Label/immobilization-free Cas12a-based electrochemiluminescence biosensor for sensitive DNA detection.

Electrochemiluminescence (ECL) is one of the most sensitive techniques in the field of diagnostics. However, they typically require luminescent labeling and electrode surface biological modification, which is a time-consuming and laborious process involving multiple steps and may also lead to low reaction efficiency. Fabricating label/modification-free biosensors has become one of the most attractive parts for simplifying the ECL assays.

A MnO nanosheet-mediated CRISPR/Cas12a system for the detection of organophosphorus pesticides in environmental water.

Nowadays, easy, convenient, and sensitive sensing strategies are still critical for organophosphorus pesticides in environmental water samples. Herein, a novel organophosphorus pesticide (OP) assay based on acetylcholinesterase (AChE) and a MnO nanosheet-mediated CRISPR/Cas12a reaction is reported. The single-strand DNA (ssDNA) activator of CRISPR/Cas12a was simply adsorbed on the MnO nanosheets as the nanoswitches of the assay.

Cas12a-assisted RTF-EXPAR for accurate, rapid and simple detection of SARS-CoV-2 RNA.

Developing highly accurate and simple approaches to rapidly identify and isolate SARS-CoV-2 infected patients is important for the control of the COVID-19 pandemic. We, herein, reported the performance of a Cas12a-assisted RTF-EXPAR strategy for the identification of SARS-CoV-2 RNA. This assay combined the advantages of RTF-EXPAR with CRISPR-Cas12a can detect SARS-CoV-2 within 40 min, requiring only isothermal control.

Rapid and sensitive detection of Ebola RNA in an unamplified sample based on CRISPR-Cas13a and DNA roller machine.

A fast and simple Cas13a-based assay approach for direct detecting Ebola RNA in unamplified samples is reported. The procedure (named Cas-Roller) is comprised of a 10-min Cas13a-mediated cleavage protocol, followed by a DNA roller running for 30 min. This involves Cas13a collateral cleaving a suitably designed substrate in the presence of Ebola virus RNA sequence, and the cleavage product is used for DNA roller to amplify and generate fluorescent signals.

Exopolysaccharide produced by Streptococcus thermophiles S-3: Molecular, partial structural and rheological properties.

Yogurt fermented by Streptococcus thermophiles S-3 strain showed higher viscosity and thicker mouth feel than the ones using other lactic acid bacteria strains, which was due to the higher yield of exopolysaccharide (EPS-3) produced during fermentation process. In the present study, molecular characteristics, partial structural features and rheological properties of EPS-3 were studied using triple-detector HPSEC, NMR and steady & dynamic rheological testing, respectively. EPS-3 showed relatively high molecular weight (574 kDa) and narrow polydispersity Index (1.

Analysis of newly detected tetracycline resistance genes and their flanking sequences in human intestinal bifidobacteria.

Due to tetracycline abuse, the safe bifidobacteria in the human gastrointestinal intestinal tract (GIT) may serve as a reservoir of tetracycline resistance genes. In the present investigation of 92 bifidobacterial strains originating from the human GIT, tetracycline resistance in 29 strains was mediated by the tet(W), tet(O) or tet(S) gene, and this is the first report of tet(O)- and tet(S)-mediated tetracycline resistance in bifidobacteria. Antibiotic resistance genes harbored by bifidobacteria are transferred from other bacteria.

New genetic environments of the macrolide-lincosamide-streptogramin resistance determinant erm(X) and their influence on potential horizontal transferability in bifidobacteria.

With the abuse of macrolide, lincosamide, and streptogramin (MLS), the traditionally safe bifidobacterial strains in the human intestine could serve as a reservoir of MLS resistance genes. In this study, the erm(X) gene was detected in 29 MLS-resistant strains and one MLS-susceptible strain among 92 bifidobacterial strains of human origin. This study is the first to report erm(X)-mediated MLS resistance in Bifidobacterium pseudocatenulatum, Bifidobacterium breve and Bifidobacterium bifidum.

The Host Genotype and Environment Affect Strain Types of Bifidobacterium longum subsp. longum Inhabiting the Intestinal Tracts of Twins.

To investigate the influences of host genotype and environment on Bifidobacterium longum subsp. longum inhabiting human intestines at the strain level, six pairs of twins, divided into two groups (children and adults), were recruited. Each group consisted of two monozygotic (MZ) twin pairs and one dizygotic (DZ) twin pair.

Differences in acid tolerance between Bifidobacterium breve BB8 and its acid-resistant derivative B. breve BB8dpH, revealed by RNA-sequencing and physiological analysis.

Bifidobacteria are common inhabitants of the human gastrointestinal tract, and their application has increased dramatically in recent years due to their health-promoting effects. The ability of bifidobacteria to tolerate acidic environments is particularly important for their function as probiotics because they encounter such environments in food products and during passage through the gastrointestinal tract. In this study, we generated a derivative, Bifidobacterium breve BB8dpH, which displayed a stable, acid-resistant phenotype.

Relationship between acid tolerance and cell membrane in Bifidobacterium, revealed by comparative analysis of acid-resistant derivatives and their parental strains grown in medium with and without Tween 80.

