Irisin attenuates ventilator-induced diaphragmatic dysfunction by inhibiting endoplasmic reticulum stress through activation of AMPK.

Mechanical ventilation (MV) is an essential life-saving technique, but prolonged MV can cause significant diaphragmatic dysfunction due to atrophy and decreased contractility of the diaphragm fibres, called ventilator-induced diaphragmatic dysfunction (VIDD). It is not clear about the mechanism of occurrence and prevention measures of VIDD. Irisin is a newly discovered muscle factor that regulates energy metabolism. Studies have shown that irisin can exhibit protective effects by downregulating endoplasmic reticulum (ER) stress in a variety of diseases; whether irisin plays a protective role in VIDD has not been reported. Sprague-Dawley rats were mechanically ventilated to construct a VIDD model, and intervention was performed by intravenous administration of irisin. Diaphragm contractility, degree of atrophy, cross-sectional areas (CSAs), ER stress markers, AMPK protein expression, oxidative stress indicators and apoptotic cell levels were measured at the end of the experiment.Our findings showed that as the duration of ventilation increased, the more severe the VIDD was, the degree of ER stress increased, and the expression of irisin decreased.ER stress may be one of the causes of VIDD. Intervention with irisin ameliorated VIDD by reducing the degree of ER stress, attenuating oxidative stress, and decreasing the apoptotic index. MV decreases the expression of phosphorylated AMPK in the diaphragm, whereas the use of irisin increases the expression of phosphorylated AMPK. Irisin may exert its protective effect by activating the phosphorylated AMPK pathway.

Rapid and sensitive lateral flow biosensor for the detection of GII human norovirus based on immunofluorescent nanomagnetic microspheres.

Human norovirus (HuNoV) is the most predominant viral agents of acute gastroenteritis. Point-of-care testing (POCT) based on lateral flow immunochromatography (LIFC) has become an important tool for rapid diagnosis of HuNoVs. However, low sensitivity and lack of quantitation are the bottlenecks of traditional LIFC. Thus, we established a rapid and accurate technique that combined immunomagnetic enrichment (IM) with LFIC to identify GII HuNoVs in fecal specimens. Before preparing immunofluorescent nanomagnetic microspheres and achieving the effect of HuNoV enrichment in IM and fluorescent signal in LFIC, amino-functionalized magnetic beads (MBs) and carboxylated quantum dots (QDs) were coupled at a mass ratio of 4:10. Anti-HuNoV monoclonal antibody was then conjugated with QDs-MB. The limit of detection was 1.56 × 104 copies/mL, and the quantitative detection range was 1.56 × 104 copies/mL-1 × 106 copies/mL under optimal circumstances. The common HuNoV genotypes GII.2, GII.3, GII.4, and GII.17 can be detected, there was no cross-reaction with various enteric viruses, including rotavirus, astrovirus, enterovirus, and sapovirus. A comparison between IM-LFIC and RT-qPCR for the detection of 87 fecal specimens showed a high level of agreement (kappa = 0.799). This suggested that the method is rapid and sensitive, making it a promising option for point-of-care testing in the future.

PECTIN METHYLESTERASE INHIBITOR18 functions in stomatal dynamics and stomatal dimension.

Pectin methylesterification in guard cell (GC) walls plays an important role in stomatal development and stomatal response to external stimuli, and pectin methylesterase inhibitors (PMEIs) modulate pectin methylesterification by inhibition of pectin methylesterase (PME). However, the function of PMEIs has not been reported in stomata. Here, we report the role of Arabidopsis (Arabidopsis thaliana) PECTIN METHYLESTERASE INHIBITOR18 in stomatal dynamic responses to environmental changes. PMEI18 mutation increased pectin demethylesterification and reduced pectin degradation, resulting in increased stomatal pore size, impaired stomatal dynamics, and hypersensitivity to drought stresses. In contrast, overexpression of PMEI18 reduced pectin demethylesterification and increased pectin degradation, causing more rapid stomatal dynamics. PMEI18 interacted with PME31 in plants, and in vitro enzymatic assays demonstrated that PMEI18 directly inhibits the PME activity of PME31 on pectins. Genetic interaction analyses suggested that PMEI18 modulates stomatal dynamics mainly through inhibition of PME31 on pectin methylesterification in cell walls. Our results provide insight into the molecular mechanism of the PMEI18-PME31 module in stomatal dynamics and highlight the role of PMEI18 and PME31 in stomatal dynamics through modulation of pectin methylesterification and distribution in GC walls.

