Intestinal Probiotics Research Articles

Irritable bowel syndrome in children and intestinal microbiota: pathogenetic aspects and clinical guidelines

Irritable bowel syndrome (IBS) is one of the most common functional conditions among children and adults. At the basis of IBS, as well as other functional disorders of the digestive system, is the disorder of brain-gut-microbiota axis. In recent years, the latter has been given particular importance not only in post-infectious IBS, but also in classic stress-induced IBS. The intestinal microflora determines the state of the enteric nervous system, visceral sensitivity, intestinal motility. In addition, the intestinal microbiota interacts through the transmitters it produces with the central nervous system, which also affects intestinal motility and the state of the microflora. Updated guidelines for the diagnosis and treatment of IBS in children of the Russian Society of Pediatric Gastroenterologists, Hepatologists and Nutritionists in the treatment section include psychotherapeutic correction, diet therapy and drug therapy. Correctors of intestinal motility (trimebutine), probiotics and antispasmodics have proven effectiveness. The efficacy and safety of use in IBS in children Lactobacillus rhamnosus GG, L. acidophilus LA­5, B. infantis, B. animalis, L. plantarum, L. casei, L. bulgaricus, Bifidobacterium lactis BВ­12, B. breve, B. longum, S. thermophilus, Saccharomyces boulardii CNCM I­745. In this case, it is advisable to use multi-strain probiotics. Thus, the intestinal microbiota is directly involved in the pathogenesis of IBS, and the need for the use of probiotics as part of complex therapy is beyond doubt. Their effectiveness has been proven in many serious studies, which was the reason for their inclusion in practical recommendations for the treatment of IBS in children and adults.

Sodium alginate combined with oxymatrine ameliorates CCl4-induced chemical hepatic fibrosis in mice

Hepatic fibrosis (HF) is a challenging clinical problem. Both sodium alginate (SA) and oxymatrine (OM) can be used to treat HF; however, the influence of viscosity on the therapeutic efficacy of sodium alginate is currently unknown. This study used a CCl4-induced HF mouse model to screen the specifications and doses of SA and investigate its therapeutic effects on HF in combination with OM. Sodium alginate of different viscosities ameliorated HF in mice, with 232 mPa·s SA delivered at a dose of 100 mg/kg showing remarkable therapeutic effect, characterized by reduced aspartate transaminase/alanine transaminase levels, reduced expression of α-SMA, collagen I, and other related genes, and increased abundance of beneficial intestinal probiotics such as Lactococcus and Blautia. The combination treatment further improved other related indices and increased the abundance of Phascolarctobacterium and Oscillospiraceae. These results suggest that the oral administration of SA may improve HF via the “gut-liver axis” based on the gut microbiota and has potential clinical applications.

Preparation of lactosucrose catalyzed by levansucrase and evaluation of its prebiotic activity

Prebiotics play an important role in biological processes, which has stimulated great interest in their synthesis. This paper reports a levansucrase from Bacillus subtilis, demonstrating high catalytic selectivity for the synthesis of prebiotic lactosucrose with sucrose as a donor and lactose as an acceptor. The product was purified and the structure was characterized. The effects of lactosucrose on the proliferation and acid production of bifidobacterium and lactobacillus were better than that of lactulose and galactooligosaccharides(GOS). The short chain fatty acid (SCFA) content in the fermentation broth was also measured. It contains large amounts of SCFAs that act roles in intestinal homeostasis. The lactosucrose affected inflammatory responses in lipopolysaccharide-induced RAW 264.7 macrophages since they suppressed inflammatory cytokines TNF-α, IL-1β, and IL-6 well as compared to the control. Also, lactosucrose had no cytotoxicity in the concentration range of 10 mg/mL. These results indicate that lactosucrose was effective in promoting the proliferation of intestinal probiotics and have anti-inflammatory activity. Therefore, lactosucrose has positive prebiotic activity.

The effect of different prebiotics on intestinal probiotics in newly diagnosed diabetic patients.

