Expression and characterization of a novel chitinase with antifungal activity from a rare actinomycete, Saccharothrix yanglingensis Hhs.015.

Saccharothrix yanglingensis Hhs.015, a new type of rare actinomycete, was isolated from the roots of cucumber. A novel chitinase gene was cloned from S. yanglingensis Hhs.015 and overexpressed as a soluble protein Chi6769 (77.9 kDa) in Escherichia coli. Chi6769 was purified by HisTrap HP affinity chromatography with optimal pH of 7.0. The enzymatic hydrolysis assay revealed that Chi6769 was capable of hydrolyzing chitin to (GlcNAc)3, (GlcNAc)2 and GlcNAc. (GlcNAc)2 was the main hydrolyzate. The antifungal activity result showed that Chi6769 exhibited strong antifungal activity toward Valsa mali 03-8. Overall, Chi6769 was potential to be a novel biofunctional chitinase that could be used as a biological agent in the control of plant diseases.

Study on influencing factors of carbon emissions from energy consumption of Shandong Province of China from 1995 to 2012.

Carbon emissions from energy consumption of Shandong province from 1995 to 2012 are calculated. Three zero-residual decomposition models (LMDI, MRCI and Shapley value models) are introduced for decomposing carbon emissions. Based on the results, Kendall coordination coefficient method is employed for testing their compatibility, and an optimal weighted combination decomposition model is constructed for improving the objectivity of decomposition. STIRPAT model is applied to evaluate the impact of each factor on carbon emissions. The results show that, using 1995 as the base year, the cumulative effects of population, per capita GDP, energy consumption intensity, and energy consumption structure of Shandong province in 2012 are positive, while the cumulative effect of industrial structure is negative. Per capita GDP is the largest driver of the increasing carbon emissions and has a great impact on carbon emissions; energy consumption intensity is a weak driver and has certain impact on carbon emissions; population plays a weak driving role, but it has the most significant impact on carbon emissions; energy consumption structure is a weak driver of the increasing carbon emissions and has a weak impact on carbon emissions; industrial structure has played a weak inhibitory role, and its impact on carbon emissions is great.

Metabolites 13,14-Dihydro-15-keto-PGE2 Participates in Bifidobacterium animalis F1-7 to Alleviate Opioid-Induced Constipation by 5-HT Pathway.

SCOPE: People suffer from constipation caused by many factors, including constipation (Opioid-Induced Constipation, OIC) during analgesic treatment. Microorganisms may be a potent solution to this problem, but the mechanism is still unclear. METHODS AND RESULTS: Based on models in vivo and in vitro, the potential mechanism involving Bifidobacterium animalis F1-7 (B. animalis F1-7), screened in the previous studies, is explored through non-targeted metabonomics, electrophysiological experiment and molecular level docking. The results showed that B. animalis F1-7 effectively alleviates OIC and promotes the expression of chromogranin A (CGA) and 5-hydroxytryptamine (5-HT). The metabolite 13,14-dihydro-15-keto-PGE2 related to B. animalis F1-7 is found, which has a potential improvement effect on OIC at 20 mg kg BW-1 in vivo. At 30 ng mL-1 it effectively stimulates secretion of CGA/5-HT (408.95 ± 1.18 ng mL-1 ) by PC-12 cells and changes the membrane potential potassium ion current without affecting the sodium ion current in vitro. It upregulates the target of free fatty acid receptor-4 protein(FFAR4/ß-actin, 0.81 ± 0.02). CONCLUSION: The results demonstrate that metabolite 13,14-dihydro-15-keto-PGE2 participated in B. animalis F1-7 to alleviate OIC via the 5-HT pathway.

The Effect of Nanoscale Modification of Nisin by Different Milk-Derived Proteins on Its Physicochemical Properties and Antibacterial Activity.