Cold-tolerance mechanisms in foodborne pathogens: Escherichia coli and Listeria monocytogenes as examples.

The cold chain is an integral part of the modern food industry. Low temperatures can effectively alleviate food loss and the transmission of foodborne diseases caused by microbial reproduction. However, recent reports have highlighted shortcomings in the current cold chain technology's ability to prevent and control cold-tolerant foodborne pathogens. Furthermore, it has been observed that certain cold-chain foods have emerged as new sources of infection for foodborne disease outbreaks. Consequently, there is a pressing need to enhance control measures targeting cold-tolerant pathogens within the existing cold chain system. This paper aims to review the recent advancements in understanding the cold tolerance mechanisms of key model organisms, identify key issues in current research, and explore the potential of utilizing big data and omics technology in future studies.

Therapeutic applications of gut microbes in cardiometabolic diseases: current state and perspectives.

Cardiometabolic disease (CMD) encompasses a range of diseases such as hypertension, atherosclerosis, heart failure, obesity, and type 2 diabetes. Recent findings about CMD's interaction with gut microbiota have broadened our understanding of how diet and nutrition drive microbes to influence CMD. However, the translation of basic research into the clinic has not been smooth, and dietary nutrition and probiotic supplementation have yet to show significant evidence of the therapeutic benefits of CMD. In addition, the published reviews do not suggest the core microbiota or metabolite classes that influence CMD, and systematically elucidate the causal relationship between host disease phenotypes-microbiome. The aim of this review is to highlight the complex interaction of the gut microbiota and their metabolites with CMD progression and to further centralize and conceptualize the mechanisms of action between microbial and host disease phenotypes. We also discuss the potential of targeting modulations of gut microbes and metabolites as new targets for prevention and treatment of CMD, including the use of emerging technologies such as fecal microbiota transplantation and nanomedicine. KEY POINTS: • To highlight the complex interaction of the gut microbiota and their metabolites with CMD progression and to further centralize and conceptualize the mechanisms of action between microbial and host disease phenotypes. • We also discuss the potential of targeting modulations of gut microbes and metabolites as new targets for prevention and treatment of CMD, including the use of emerging technologies such as FMT and nanomedicine. • Our study provides insight into identification-specific microbiomes and metabolites involved in CMD, and microbial-host changes and physiological factors as disease phenotypes develop, which will help to map the microbiome individually and capture pathogenic mechanisms as a whole.

Skin microbiome profiling reveals the crucial role of microbial metabolites in anti-photoaging.

BACKGROUND: Skin microbiota is essential for health maintenance. Photoaging is the primary environmental factor that affects skin homeostasis, but whether it influences the skin microbiota remains unclear. OBJECTIVE: The objective of this study is to investigate the relationship between photoaging and skin microbiome. METHODS: A cohort of senior bus drivers was considered as a long-term unilateral ultraviolet (UV) irradiated population. 16S rRNA amplicon sequencing was conducted to assess skin microbial composition variations on different sides of their faces. The microbiome characteristics of the photoaged population were further examined by photoaging guinea pig models, and the correlations between microbial metabolites and aging-related cytokines were analyzed by high-throughput sequencing and reverse transcription polymerase chain reaction. RESULTS: Photoaging decreased the relative abundance of microorganisms including Georgenia and Thermobifida in human skin and downregulated the generation of skin microbe-derived antioxidative metabolites such as ectoin. In animal models, Lactobacillus and Streptobacillus abundance in both the epidermis and dermis dropped after UV irradiation, resulting in low levels of skin antioxidative molecules and leading to elevated expressions of the collagen degradation factors matrix metalloproteinase (MMP)-1 and MMP-2 and inflammatory factors such as interleukin (IL)-1ß and IL-6. CONCLUSIONS: Skin microbial characteristics have an impact in photoaging and the loss of microbe-derived antioxidative metabolites impairs skin cells and accelerates the aging process. Therefore, microbiome-based therapeutics may have potential in delaying skin aging.