Prebiotics exert favorable effects on the host through interactions with probiotics, and their beneficial impacts have been extensively validated across various chronic ailments, including diabetes. This study presents findings from a case-control investigation involving 10 individuals with type 2 diabetes mellitus (T2DM) and 10 healthy counterparts. Fresh stool specimens were collected from all participants. Following a 24-h fermentation period in mediums containing xylitol and mannitol, the observed increase in Lactobacillus abundance within the case group exceeded that of the control group. Similarly, in mediums containing soluble starch, choline, and L-carnitine, the augmentation of Bifidobacterium within the case group surpassed that of the controls. Notably, a statistically significant divergence in sugar degradation rate emerged between the case and control groups, specifically in the medium harboring lactulose and isomalto-oligosaccharides. Remarkably, the degradation rate of lactulose exhibited a positive correlation with the expansion of Bifidobacterium (R 2 = .147, p = .037). Likewise, the degradation rate of isomalto-oligosaccharides demonstrated a positive correlation with Bifidobacterium proliferation (R 2 = .165, p = .041). In conclusion, prebiotics like xylitol and mannitol exhibit the capacity to enhance intestinal probiotic populations in individuals newly diagnosed with diabetes. The modifications in the intestinal flora homeostasis of diabetic patients may be evidenced by alterations in the degradation rate of specific prebiotic substrates.

Synthesis of cello-oligosaccharides which promotes the growth of intestinal probiotics by multi-enzyme cascade reaction

Soluble cello-oligosaccharide with 2-6 oligosaccharide units is a kind of oligosaccharide with various biological functions, which can promote the proliferation of intestinal probiotics such as Bifidobacteria and Lactobacillus paracei. Therefore, it has a regulatory effect on human intestinal microbiota. In this study, a Cc 01 strain was constructed by expressing cellodextrin phosphorylase (CDP) in Escherichia coli. By combining with a previously constructed COS 01 strain, a three-enzyme cascade reaction system based on strains COS 01 and Cc 01 was developed, which can convert glucose and sucrose into cello-oligosaccharide. After optimization, the final titer of soluble cello-oligosaccharides with 2-6 oligosaccharide units reached 97 g/L, with a purity of about 97%. It contained cellobiose (16.8 wt%), cellotriose (49.8 wt%), cellotetrose (16.4 wt%), cellopentaose (11.5 wt%) and cellohexose (5.5 wt%). When using inulin, xylo-oligosaccharide and fructooligosaccharide as the control substrate, the biomass (OD600) of Lactobacillus casei (WSH 004), Lactobacillus paracei (WSH 005) and Lactobacillus acidophilus (WSH 006) on cello-oligosaccharides was about 2 folds higher than that of the control. This study demonstrated the efficient synthesis of cello-oligosaccharides by a three-enzyme cascade reaction and demonstrated that the synthesized cello-oligosaccharides was capable of promoting intestinal microbial proliferation.

Dihydromyricetin ameliorated nonalcoholic steatohepatitis in mice by regulating the composition of serous lipids, bile acids and ileal microflora

BackgroundDihydromyricetin (DMY) is a natural flavonoid with anti-nonalcoholic steatohepatitis (NASH) activity. However, the effects of DMY on the composition of lipids and bile acids (BAs) in serum, and gut microbiota (GM) in ileum of mice with NASH are not clear.MethodsAfter male C57BL/6 mice was fed with methionine and choline deficiency (MCD) diet and simultaneously administered with DMY (300 mg/kg/day) by gavage for 8 weeks, the pathological changes of liver tissue were observed by Oil Red O, hematoxylin eosin and Masson staining, the levels of serum alaninea minotransferase, aspartate aminotransferase and liver triglyceride, malonic dialdehyde were detected by the detection kits, the composition and contents of serum lipids and BAs were detected by Liquid Chromatograph-Mass Spectrometry, the mRNA levels of hepatic BAs homeostasis-related genes were detected by RT-qPCR, and microbiological diversity in ileum was analyzed by 16S rDNA sequencing.ResultsThe results showed that the significant changes including 29 lipids, 4 BAs (23-nor-deoxycholic acid, ursodeoxycholic acid, 7-ketodeoxycholic acid and cholic acid), 2 BA transporters (Mrp2 and Oatp1b2) and 8 GMs between MCD and DMY groups. Among them, DMY treatment significantly down-regulated 21 lipids, 4 BAs mentioned above, the ratio of Firmicutes/Bacteroidota and the abundance of Erysipelotrichaceae, Faecalibacuium, significantly up-regulated 8 lipids and 5 GMs (Verrucomicrobiota, Bacteroidota, Actinobacteria, Akkermansiaceae and Akkermansia).ConclusionsThe results suggested that DMY may alleviate MCD diet-induced NASH through decreasing the serum levels of toxic BAs which regulated by liver Oatp1b2 and Mrp2, regulating the metabolism of related lipids, and up-regulating intestinal probiotics (Actinobacteria and Verrucomicrobiota at the phylum level; Akkermansiaceae at the family level; Akkermansiaat at the genus level) and inhibiting intestinal harmful bacteria (Firmicutes at the phylum level; Erysipelotrichaceae at the family level; Faecalibaculum at the genus level).