Nisin is used as a natural food preservative because of its broad-spectrum antimicrobial activity against Gram-positive bacteria. However, free nisin is susceptible to various factors that reduce its antimicrobial activity. Milk protein, a protein derived from milk, has self-assembly properties and is a good carrier of bioactive substances. In this study, lactoferrin-nisin nanoparticles (L-N), bovine serum albumin-nisin nanoparticles (B-N), and casein-nisin nanoparticles (C-N) were successfully prepared by a self-assembly technique, and then their properties were investigated. The studies revealed that lactoferrin (LF) and nisin formed L-N mainly through hydrophobic interactions and hydrogen bonding, and L-N had the best performance. The small particle size (29.83 ± 2.42 nm), dense reticular structure, and good thermal stability, storage stability, and emulsification of L-N laid a certain foundation for its application in food. Further bacteriostatic studies showed that L-N enhanced the bacteriostatic activity of nisin, with prominent inhibitory properties against Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus, which mainly disrupted the cell membrane of the bacteria. The above results broaden our understanding of milk protein-nisin nanoparticles, while the excellent antibacterial activity of L-N makes it promising for application as a novel food preservative, which will help to improve the bioavailability of nisin in food systems.

Preparation and synbiotic interaction mechanism of microcapsules of Bifidobacterium animalis F1-7 and human milk oligosaccharides (HMO).

Probiotics such as Bifidobacterium spp. generally possess important physiological functions. However, maintaining probiotic viability is a challenge during processing, storage, and digestive transit period. Microencapsulation is widely considered to be an attractive approach. In this study, B. animalis F1-7 microcapsules and B. animalis F1-7-HMO microcapsules were successfully prepared by emulsification/internal gelation with high encapsulation efficiency (90.67 % and 92.16 %, respectively). The current study revealed that HMO-supplemented microcapsules exhibited more stable lyophilized forms and thermal stability. Additionally, a significant improvement in probiotic cell viability was observed in such microcapsules during simulated gastrointestinal (GI) fluids or storage. We also showed that the individual HMO mixtures 6'-SL remarkably promoted the growth and acetate yield of B. animalis F1-7 for 48 h (p < 0.05). The synbiotic combination of 6'-SL with B. animalis F1-7 enhanced SCFAs production in vitro fecal fermentation, decreasing several harmful intestinal bacteria such as Dorea, Escherichia-Shigella, and Streptococcus while enriching the probiotic A. muciniphila. This study provides strong support for HMO or 6'-SL combined with B. animalis F1-7 as an innovative dietary ingredient to bring health benefits. The potential of the synbiotic microcapsules with this combination merits further exploration for future use in the food industry.

New Horizons of Covalent Complex of Plant-Derived Recombinant Human Lactoferrin (OsrhLF) Combined with Different Polyphenols: Formation, Physicochemical Properties, and Gastrointestinal Fate.

Four typical dietary polyphenols ((-)-epigallocatechin gallate (EGCG), quinic acid (QA), caffeic acid (CA), and ferulic acid (FA)) were covalently prepared with rice recombinant human lactoferrin (OsrhLF) and bovine lactoferrin (bLF), and their structure and physicochemical properties were investigated, different lycopene emulsions were made by ultrasonic emulsification to analyze gastrointestinal fate. The results indicated that the covalent modification polyphenols changed the secondary/tertiary structure of LF, significantly improving the surface hydrophilicity, thermal stability, and antioxidant activity of LF. Compared with the bLF group, the OsrhLF group was more hydrophilic and the thermal denaturation temperature of the OsrhLF-CA reached 104.4 °C. LF-polyphenol emulsions significantly enhanced the photochemical stability and bioavailability of lycopene and achieved effective encapsulation and protection of lycopene compared to free lycopene, and the OsrhLF-EGCG reached 58.94% lycopene bioavailability. In short, OsrhLF does not differ much from bLF in terms of physicochemical properties and has a strong potential in the field of dietary supplements.