Fatal Necrotizing Enterocolitis in Neonate Caused by Cronobacter sakazakii Sequence Type 64 Strain of CRISPR Sublineage b.

We report fatal neonatal necrotizing enterocolitis in China caused by Cronobacter sakazakii capsular profile K1:CA1, sequence type 64, and CRISPR type 197. Phylodynamic analyses indicated that the strain originated from the ancient, widespread, and antimicrobial drug-sensitive CRISPR sublineage b. Enhanced surveillance and pathogenesis research on this organism are required.

Semiquantitative Fingerprinting Based on Pseudotargeted Metabolomics and Deep Learning for the Identification of Listeria monocytogenes and Its Major Serotypes.

The rapid identification of pathogenic microorganism serotypes is still a bottleneck problem to be solved urgently. Compared with proteomics technology, metabolomics technology is directly related to phenotypes and has higher specificity in identifying pathogenic microorganism serotypes. Our study combines pseudotargeted metabolomics with deep learning techniques to obtain a new deep semiquantitative fingerprinting method for Listeria monocytogenes identification at the serotype levels. We prescreened 396 features with orthogonal partial least-squares discrimination analysis (OPLS-DA), and 200 features were selected for deep learning model building. A residual learning framework for L. monocytogenes identification was established. There were 256 convolutional filters in the initial convolution layer, and each hidden layer contained 128 filters. The total depth included seven layers, consisting of an initial convolution layer, a residual layer, and two final fully connected classification layers, with each residual layer containing four convolutional layers. In addition, transfer learning was used to predict new isolates that did not participate in model training to verify the method's feasibility. Finally, we achieved prediction accuracies of L. monocytogenes at the serotype level exceeding 99%. The prediction accuracy of the new strain validation set was greater than 97%, further demonstrating the feasibility of this method. Therefore, this technology will be a powerful tool for the rapid and accurate identification of pathogens.

Washed microbiota transplantation improves renal function in patients with renal dysfunction: a retrospective cohort study.

BACKGROUND: Changes in the gut microbiota composition is a hallmark of chronic kidney disease (CKD), and interventions targeting the gut microbiota present a potent approach for CKD treatment. This study aimed to evaluate the efficacy and safety of washed microbiota transplantation (WMT), a modified faecal microbiota transplantation method, on the renal activity of patients with renal dysfunction. METHODS: A comparative analysis of gut microbiota profiles was conducted in patients with renal dysfunction and healthy controls. Furthermore, the efficacy of WMT on renal parameters in patients with renal dysfunction was evaluated, and the changes in gut microbiota and urinary metabolites after WMT treatment were analysed. RESULTS: Principal coordinate analysis revealed a significant difference in microbial community structure between patients with renal dysfunction and healthy controls (P = 0.01). Patients with renal dysfunction who underwent WMT exhibited significant improvement in serum creatinine, estimated glomerular filtration rate, and blood urea nitrogen (all P < 0.05) compared with those who did not undergo WMT. The incidence of adverse events associated with WMT treatment was low (2.91%). After WMT, the Shannon index of gut microbiota and the abundance of several probiotic bacteria significantly increased in patients with renal dysfunction, aligning their gut microbiome profiles more closely with those of healthy donors (all P < 0.05). Additionally, the urine of patients after WMT demonstrated relatively higher levels of three toxic metabolites, namely hippuric acid, cinnamoylglycine, and indole (all P < 0.05). CONCLUSIONS: WMT is a safe and effective method for improving renal function in patients with renal dysfunction by modulating the gut microbiota and promoting toxic metabolite excretion.

GII.17[P17] and GII.8[P8] noroviruses showed different RdRp activities associated with their epidemic characteristics.

