO6 can promote the growth performance of zebrafish, and AiiO-AIO6 is a potential functional additive to make aquaculture efficient and high-yielding.

With the widespread use of high-fat diets (HFDs) in aquaculture, fatty livers are frequently observed in many fish species. The aim of this study was to investigate if docosahexaenoic acid (DHA) could be used to reduce the fatty liver in zebrafish generated by a 16% soybean oil-HFD over 2 weeks of feeding. The DHA was added to iso-lipidic HFD at 0.5, 1.0, and 2.0% of diet. Supplementation of DHA reduced growth and feed efficiency in a dose dependent manner being lowest in the HFDHA2.0 group. Hepatic triglyceride (TG) in zebrafish fed 0.5% DHA-supplemented HFD (HFDHA0.5) was significantly lower than in the HFD control. Transcriptional analyses of hepatic genes showed that lipid synthesis was reduced, while fatty acid β-oxidation was increased in the HFDHA0.5 group. Furthermore, the expression of Cyclin D1 in liver of zebrafish fed HFDHA0.5 was significantly reduced compared to that in fish fed HFD. In zebrafish liver cells, Cyclin D1 knockdown and blocking of Cyclin D1-CDK4 signal led to inhibited lipid biosynthesis and elevated lipid β-oxidation. Besides, DHA-supplemented diet resulted in a rich of Proteobacteria and Actinobacteriota in gut microbiota, which promoted lipid β-oxidation but did not alter the expression of Cyclin D1 in germ-free zebrafish model. In conclusion, DHA not only inhibits hepatic lipid synthesis and promotes lipid β-oxidation via Cyclin D1 inhibition, but also facilitates lipid β-oxidation via gut microbiota. This study reveals the lipid-lowering effects of DHA and highlights the importance of fatty acid composition when formulating fish HFD.

Fatty liver and intestinal barrier damage were widespread in most farmed fish, which severely restrict the development of aquaculture. Therefore, there was an urgent need to develop green feed additives to maintain host liver and intestinal health. In this study, a probiotic pili-like protein, Amuc_1100 (AM protein), was anchored to the surface of Lactococcus lactis ZHY1, and the effects of the recombinant bacteria AM-ZHY1 on liver fat accumulation and intestinal health were evaluated. Zebrafish were fed a basal diet, high-fat diet, and high-fat diet with AM-ZHY1 (108 cfu/g) or control bacteria ZHY1 for 4 weeks. Treatment with AM-ZHY1 significantly reduced hepatic steatosis in zebrafish. Quantitative PCR (qPCR) detection showed that the expression of the lipogenesis [peroxisome-proliferator-activated receptors (PPARγ), sterol regulatory element-binding proteins-1c (SREBP-1c), fatty acid synthase (FAS), and acetyl-CoA carboxylase 1 (ACC1)] and lipid transport genes (CD36 and FABP6) in the liver were significantly downregulated (p < 0.05), indicating that AM-ZHY1 could reduce liver fat accumulation by inhibiting lipid synthesis and absorption. Moreover, supplementing AM-ZHY1 to a high-fat diet could significantly reduce serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, indicating that liver injury caused by high-fat diets was improved. The expression of tumor necrosis factor (TNF)-a and interleukin (IL)-6 in the liver decreased significantly (p < 0.05), while IL-1β and IL-10 did not change significantly in the AM-ZHY1 group. Compared to the high-fat diet-fed group, the AM-ZHY1 group, but not the ZHY1 group, significantly increased the expression of intestinal tight junction (TJ) proteins (TJP1a, claudina, claudin7, claudin7b, claudin11a, claudin12, and claudin15a; p < 0.05). Compared to the high-fat diet group, the Proteobacteria and Fusobacteria were significantly reduced and increased in the AM-ZHY1 group, respectively. In conclusion, the recombinant bacteria AM-ZHY1 has the capacity to maintain intestinal health by protecting intestinal integrity and improving intestinal flora structure and improving fatty liver disease by inhibiting lipid synthesis and absorption. This study will lay a foundation for the application of AM protein in improving abnormal fat deposition and restoring the intestinal barrier in fish.

Summary: Propionate and propionyl-CoA accumulation have been associated with the development of mitochondrial dysfunction. In this study, we show that propionate induces intestinal damage in zebrafish when fed a high-fat diet (HFD). The intestinal damage was associated with oxidative stress owing to compromised superoxide dismutase 2 (Sod2) activity. Global lysine propionylation analysis of the intestinal samples showed that Sod2 was propionylated at lysine 132 (K132), and further biochemical assays demonstrated that K132 propionylation suppressed Sod2 activity. In addition, sirtuin 3 (Sirt3) played an important role in regulating Sod2 activity via modulating de-propionylation. Finally, we revealed that intestinal oxidative stress resulting from Sod2 propionylation contributed to compositional change of gut microbiota. Collectively, our results in this study show that there is a link between Sod2 propionylation and oxidative stress in zebrafish intestines and highlight the potential mechanism of intestinal problems associated with high propionate levels.

The electrochemical formation mechanism of microdroplets formed around a primary droplet of 3.5% NaCl solution on an iron-plated film was investigated by quartz crystal microbalance (QCM) and concentric three-electrode array (CTEA) measurements. During the initial stage, the microdroplets mainly originate from evaporation owing to cathodic polarization and electric current of the localized corrosion cell under the primary droplet. The maximal electrochemical potential difference between the anode and cathode was measured to be 0.36 V and acted as the driving force for the formation of microdroplets. The maximums of anodic and cathodic electric current density of pure iron under the NaCl droplet are 764 and −152 μA/cm2, respectively. Propagation of microdroplets in the developing stage attributes to horizontal movement of the electrolyte, water evaporation, and recondensation from primary and capillary condensation from moist air. The results of the study suggest that the initiation and propagation of microdroplets could promote and accelerate marine atmospheric corrosion.