Metal-organic framework template-guided electrochemical lithography on substrates for SERS sensing applications.

The templating method holds great promise for fabricating surface nanopatterns. To enhance the manufacturing capabilities of complex surface nanopatterns, it is important to explore new modes of the templates beyond their conventional masking and molding modes. Here, we employed the metal-organic framework (MOF) microparticles assembled monolayer films as templates for metal electrodeposition and revealed a previously unidentified guiding growth mode enabling the precise growth of metallic films exclusively underneath the MOF microparticles. The guiding growth mode was induced by the fast ion transportation within the nanochannels of the MOF templates. The MOF template could be repeatedly used, allowing for the creation of identical metallic surface nanopatterns for multiple times on different substrates. The MOF template-guided electrochemical growth mode provided a robust route towards cost-effective fabrication of complex metallic surface nanopatterns with promising applications in metamaterials, plasmonics, and surface-enhanced Raman spectroscopy (SERS) sensing fields.

Bifidobacterium animalis sup F1-7 Acts as an Effective Activator to Regulate Immune Response Via Casepase-3 and Bak of FAS/CD95 Pathway.

Intestinal microecology was closely related to immune regulation, but the related mechanism was still unclear. This study aimed to reveal how microorganisms improved immune response via casepase-3 and Bak of FAS/CD95 pathway. Bifidobacterium animalis F1-7 inhibited the melanoma B16-F10 cells in vitro effectively; had a potent anticancer effect of lung cancer mice; effectively improved the spleen immune index and CD3+ (75.8%) and CD8+ (19.8%) expression level; strengthened the phagocytosis of macrophages; inhibited the overexpression of inflammatory factors IL-6 (319.10 ± 2.46 pg/mL), IL-8 (383.05 ± 9.87 pg/mL), and TNF-α (2003.40 ± 11.42 pg/mL); and promoted the expression of anti-inflammatory factor IL-10 (406.00 ± 3.59 pg/mL). This process was achieved by promoting caspase-8/3 and BH3-interacting domain death agonist (Bid), Bak genes, and protein expression. This study confirmed the B. animalis F1-7 could act as an effective activator to regulate immune response by promoting the expression of caspase-8/3, Bid and Bak genes, and proteins and by activating the FAS/CD95 pathway. Our study provided a data support for the application of potentially beneficial microorganisms of B. animalis F1-7 as an effective activator to improve immunity.

A visual colorimetric assay based on phage T156 and gold nanoparticles for the sensitive detection of Salmonella in lettuce.

In this study, a new technique was developed for visual and precise identification of Salmonella using phage T156-mediated aggregation of gold nanoparticles. The phage binds to gold nanoparticles in a dispersed and stable state under high NaCl concentrations. When Salmonella is introduced, the phage specifically recognizes and adsorbs the targeted bacteria, causing the AuNPs to undergo a discoloration reaction resulting in aggregation, which enables Salmonella visualization. The method has a detection range of 3.8 × 101-3.8 × 109 CFU/mL and a limit of detection of 38 CFU/mL and can produce results in approximately 80 min. The technique was also tested on field samples, including spiked lettuce, and was found to be accurate with a recovery rate of 81.0-119.2% and relative standard deviations ranging from 3.3% to 14.7%. Notably, this technique utilizes phages as recognition elements in colorimetric methods, offering simplicity, speed, and the ability to effectively distinguish between live and dead Salmonella. It demonstrates remarkable sensitivity, specificity, and accuracy. Furthermore, it presents a novel avenue for the rapid detection of other pathogenic bacteria.

Bifidobacterium bifidum Ameliorates DSS-Induced Colitis in Mice by Regulating AHR/NRF2/NLRP3 Inflammasome Pathways through Indole-3-lactic Acid Production.