Norovirus is the primary foodborne pathogenic agent causing viral acute gastroenteritis. It possesses broad genetic diversity and the prevalence of different genotypes varies substantially. However, the differences in RNA-dependent RNA polymerase (RdRp) activity among different genotypes of noroviruses remain unclear. In this study, the molecular mechanism of RdRp activity difference between the epidemic strain GII.17[P17] and the non-epidemic strain GII.8[P8] was characterized. By evaluating the evolutionary history of RdRp sequences with Markov Chain Monte Carlo method, the evolution rate of GII.17[P17] variants was higher than that of GII.8[P8] variants (1.22 × 10-3 nucleotide substitutions/site/year to 9.31 × 10-4 nucleotide substitutions/site/year, respectively). The enzyme catalytic reaction demonstrated that the Vmax value of GII.17[P17] RdRp was 2.5 times than that of GII.8[P8] RdRp. And the Km of GII.17[P17] and GII.8[P8] RdRp were 0.01 and 0.15 mmol/L, respectively. Then, GII.8[P8] RdRp fragment mutants (A-F) were designed, among which GII.8[P8]-A/B containing the conserved motif G/F were found to have significant effects on improving RdRp activity. The Km values of GII.8[P8]-A/B reached 0.07 and 0.06 mmol/L, respectively. And their Vmax values were 1.34 times than that of GII.8[P8] RdRp. In summary, our results suggested that RdRp activities were correlated with their epidemic characteristics. These findings will ultimately provide a better understanding in replication mechanism of noroviruses and development of antiviral drugs.

Selenium-enriched foods and their ingredients: As intervention for the vicious cycle between autophagy and overloaded stress responses in Alzheimer's disease.

Dysfunctional autophagy induced by excessive reactive oxygen species (ROS) load and inflammation accelerates the development of Alzheimer's disease (AD). Recently, there has been an increasing interest in selenium-enriched ingredients (SEIs), such as selenoproteins, selenoamino acids and selenosugars, which could improve AD through antioxidant and anti-inflammation, as well as autophagy modulating effects. This review indicates that SEIs eliminate excessive ROS by activating the nuclear translocation of nuclear factor erythroid2-related factor 2 (Nrf2) and alleviate inflammation by inhibiting the mitogen-activated protein kinases (MAPKs)/nuclear factor kappa-B (NF-κB) pathway. Furthermore, they can activate the adenosine 5'-monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway, and subsequently promote amyloid beta (Aß) clearance and reduce memory impairments. SEIs are ubiquitous in many plants and microorganisms, such as Brassicaceae vegetables, yeast, and mushroom. Enzymatic hydrolysis, as well as physical processing, such as thermal, high pressure and microwave treatment, are the main techniques to modify the properties of dietary selenium. This work highlights the fact that SEIs can inhibit inflammation and oxidative stress and provides evidence that supports the potential use of these dietary materials to be a novel strategy for improving AD.

Gut microbiota: Candidates for a novel strategy for ameliorating sleep disorders.

The aim of this review was to evaluate the feasibility of treating sleep disorders using novel gut microbiota intervention strategies. Multiple factors can cause sleep disorders, including an imbalance in the gut microbiota. Studies of the microbiome-gut-brain axis have revealed bidirectional communication between the central nervous system and gut microbes, providing a more comprehensive understanding of mood and behavioral regulatory patterns. Changes in the gut microbiota and its metabolites can stimulate the endocrine, nervous, and immune systems, which regulate the release of neurotransmitters and alter the activity of the central nervous system, ultimately leading to sleep disorders. Here, we review the main factors affecting sleep, discuss possible pathways and molecular mechanisms of the interaction between sleep and the gut microbiota, and compare common gut microbiota intervention strategies aimed at improving sleep physiology.

Paenibacillus soyae sp. nov., isolated from the rhizosphere of soya bean.