High-protein compound yogurt with quinoa improved clinical features and metabolism of high-fat diet–induced nonalcoholic fatty liver disease in mice

Gut microbiota dysbiosis plays a crucial role in the occurrence and progression of nonalcoholic fatty liver disease (NAFLD), which may be influenced by nutritional supplementation. Quinoa, a type of pseudocereal, has gained prominence due to its high nutritional value and diverse applications. This study aimed to determine whether yogurt containing quinoa can ameliorate NAFLD and alleviate metabolic disorders by protecting against the divergence of gut microbiota. Our findings suggested that quinoa yogurt could significantly reduce the body weight gain and fat tissue weight of high-fat diet (HFD)-fed obese mice. In addition, quinoa yogurt significantly reduced liver steatosis and enhanced glucose homeostasis and insulin sensitivity. Additional research indicates that quinoa yogurt can reduce the levels of proinflammatory cytokines (i.e., tumor necrosis factor α, IL-1β, and IL-6) and inhibit endotoxemia and systemic inflammation. The characteristics of the gut microbiota were then determined by analyzing 16S rRNA. In addition, we discovered that the gut microbiota was disturbed by HFD consumption. Particularly, intestinal probiotics and beneficial intestinal secretions were increased, leading to the expression of glucagon-like peptide-1 in the colon, contributing to NAFLD. Furthermore, endotoxemia and systemic inflammation in HFD-fed mice were restored to the level of control mice when they were fed yogurt and quinoa. Therefore, yogurt containing quinoa can effectively alleviate NAFLD symptoms and may exert its effects via microbiome-gut-liver axis mechanisms. According to some research, the role of the enteric-liver axis may also influence metabolic disorders to reduce the development of NAFLD.

Effect of sturgeon protein in promoting the adhesion of Lactobacillus plantarum and Lactobacillus rhamnosus

Dietary protein could serve as primary nitrogen source for intestinal flora to enhance the intestinal environment by influencing probiotic adhesion. Our work aims to demonstrate a framework for probiotic activity guided isolation of potential effective fractions from the sturgeon protein. We confirmed the isolated fractions of sturgeon protein as having probiotic adhesion activity against Lactobacillus plantarum 45 (LP45) and Lactobacillus rhamnosus GG (LGG). Three protein fractions (0%, 40%, and 60% NaCl elution fractions) were obtained through anion exchange resin column. The molecular weights of the three fractions were identified by polyacrylamide gel electrophoresis in the ranges of 20.1–66.4 kDa (Fr1), 14.3–44.3 kDa (Fr2) and 14.3–97.2 kDa (Fr3), respectively. A detailed study was performed using an in vitro adhesion model to obtain the bioactive protein. In this model, probiotics were incubated on isolated intestinal segments of mice, and the adhesion effect of probiotics was evaluated through polysaccharide analysis, biofilm quantification, viable count measurement and electron microscopy. Notably, Fr2 was identified as the most effective fractions, significantly increasing the intestinal adhesion rates of LP45 and LGG by 144.8% and 53.7%, respectively. Ultimately, the primary structure of the protein 14.3 kDa in Fr2 was identified by mass spectrometry. Partial peptide amino acid sequences of the protein were confirmed to be W-W-Y-C-F (m/z = 804), K-N-H-D-I/L-Q-A-D-D-I/L-T-C (m/z = 1510) and Q-M-V-H-K-I/L-E-D-E-E-I/L-C-T-S-A-D-K-D (m/z = 2300). In conclusion, we found evidence that purified fractions of sturgeon protein facilitates the adhesion of intestinal probiotics and can be used as an active protein beneficial for intestinal health.