Plant proteins are widely used for fish meal replacement in aquafeeds, but anti-nutritional factors in plant protein reduce fish growth performance and impair fish health. The present work aimed to study the effects of improving fish meal replacement percentage with ultra-micro ground mixed plant proteins (uPP) on growth, gut and liver health of common carp. Carps were fed with a practical basal diet with partial fish meal replacement by plant proteins or the basal diet supplemented with 2.5 % or 5% uPP for 16-week. Results indicated that uPP addition did not affect growth and survival of common carp at a supplementation level up to 5% (p > 0.05). However, 5% uPP up-regulated the intestinal expression of inflammation related genes (p < 0.05) and reduced HIF-1α expression (p < 0.05). Moreover, dietary 5% uPP increased serum ALT (p = 0.06) and AST level (p < 0.05) and up-regulated liver expressions of inflammation related genes (p < 0.05). The Simpson diversity index of gut microbiota was lower in 5% uPP group compared to control (p < 0.05). The relative abundance of Fusobacteria and Cetobacterium was lower (p < 0.05), while Proteobacteria including Shewanella and Citrobacter was higher in the 5% uPP group compared to control (p < 0.05). In contrast, 2.5 % uPP did not increase inflammatory and injury parameters in fish intestine and liver, but rather improved the expression of occludin and defensin in the intestine compared with control (p < 0.05). Moreover, no significant differences were found in gut microbiota between 2.5 % uPP group and control. Together, our study suggests that low-level uPP addition can be adopted to further improve fish meal replacement, while dietary 5% uPP impairs gut and liver health of common carp and negatively affects intestinal microbiota.

Lactobacilli comprise an important group of probiotics for both human and animals. The emerging concern regarding safety problems associated with live microbial cells is enhancing the interest in using cell components and metabolites derived from probiotic strains. Here, we define cell structural components and metabolites of probiotic bacteria as paraprobiotics and postbiotics, respectively. Paraprobiotics and postbiotics produced from Lactobacilli consist of a wide range of molecules including peptidoglycans, surface proteins, cell wall polysaccharides, secreted proteins, bacteriocins, and organic acids, which mediate positive effect on the host, such as immunomodulatory, anti-tumor, antimicrobial, and barrier-preservation effects. In this review, we systematically summarize the paraprobiotics and postbiotics derived from Lactobacilli and their beneficial functions. We also discuss the mechanisms underlying their beneficial effects on the host, and their interaction with the host cells. This review may boost our understanding on the benefits and molecular mechanisms associated with paraprobiotics and probiotics from Lactobacilli, which may promote their applications in humans and animals.

The presence of healthy gut microbiota in the gastrointestinal tract of fish is important for the optimal function of gut, which plays a significant role in the host growth and health. The aim of the present study was to investigate the effect of dietary stress worry free (SWF®) on growth, feed utilization and disease resistance of hybrid sturgeon (Acipenser baerii x Acipenser schrenckii). Sturgeon were fed for three weeks with SWF® supplemented or basal diet. The weight gain and FCR of sturgeon fed on the diet supplemented with SWF® were significantly improved (P

Abstract In this study, we investigated the secretion mechanism of the hyper-secretion signal peptide-lacking β-xylosidase PtXyl43, a non-classically secreted protein, from the fungus Paecilomyces thermophila in Escherichia coli BL21(DE3). PtXyl43 secretion is a two-step process, and the second step is accompanied by cell periplasmic leakage, indicating that PtXyl43 secretion is the result of semi-specific secretion. Homology modeling of PtXyl43 suggested that PtXyl43 had a canonical GH43 family β-xylosidase structure containing five blades. Seventeen blade deletions or circular mutants were designed to identify the conformational motif(s) involved in secretion. These mutants were expressed as recombinant, codon-optimized proteins in E. coli. Notably, only mutants containing blades 2–4 were effectively secreted. Blades 2–4 are necessary for secretion, but it appears that blade 1 or 5 must be present to maintain the structure of blades 2–4. Simultaneous deletion of blades 1 and 5 dramatically reduces excretion. The covalent and sequential linking of blades of 2, 3 and 4 are important for the excretion of mutants, as separate blades of 2 and 3 or 3 and 4 abolishes excretion. Fusion with PtXyl43 promotes the excretion of GFP from the periplasm to the extracellular milieu, which suggested that PtXyl43 had the potential to carry proteins. This study provides new insights into secretory mechanism of secretable signal peptide-lacking proteins in E. coli. To our knowledge, this is the first to definitively identify the conformational determinants for secretion of a signal peptide-lacking GH43 family β-xylosidase. This finding also has application potential for the secretion of recombinant proteins.

Abstract Lytic polysaccharide monooxygenases (LPMOs) can oxidize recalcitrant polysaccharides and boost the conversion of the second most abundant polysaccharide chitin by chitinase. In this study, we aimed to achieve the efficient extracellular production of Serratia marcescens LPMO CBP21 and Aeromonas veronii B565 chitinase Chi92 by Escherichia coli. Twelve signal peptides reported with high secretion efficiency were screened to assess the extracellular production efficiency of CBP21 and Chi92, with glycine used as a medium supplement. The results showed that PelB was the most productive signal peptide for the extracellular production of CBP21 and Chi92 in E. coli. Furthermore, CBP21 facilitated the degradation of the three chitin substrates (colloidal chitin, β-chitin, and α-chitin) by Chi92. This study will be valuable for the industrial production and application of the two enzymes for chitin degradation.