The acid tolerance is particularly important for bifidobacteria to function as probiotics because they usually encounter acidic environments in food products and gastrointestinal tract passage. In this study, two acid-resistant derivatives Bifidobacterium longum JDY1017dpH and Bifidobacterium breve BB8dpH, which displayed a stable acid-resistant phenotype, were generated. The relationship between acid tolerance and cell membrane was investigated by comparing the two acid-resistant derivatives and their parental strains grown in medium with and without Tween 80.

Effect of Lactobacillus plantarum LP-Onlly on gut flora and colitis in interleukin-10 knockout mice.

Background And Aim: Probiotics are used in the therapy of inflammatory bowel disease. This study aimed to determine the effects of probiotic Lactobacillus plantarum LP-Onlly (LP) on gut flora and colitis in interleukin-10 knockout (IL-10(-/-) ) mice, a model of spontaneous colitis.

Methods: IL-10(-/-) and wild-type mice were used at 8 weeks of age and LP by gavage was administered at a dose of 10(9) cells/day per mice for 4 weeks.

Lactobacillus plantarum consumption increases PepT1-mediated amino acid absorption by enhancing protein kinase C activity in spontaneously colitic mice.

Although probiotic consumption has generally been shown to have many beneficial effects for the prevention and treatment of inflammatory bowel disease, the effects of Lactobacillus plantarum (LP) on intestinal nutrient absorption, particularly oligopeptide transporter 1 (PepT1)-mediated absorption of dietary protein under inflammatory conditions, has not yet been characterized. In this study, we first investigated the effects of LP consumption on plasma amino acid concentrations and PepT1-mediated absorption of cephalexin in the small intestine of wild-type (WT) mice and interleukin-10 knockout (IL-10(-/-)) mice, a model of spontaneous colitis. We then analyzed expression and distribution of PepT1 and protein kinase C (PKC) activity in the jejunum of these mice.

Lactobacillus plantarum ameliorates colonic epithelial barrier dysfunction by modulating the apical junctional complex and PepT1 in IL-10 knockout mice.

Probiotics are efficacious in the treatment of inflammatory bowel disease. However, the precise mechanisms remain unknown. To determine whether probiotic Lactobacillus plantarum (LP) ameliorates colonic epithelial barrier dysfunction present in interleukin-10 knockout (IL-10⁻(/)⁻) mice, IL-10⁻(/)⁻ and wild-type mice received LP or the vehicle for 4 wk.

L. plantarum prevents enteroinvasive Escherichia coli-induced tight junction proteins changes in intestinal epithelial cells.

Background: It is increasingly recognized that Lactobacillus plantarum (L. plantarum) has the ability to protect against Enteropathogenic Escherichia coli (EPEC)-induced damage of the epithelial monolayer barrier function by preventing changes in host cell morphology, attaching/effacing (A/E) lesion formation, monolayer resistance, and macromolecular permeability. However, the cellular mechanism involved in this protective effect still remained to be clarified.

Selection and optimization procedure of synbiotic for cholesterol removal.

A selection and optimization procedure for the synbiotic combination of probiotic and prebiotics was established to optimize its cholesterol removal in vitro. In light of fermentability, prebiotics utilization by probiotics was highly variable and interspecies differences existed. Based on the results of fermentability, L.

[An in vitro study of cholesterol-lowering properties of probiotics isolated from the human feces].

21 strains of Lactobacillus and Bifidobacterium, isolated from feces of healthy youth and children feces and identified by molecular biological methods, together with 6 strains of probiotics preserved in Onlly lab were studied in the experiments, including removal cholesterol from media, bile-tolerance and acid-tolerance. The results demonstrated that all strains could remove cholesterol from media and removal rates of 5 strains were more than 40%. Meanwhile these 5 strains had high removal effectiveness.

[Analysis of the probiotic Bifidobacterium and Lactobacillus community in child intestinal flora].

To investigate the distribution of child intestinal flora and the composition of its key probiotics community, study on intestinal flora of 21 Chinese children (age 2 - 5) was conducted, which included bacteria isolation and counting, 16S rDNA sequencing and homology analysis. For identification of the key probiotics such as Bifidobacterium and Lactobacillus in children feces at the species level, the specific primers Im26/Im3 and L159/L677 for PCR amplification of partial 16S rDNA were used. The results show that the composition of child intestinal flora is was relatively stable and almost same to the intestinal flora of the youth (age 20 - 25).

Effect of lactobacillus on the gut microflora and barrier function of the rats with abdominal infection.

Aim: To investigate the effect of probiotics supplemented by gut on the tight junctions of epithelial cells, barrier function and the microflora of rats with abdominal infection.

Methods: After the model of cecal ligation and perforation established, SD rats were divided into two groups: parenteral nutrition (PN) group and PN+probiotics (probiotics) group, PN solution was supplemented by neck vein and probiotics was delivered via the jejunostomy tube for five days. Vena cava blood and the homogenated tissue of liver, lung and mesenteric lymph nodes were cultured to determine the bacterial translocation rate (BTR).