Establishment of CRISPR-Cas9 system in Bifidobacteria animalis AR668

Bifidobacteria are representative intestinal probiotics that have extremely high application value in the food and medical fields. However, the lack of molecular biology tools limits the research on functional genes and mechanisms of bifidobacteria. The application of an accurate and efficient CRISPR system to genome engineering can fill the gap in efficient genetic tools for bifidobacteria. In this study, CRISPR system of B. animalis AR668 was established, which successfully knocked out gene 0348 and gene 0208. The influence of different homology arms and fragments on the knockout effect of the system was explored. In addition, the inducible plasmid curing system of bifidobacteria was innovatively established. This study contributes to the genetic modification and functional mechanism analysis of bifidobacteria.

The improvement of intestinal dysbiosis and hepatic metabolic dysfunction in dextran sulfate sodium-induced colitis mice: effects of curcumin.

Curcumin may have promising application in the prevention and amelioration of inflammatory bowel disease (IBD). However, the underlying mechanisms underpinning the ability of curcumin to interact with the gut and liver in IBD remains to be defined, which is the exploration aim of this study. Mice with dextran sulfate sodium salt (DSS)-induced acute colitis were treated either with 100mg/kg of curcumin or phosphate buffer saline (PBS). Hematoxylin-eosin (HE) staining, 16S rDNA Miseq sequencing, proton nuclear magnetic resonance (1 H NMR) spectroscopy, and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were applied for analysis. Spearman's correlation coefficient (SCC) was utilized to assess the correlation between the modification of intestinal bacteria and hepatic metabolite parameters. Curcumin supplementation not only prevented further loss of body weight and colon length in IBD mice but also improved diseases activity index (DAI), colonic mucosal injury, and inflammatory infiltration. Meanwhile, curcumin restored the composition of the gut microbiota, significantly increased Akkermansia, Muribaculaceae_unclassified, and Muribaculum, and significantly elevated the concentration of propionate, butyrate, glycine, tryptophan, and betaine in the intestine. For hepatic metabolic disturbances, curcumin intervention altered 14 metabolites, including anthranilic acid and 8-amino-7-oxononanoate while enriching pathways related to the metabolism of bile acids, glucagon, amino acids, biotin, and butanoate. Furthermore, SCC analysis revealed a potential correlation between the upregulation of intestinal probiotics and alterations in liver metabolites. The therapeutic mechanism of curcumin against IBD mice occurs by improving intestinal dysbiosis and liver metabolism disorders, thus contributing to the stabilization of the gut-liver axis.

Probiotics and gut-skin axis - new look on factors affecting skin condition

Introduction and purpose 
 The human gut microbiota consists of trillions of microscopic organisms, mostly bacterias. They play a significant role in nutrient metabolism, maintenance of structural integrity of the gut mucosal barrier, immunomodulation and protection against pathogens. Many factors can influence the composition of the intestinal microbiota, for example antibiotics, diet or stress. These factors may lead to dysbiosis which causes activation of neurotransmitters. It can results in the entry of metabolites to the blood stream, systemic immune dysregulation and alteration of skin microbiota. The aim of the study was to review the literature and determine the effects of intestinal microbiota and probiotics in selected skin diseases and what is new - skin aging process. 
 State of knowledge 
 We analyzed numerous studies which indicate that disturbed gut microbiota can be related to some chronic diseases, including skin disorders such as atopic dermatitis, acne vulgaris, psoriasis and rosacea. Additionally, it has been proven that bacterial dysbiosis can intensify the skin aging proces. In order to reproduce normal gut microbiota probiotics are used. Despite the fact that there are only a few studies showing the unequivocal effect of probiotics on skin diseases, their results seem to be encouraging. 
 Conclusions 
 Proper composition of the intestinal microbiome determines the homeostasis of the human body. Disturbance of the gut microbiome play a significant role not only in development and aggravation of many skin diseases, but also have an impact on the skin aging. Despite quite a lot number of studies assessing the impact of microbiota on certain skin disorders, there is still a need to evaluate impact of probiotics. Researches indicate that they can be used as a helpful therapeutic tool. Taking this into account, it is worth considering it in the treatment process.