In this study, the effectors and mechanisms of Bifidobacterium bifidum FL-276.1 and B. bifidum FL-228.1 in alleviating dextran sulfate sodium (DSS)-induced colitis were investigated. Both FL-276.1 and FL-228.1 significantly alleviated DSS-induced colitis, whether they were supplemented from the beginning of the experiment (whole course intervention) or after the DSS induction started (partial intervention). Aryl hydrocarbon receptor (AHR) and the nuclear factor erythroid 2-related factor 2 (NRF2) pathways were activated in mice colons, while the NLR family pyrin domain containing 3 (NLRP3) was downregulated under the whole course intervention modes. Indole-3-lactic acid, an AHR ligand produced by FL-276.1 and FL-228.1, could regulate the AHR/NRF2/NLRP3 pathway in Caco-2 monolayers, thus upregulating the tight junction proteins and protecting the integrity of the epithelial barrier. These results are conducive to promoting clinical trials and product development of probiotics for alleviating colitis.

Glycosylation reduces the allergenicity of turbot (Scophthalmus maximus) parvalbumin by regulating digestibility, cellular mediators release and Th1/Th2 immunobalance.

With turbot being increasingly consumed, turbot parvalbumin (TPV) allergy has become a pressing problem requiring immediate resolution. Glycosylation treatment not only resulted in cross-link formation but also caused changes in the simulated gastric fluid and simulated intestinal fluid digestion stability of TPV. In addition, KU812 experimentation revealed lower levels of ß-hexosaminidase, histamine, tryptase, interleukin 4 (IL-4)/IL-13 in glycated protein-treated mice compared with native PV-treated ones. Glycated TPV exhibited a weaker allergic reaction compared with native TPV. Systemic anaphylaxis resulted in mild anaphylactic responses and reduced temperature, along with significantly increased levels of immunoglobulin E and histamine. Furthermore, glycosylation treatment reduced the release of cellular mediators and cytokines (IL-4/IL-13). Glycation to T-PV decreased allergic responses by downregulating Th2 cytokines, regulated the Th1/Th2 balance and effectively reduce the allergenicity and sensitisation ability of T-PV.

Comparative Analysis of Glycosylation Affecting Sensitization by Regulating the Cross-Reactivity of Parvalbumins in Turbot (Scophthalmus maximus), Conger Eel (Conger myriaster) and Sea Bass (Micropterus salmoides).

Parvalbumin (PV) is the most common allergen in fish. Some patients with fish allergy are allergic to only one species of fish but are tolerant to others; however, the underlying mechanism has not been identified. This study showed that three types of glycated fishes' PV showed a similar decrease in immunoglobulin E (IgE) binding. Glycosylation could improve the simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) digestion resistance of fishes' PV. We also discovered that the cross-reactivity between eel and turbot was weaker than that of bass; glycosylation can reduce cross-reactivity between eel/bass and turbot by downregulating Th2 cytokines and upregulating Th1 cytokines as well as downregulating the expression of G-T PV, G-E PV, G-B PV of IL-4 (94.31 ± 3.16, 73.26 ± 0.91, 94.95 ± 3.03 ng/mL), and IL-13 (38.84 ± 0.75, 33.77 ± 0.71, 36.51 ± 0.50 ng/mL) and upregulating the expression of IFN-γ (318.01 ± 3.46, 387.15 ± 3.30, 318.01 ± 4.21 ng/mL) compared with T PV, respectively. This study showed that glycosylation affected sensitization by regulating the cross-reactivity of parvalbumins.

Fish allergens of turbot (Scophthalmus maximus) parvalbumin triggers food allergy via inducing maturation of bone marrow derived dendritic cells and driving Th2 immune response.