Comparative transcriptome and gut microbiota analysis of Exopalaemon carinicauda with different growth rates from a full-sib family

In the breeding process of Exopalaemon carinicauda from the same family, noticeable differences often occur in growth characteristics under the same conditions. To investigate this issue, we performed a comparative transcriptome analysis to identify the critical genes involved in weight gain and compared the intestinal flora to screen for potential intestinal probiotics. In total, we identified 1311 differentially expressed genes (DEGs), of which 735 genes, including troponin C, chitinase, cathepsin B, cathepsin L, and trypsin, were upregulated exclusively in the fast growth group. Several DEGs were validated by quantitative real-time PCR and assigned to the ribosome, phagosome, apoptosis, purine metabolism, and Hippo signaling pathways. The microbiome community richness and diversity of the fast-growing individuals (FGIs) were higher than those of the slow-growing individuals (SGIs). In the current study, the intestinal microflora was mainly distributed in the Proteobacteria, Firmicutes, and Bacteroidota. The species with significant differences (P < 0.05) between the FGI and SGI groups included the iron-reducing bacteria, Nitrospira moscoviensis, Sulfuritalea hydrogenivorans, and Alpha proteobacterium. Our results provided insights towards revealing the mechanism underlying the growth differences in E. carinicauda.

Tracking of Intestinal Probiotics In Vivo by NIR-IIb Fluorescence Imaging.

The ability to accurately characterize microorganism distribution in the intestinal tract is helpful for understanding intrinsic mechanisms. Within the intestine, traditional optical probes used for microorganism labeling commonly suffer from a low imaging penetration depth and poor resolution. We report a novel observation tool useful for microbial research by labeling near-infrared-IIb (NIR-IIb, 1500-1700 nm) lanthanide nanomaterials NaGdF4:Yb3+,Er3+@NaGdF4,Nd3+ (Er@Nd NPs) onto the surface of Lactobacillus bulgaricus (L. bulgaricus) via EDC-NHS chemistry. We monitor microorganisms in tissue by two-photon excitation (TPE) microscopy and in vivo with NIR-IIb imaging. This dual-technique approach offers great potential for determining the distribution of transplanted bacteria in the intestinal tract with a higher spatiotemporal resolution.

Relationship of environmental factors in pond water and dynamic changes of gut microbes of sea bass Lateolabrax japonicus.

The effect of structure of gut microbes on the health of host has attracted increasing attention. Sea bass Lateolabrax japonicus is an important farmed fish in China. The relationship of the dynamic changes of intestinal bacterial communities in L. japonicus and the cultural water environment is very important for healthy culture. Here, the diversity and abundance of the gut microbial communities of L. japonicus were evaluated during the culture using 16S rRNA Illumina sequencing. Both the opportunistic pathogens Aeromonas (1.68%), Vibrio (1.59%), and Acinetobacter (1.22%); and the potential probiotics Lactobacillus (2.27%), Bacillus (1.16%), and Lactococcus (0.37%) were distributed in the gut of L. japonicus. The increasing concentration of nitrogen of water environments with the increase of culture time significantly correlated with shifts in the microbial community structure: 40.04% of gut microbial changes due to nitrogen concentration. Higher concentrations of nitrogen showed a significantly negative correlation with intestinal probiotics in L. japonicus. The results indicate that the abundance of intestinal bacteria of L. japonicus is mainly driven by the changes of environmental factors (e.g., nitrogen), and it's very important that the linking environmental parameters with bacterial data of guts could be used as an early warning indicator in L. japonicus heath culture.

The lipid-lowering effects of fenugreek gum, hawthorn pectin, and burdock inulin.

The present study aimed to investigate the lipid-lowering effects and mechanisms of fenugreek gum (FG), hawthorn pectin (HP), and burdock inulin (BI) on high-fat diet (HFD)-induced hyperlipidemic rats. In this study, high-fat diet (HFD) together with fat emulsion administration were used to establish hyperlipidemia model. The biochemical indices were assayed after administration of FG, HP, and BI. Their effects were evaluated by factor analysis. Alterations of gut microbiota and short chain fatty acids (SCFAs) in the cecal were assessed to illustrate the mechanism of lipid lowering. The supplementation of FG, HP, and BI on HFD-fed rats decreased the levels of serum lipid and reduced the HFD-related liver and testicle damage. In the scatter plot of factor analysis, HP and BI were closer to normal fat diet (NFD) group in restoring the severity of hyperlipidemia, while FG and HP enhanced the excretion of cholesterol and bile acids (BAs). The levels of total SCFAs, especially butyric acid reduced by HFD were increased by HP. The ratio of Firmicutes to Bacteroidetes increased by HFD was reduced by HP and BI. FG, HP, and BI enriched intestinal probiotics, which were related to bile acid excretion or lipid-lowering. FG inhibited the absorption of cholesterol and enhanced the excretion of it, as well as increased the abundance of beneficial bacteria. While BI restored the imbalance of intestinal microbiota. HP enhanced the excretion of cholesterol and BAs, and restored the imbalance of intestinal microbiota. It was also utilized by intestinal microorganisms to yield SCFAs. This study suggested that FG, HP, and BI possessed the potential to be utilized as dietary supplements for obesity management.

Nutritional composition of fresh carcass of turbot fed with Bacillus subtilis SMF1, B. licheniformis LMF1 and B. siamensis DL3 and its relationship with intestinal flora

Bacillus is one of the most common probiotics used in aquaculture. This study revealed the effects of different Bacillus species on the digestive enzyme activities, intestinal flora, and flesh quality of turbot. Moreover, this study also indicated the correlations between the digestive enzyme activities, flesh quality and intestinal flora of turbot. Based on the purpose of this study, 96 healthy turbots were randomly divided into four experimental groups. Fish were fed by basal diet as control group (T0) and the basal diet supplemented by Bacillus subtilis SMF1, B. licheniformis LMF1 and B. siamensis DL3 were treaded as treatment group (B1), treatment group (B2), and treatment group (B3), respectively. The results showed that dietary supplementation with Bacillus sp. improved protease and lipase activities, the contents of total protein and fat of proximate carcass, and regulated the intestinal flora. It also affected the contents of certain amino acids, such as sulfur amino acids (SAAs). However, the effects of the dietary supplementation with Bacillus sp. on the contents of fresh and total essential amino acids were not significant. The dietaries with B. licheniformis LMF1 and B. siamensis DL3 promoted the increasing of the relative abundance of bacteria, such as unidentified_Clostridiales, unidentified_Enterobacteriaceae, and Romboutsia in the intestine. The promotions were related to the metabolism of sulfur compounds, which resulting in different SAAs in turbot carcass. Moreover, the dietary with B. subtilis SMF1 increased the contents of polyunsaturated fatty acids (PFAs) and docosahexaenoic acid (DHA) in the carcass of turbots. As the results showed, B. subtilis SMF1 significantly increased the relative abundances of Mycoplasma and Chryseobacterium in intestines of fish. The effects of the dietary with B. subtilis SMF1were positively related to PFAs or DHA levels. Meanwhile, Bacillus improved the nutritional composition of turbot carcass by promoting the probiotics in turbot intestine, such as Acinetobacter, Ralstonia, Lactobacillus, and Bifidobacterium, and reducing the relative abundance of the bacteria, such as Vibrio and Bacteroides in turbot intestine.

Positive and negative effects of recirculating aquaculture water advanced oxidation: O3 and O3/UV treatments improved water quality but increased antibiotic resistance genes

Recirculating aquaculture systems (RASs) can be efficiently used for aquaculture, and oxidation treatment is commonly used to improve water quality. However, the effects of oxidation treatments on aquaculture water safety and fish yield in RASs are poorly understood. In this study, we tested the effects of O3 and O3/UV treatments on aquaculture water quality and safety during culture of crucian carp. O3 and O3/UV treatments reduced the dissolved organic carbon (DOC) concentration by ∼40% and destroyed the refractory organic lignin-like features. There was enrichment of ammonia oxidizing (Nitrospira, Nitrosomonas, and Nitrosospira) and denitrifying (Pelomonas, Methyloversatilis, and Sphingomonas) bacteria, and N-cycling functional genes were enriched by 23% and 48%, respectively, after O3 and O3/UV treatments. Treatment with O3 and O3/UV reduced NH4+-N and NO2–-N in RASs. O3/UV treatment increased fish length and weight as well as probiotics in fish intestine. However, high saturated intermediates and tannin-like features induced antibiotic resistance genes (ARGs) in O3 and O3/UV treatments, by 52% and ∼28%, respectively, and also enhanced horizontal transfer of ARGs. Overall, the application of O3/UV achieved better effects. However, understanding the potential biological risks posed by ARGs in RASs and determining the most efficient water treatment strategies to mitigate these risks should be goals of future work.