Aquatic food allergy has become a key food safety problem and therefore it is urgent to study the mechanism of aquatic food allergy. Turbot parvalbumin (PV) is a major marine food allergen that could cause allergic reactions but the cellular and molecular mechanisms remain to be defined. In this study, we used flow cytometry and ELISA, a coupled co-culture system of dendritic cells and T cells, and revealed that PV could promote the maturation of dendritic cells, mainly by inducing bone marrow-derived dendritic cells (BMDCs) to express MHC II and CD86, and promote the cytokines/chemokines IL-6, IFN-γ, IL-23, and IL-12p70, whereas inhibiting TNF-α expression. Our results suggested that murine BMDCs play a crucial role in the effect of PV on the induction of Th2 responses.

Mechanisms underlying the promotion of 5-hydroxytryptamine secretion in enterochromaffin cells of constipation mice by Bifidobacterium and Lactobacillus.

BACKGROUND: 5-Hydroxytryptamine (5-HT) could play a role in alleviating symptoms in constipation. However, the mechanism underlying the role of intestinal flora in the promotion of 5-HT secretion by enterochromaffin cells (ECs) and regulation of the gastrointestinal endocrine system remains unclear. METHODS: A constipation mouse model was constructed, and the 5-HT, chromogranin A (CGA), substance P (SP), motilin (MTL), dopamine, and noradrenaline expression levels were measured using enzyme-linked immunosorbent assay(Elisa) and immunofluorescence, and key proteins, such as the transient receptor potential (TRP) ion channels/tryptophan hydroxylase (TPH) and olfactory receptor (OR), were determined using western blot. Flow cytometry and in vivo imaging were used to observe microbial colonization in the intestinal tracts of mice. KEY RESULTS: Bifidobacterium animalis F1-7 (F1-7), Lactobacillus paraccasei F34-3 (F34-3), and Lactobacillus plantarum FWDG (FWDG) promoted 5-HT secretion. F1-7 and F34-3 induced CGA expression, increased catecholamine secretion, and activated the CGA/α2A adrenoreceptor (ADRα2A) cascade signal in ECs. FWDG increased noradrenaline levels and activated the ADRα2A signal in ECs. SP content increased in F1-7 and F34-3, and MTL expression increased in FWDG via the above signal. F1-7 and F34-3 downregulated TRPV4 and upregulated TPH, whereas FWDG upregulated OR2A4 for promoting 5-HT secretion by ECs. Finally, we observed that F1-7, F34-3, and FWDG were well colonized in the large intestine. CONCLUSIONS AND INFERENCES: F1-7, F34-3, and FWDG promoted 5-HT secretion in ECs of constipation mice by activating the CGA/ADRα2A cascade signal and regulating the TRP/TPH-OR pathways.

Bifidobacterium animalis F1-7 in combination with konjac glucomannan improves constipation in mice via humoral transport.

Probiotics and natural products can promote humoral transport and effectively relieve intestinal motility. This study investigated the effects of probiotics in combination with konjac glucomannan (KGM) and an aqueous extract of Prunus persica on constipation. The growth promotion effect of these natural products on probiotics was investigated using co-culture in vitro. The combined effect of probiotics and natural products on constipation was observed in mice. The tryptophan, tryptamine and short-chain fatty acid levels were determined using enzyme-linked immunosorbent assay, reverse-phase high-performance liquid chromatography, and gas chromatography. The key genes and proteins involved in humoral transport were identified using real-time polymerase chain reaction, western blotting and fluorescence immunoassay. KGM promoted the growth of Bifidobacterium animalis F1-7 in vitro, and a mixture of KGM and B. animalis F1-7 effectively promoted defaecation in mice, increased the faecal water content, shortened the defaecation time and improved the gastrointestinal transit rate. In mice, the KGM + F1-7 mixture reduced the tryptophan level and increased the levels of tryptamine, acetic acid, propionic acid, butyric acid and valeric acid. In addition, the KGM + F1-7 mixture effectively increased the mRNA level of 5-HT4-G-protein-coupled receptors (5-HT4GPCR)/mucins-2 (MUC-2) and reduced the level of aquaporins (AQP3); furthermore, it upregulated the protein level of 5-HT4GPCR/MUC-2 and downregulated the protein level of AQP3. These findings indicated that the KGM + F1-7 mixture effectively improved intestinal motility and alleviated constipation through humoral transport-related pathways.

Konjac glucomannan with probiotics acts as a combination laxative to relieve constipation in mice by increasing short-chain fatty acid metabolism and 5-hydroxytryptamine hormone release.

OBJECTIVES: Various probiotics and natural products can help to relieve constipation. This study aimed to explore the constipation-relieving effects and potential mechanism of a combination laxative of konjac glucomannan and probiotics. METHODS: This study evaluated the gastrointestinal-tract viability of probiotics in vitro. A constipation model was constructed in BALB/c mice, and the efficacies of the combinations verified in terms of their bowel movement-promoting effects, including the first black-stool defecation time and gastrointestinal transit rates of mice. Colonization by the probiotics was determined by quantitative real-time polymerase chain reaction. Hematoxylin-eosin staining, gas chromatography, enzyme-linked immunosorbent assay, quantitative real-time polymerase chain reaction, and Western blot were also used for analysis. RESULTS: Lactobacillus paracasei X11 (X11) and L. casei YRL577 (YRL577) had outstanding gastrointestinal-tract viability. Konjac glucomannan (KGM) + X11, Prunus persica + X11, and Prunus persica + YRL577 significantly relieved constipation. In addition, KGM promoted the colonization of X11. Meanwhile, KGM + X11 effectively promoted the metabolism of short-chain fatty acids in mice better than other combinations, and the 5-hydroxytryptamine (5-HT) content in the KGM + X11 group was the highest among all the groups. Therefore, KGM + X11 was selected for further research. The combination laxative promoted the secretion of 5-HT, up-regulated mRNA and protein levels of 5-HT receptor 4 and serotonin transporter via the 5-HT pathway, and effectively relieved constipation. CONCLUSIONS: The combination laxative konjac glucomannan-probiotic (KGM + X11) promoted defecation in constipated mice, possibly by increasing short-chain fatty acid metabolism and 5-HT hormone release.

The edible Lactobacillus paracasei X11 with Konjac glucomannan promotes intestinal motility in zebrafish.

BACKGROUND: Constipation is a gastrointestinal symptom with high incidence rate and large number of patients. It is becoming one of the urgent medical problems. Poor intestinal motility is one of the important causes of constipation. Current drug treatments for constipation are associated with many side effects; thus, it is necessary to study more effective treatment methods and potential mechanism. METHODS: A zebrafish model of intestinal motility obstruction was established by loperamide hydrochloride to evaluate the effect of probiotic, food ingredients, and combination on intestinal peristalsis according to intestinal peristalsis frequency counts. The gastrointestinal survival ability of the best probiotics was evaluated by surface hydrophobicity, self-aggregation, acid and bile salt tolerance, and gastrointestinal transit tolerance. Interactions between probiotics and food ingredients were studied in vivo and in vitro. The expression of 5-HT was detected by ELISA and fluorescence immunoassay, and 5-HT related genes were detected by RT-PCR. KEY RESULTS: We obtained the probiotics, food ingredients, and combination that effectively promoted intestinal peristalsis, X11 and YRL577, P. persica and KGM, KGM + X11, respectively. Both KGM and P. persica promoted colonization of probiotics in vivo. KGM + X11 could effectively promote the increase in 5-HT synthesis in zebrafish via up-regulating gene expression of TPH-1, TPH-2, and 5-HTR and down-regulating gene expression of SERT. The specific in-depth mechanism needs further study. CONCLUSIONS AND INFERENCES: The combinations of KGM with X11 effectively promoted intestinal peristalsis. We provide a theoretical basis for new modalities that can promote intestinal peristalsis and alleviate constipation.

Probiotics improved hyperlipidemia in mice induced by a high cholesterol diet via downregulating FXR.