Fish Probiotics: Cell Surface Properties of Fish Intestinal Lactobacilli and Escherichia coli

The properties of intestinal bacteria/probiotics, such as cell surface hydrophobicity (CSH), auto-aggregation, and biofilm formation ability, play an important role in shaping the relationship between the bacteria and the host. The current study aimed to investigate the cell surface properties of fish intestinal bacteria and probiotics. Microbial adhesion to hydrocarbons was tested according to Kos and coauthors. The aggregation abilities of the investigated strains were studied as described by Collado and coauthors. The ability of bacterial isolates to form a biofilm was determined by performing a qualitative analysis using crystal violet staining based on the attachment of bacteria to polystyrene. These studies prove that bacterial cell surface hydrophobicity (CSH) is associated with the growth medium, and the effect of the growth medium on CSH is species-specific and likely also strain-specific. Isolates of intestinal lactobacilli from fish (Salmo ischchan) differed from isolates of non-fish/shrimp origin in the relationship between auto-aggregation and biofilm formation. Average CSH levels for fish lactobacilli and E. coli might were lower compared to those of non-fish origin, which may affect the efficiency of non-fish probiotics use in fisheries due to the peculiarities of the hosts' aquatic lifestyles.

Efficient production of d-tagatose via DNA scaffold mediated oxidoreductases assembly in vivo from whey powder

Among the emerging sweeteners, d-tagatose occupies a significant niche due to its low calorific value, antidiabetic property and growth promoting effects on intestinal probiotics. Recently, the main approach for d-tagatose biosynthesis is l-arabinose isomerase-based isomerization reaction from galactose, which shows relatively low conversion rate because of unfavorable thermodynamic equilibria. Herein, oxidoreductases, d-xylose reductase and galactitol dehydrogenase, together with endogenous β-galactosidase were employed to catalyze the biosynthesis of d-tagatose from lactose with a yield of 0.282 g/g in Escherichia coli. Then, a deactivated CRISPR-associated (Cas) proteins-based DNA scaffold system was developed, which were proved to be efficient for assembling the oxidoreductases in vivo and got a 1.44-folds increase in d-tagatose titer and yield. Further, by employing d-xylose reductase with higher galactose affinity and activity, as well as overexpressing pntAB genes, the d-tagatose yield from lactose (0.484 g/g) increased to 92.0 % of the theoretical value, 1.72-times as that of original strain. Finally, whey powder, a lactose-rich food by-product, was bifunctionally utilized as an inducer and substrate. In the 5 L bioreactor, d-tagatose titer reached 32.3 g/L with little galactose detected, and the yield from lactose approached 0.402 g/g, which was the highest from waste biomass in the literature. The strategies used here might provide new insights into the biosynthesis of d-tagatose in future.

Effects of several flavonoids on human gut microbiota and its metabolism by in vitro simulated fermentation.

Flavonoids have antiviral, antitumor, anti-inflammatory, and other biological activities. They have high market value and are widely used in food and medicine fields. They also can regulate gut microbiota and promote human health. However, only a few flavonoids have been reported for their regulatory effects on human gut microbiota. The effects of hesperidin, hesperetin-7-O-glucoside, hesperetin, naringin, prunin, naringenin, rutin, isoquercitrin, and quercetin on gut microbiota structural and metabolic differences in healthy subjects were studied by means of in vitro simulated fermentation technology. Results showed that the nine kinds of flavonoids mentioned above, especially hesperetin-7-O-glucoside, prunin, and isoquercitrin, were found to have more effect on the structure of human gut microbiota, and they could significantly enhance Bifidobacterium (p < 0.05). After 24 h of in vitro simulated fermentation, the relative abundance of intestinal probiotics (e.g., Lactobacillus) was increased by the three flavonoids and rutin. Furthermore, the relative abundance of potential pathogenic bacteria was decreased by the addition of hesperetin-7-O-glucoside, naringin, prunin, rutin, and isoquercitrin (e.g., Lachnoclostridium and Bilophila). Notably, prunin could also markedly decrease the content of H2S, NH3, and short-chain fatty acids. This performance fully demonstrated its broad-spectrum antibacterial activity. This study demonstrates that flavonoids can regulate the imbalance of gut microbiota, and some differences in the regulatory effect are observed due to different structures. This work provides a theoretical basis for the wide application of flavonoids for food and medicine.