Probiotics effectively regulated lipid metabolism and improved hyperlipidemia. The purpose of this study was to further evaluate the functions of lipid-lowering strains in vivo and elucidate the mechanism. The hyperlipidemia model was constructed using a high fat diet, and four lipid-lowering strains were selected for intervention. In the four strains, the strains Lactobacillus vaginalis FN3 (FN3) and Bifidobacterium animalis subsp. Lactis F1-7 (F1-7) reduced TG, TC and LDL and increased HDL. These two strains decreased TC and TC in the liver of high fat diet fed mice, and they increased total bile acids (TBA) in feces. F1-7 and FN3 reduced the mRNA levels of Farnesoid X Receptor (FXR), recombinant Fibroblast Growth Factor 15 (FGF 15) and Niemann-Pick C1-Like 1 (NPC1L1), and up-regulated the Liver X Receptor (LXR) mRNA level. They decreased the protein expressions of FXR and NPC1L1. In addition, F1-7 up-regulated the protein expression of cholesterol 7-alpha hydroxylase (CYP7A1). In summary, Bifidobacterium animalis subsp. Lactis F1-7 and Lactobacillus vaginalis FN3 could regulate bile acid metabolism by downregulating the FXR gene and reduce the absorption of exogenous cholesterol by regulating NPC1L1. F1-7 could also participate in the FXR/FGF15 pathway to improve hyperlipidemia, which showed better effects than FN3.

Screening of intestinal peristalsis-promoting probiotics based on a zebrafish model.

Based on the difference of the intestinal tract fluorescence intensity of zebrafish, the precise screening of strains with high retention capacity in vivo was completed and probiotics for intestinal peristalsis were quickly screened from strains with high retention capacity using the transparent visibility of zebrafish. In order to study the relationship between probiotic retention and intestinal peristalsis and develop constipation-resistant probiotics, this study used 2 types of strain and 6 potential functional strains and screened them based on the fluorescence intensity and intestinal peristalsis-promoting in the zebrafish model. The methods and results were as follows: (1) the zebrafish were immersed in the strains labeled with fluorescein isothiocyanate (FITC), and the intestinal fluorescence intensity was taken as the index. The strain L. paracasei X11 with good retention capacity was screened out. (2) 220 zebrafish were randomly selected and divided into 11 groups with 20 tails in each group. 1 group was the normal control group and the other 10 groups were used to construct the constipation zebrafish model by the loperamide hydrochloride method, namely, 1 model control group, 1 model + positive drug control group (domperidone), 2 model + type strains control groups, and 6 model + potential strain treatment groups. The intestinal peristalsis frequency of each group within 1 min was calculated after immersing the model zebrafish in 108 CFU mL-1 strain solution. The results showed that L. paracasei X11 had a better function of intestinal peristalsis-promotion.

Study of gastrointestinal tract viability and motility via modulation of serotonin in a zebrafish model by probiotics.

The relationship between bacterial strains and serotonin regulation was studied via the in vitro screening of the strains. Using the transparent visibility of zebrafish, the strains for intestinal peristalsis were quickly screened. The methods and results were as follows: (1) 18 strains with outstanding gastrointestinal viability via their surface hydrophobicity, self-aggregation ability, acid tolerance, bile tolerance, simulated gastric digestion and intestinal fluid tolerance were determined from 54 unpublished strains. (2) 5dpf zebrafish were randomly selected and divided into 22 groups with 12 tails in each group. The intestinal peristalsis frequency of each group within 1 min was calculated after immersing the model zebrafish in a 108 CFU mL-1 strain solution, with 5 effective strains obtained. (3) The serotonin in zebrafish was measured by Elisa and fluorescence immunization. The regulation mechanism of serotonin by Bifidobacterium animalis F1-7 was revealed by RT-PCR and the results show that this most effective strain promotes intestinal peristalsis in zebrafish via the modulation of serotonin release and key genes for serotonin synthesis in zebrafish.