A Gram-positive, facultatively anaerobic, agar-hydrolytic and rod-shaped bacterium with peritrichous flagellation, designated strain SCIV0701T, was isolated from soya bean rhizosphere soil collected from Bazhong, Sichuan Province, PR China and characterized by using polyphasic taxonomy. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SCIV0701T belonged to the genus Paenibacillus, and showed highest similarity to Paenibacillus nanensis MX2-3T (97.59 %), Paenibacillus paeoniae M4BSY-1T (97.45 %) and Paenibacillus pinisoli NB5T (97.45 %). The average nucleotide identity values and in silico DNA-DNA hybridization scores between strain SCIV0701T and P. nanensis MX2-3T, P. paeoniae M4BSY-1T and P. pinisoli NB5T were lower than recommended thresholds of 95% and 70 %, respectively, for species delineation. Menaquinone-7 was the predominant respiratory quinone. The polar lipids contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, two unidentified phospholipids and one unidentified aminophospholipid. The major fatty acids were anteiso-C15 : 0, C16 : 00 and iso-C16 : 0. Physiological and biochemical features differentiated strain SCIV0701T from the closely related Paenibacillus species. Based on the results of polyphasic taxonomic analysis, strain SCIV0701T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus soyae sp. nov. is proposed. The type strain is SCIV0701T (=GDMCC 1.2482T=JCM 34672T).

Spectroscopic Identification of the Dinitrogen Fixation and Activation by Metal Carbide Cluster Anions PtCn- (n = 4-6).

Nitrogen fixation is confronted with great challenges in the field of chemistry. Herein, we report that single metal carbides PtCn- and PtCnN2- (n = 4-6) are indispensable intermediates in the process of nitrogen fixation by mass spectrometry coupled with anionic photoelectron spectroscopy, quantum chemical calculations, and simulated density-of-state spectra. The most stable isomers of these cluster anions are characterized to have linear chain structures. The fixation and activation of dinitrogen are facilitated by the charge transfer from Pt and Cn to N2. The significance of π back-donation of the 5d orbital of the Pt atom to the antibonding π orbits of N2 for dinitrogen fixation and activation is discussed in detail. This study not only provides a theoretical basis at the molecular level for the activation of dinitrogen by mononuclear metal carbide clusters but also provides a new paradigm for dinitrogen fixation.

Effects of probiotics on hypertension.

Emerging data have suggested that probiotics had good potential in regulating intestinal flora and preventing hypertension. Some studies in human and animal models have demonstrated probiotic intervention could attenuate hypertension, regulate intestinal flora to increase the abundance of beneficial bacteria, and regulate intestinal microbial metabolites such as trimethylamine oxide, short-chain fatty acids, and polyphenols. However, there is still some debate as to whether probiotics exert effective benefits. These recently published reviews did not systematically expound on the heterogeneity between the effect and mechanism of probiotics with different types, doses, and carriers to exert antihypertensive effects, as well as the possible application of probiotics in the prevention and treatment of hypertension in food and clinic. Here we try to systematically review the association between hypertension and intestinal microflora, the effect of probiotics and their metabolites on hypertension, and the recent research progress on the specific mechanism of probiotics on hypertension. In addition, we also summarized the potential application of probiotics in antihypertension. Future challenges include elucidating the functions of metabolites produced by microorganisms and their downstream pathway or molecules, identifying specific strains, not just microbial communities, and developing therapeutic interventions that target hypertension by modulation of gut microbes and metabolites.

A systematic review and meta-analysis indicates a substantial burden of human noroviruses in shellfish worldwide, with GII.4 and GII.2 being the predominant genotypes.

Human noroviruses (HuNoVs) have been found as the leading cause of acute gastroenteritis outbreaks in all age groups and are significantly correlated with the consumption of shellfish. In this study, the contamination of HuNoVs in shellfish was estimated through a systematic review and meta-analysis. Studies on the contamination of HuNoVs in shellfish were searched from PubMed, Web of Science, Embase, and Cochrane Library from January 2000 to August 2021. A total of 75 studies were included, and the pooled HuNoVs prevalence in shellfish was 29% (95% CI: 23-35) worldwide. As revealed by the results of the subgroup meta-analysis, the prevalence of dominant genogroup was variable, and 4% (95% CI: 3-6), 13% (95% CI: 10-17), with 7% (95% CI: 4-11) of the samples, respectively, contaminated by GI alone, GII alone, and GI&GII. The HuNoVs prevalence of shellfish in Europe, America, and Asia was 33% (95% CI: 24-43), 24% (95% CI: 7-47), and 27% (95% CI: 18-35), respectively, while only 10% (95% CI: 5-17) in Africa. Furthermore, the prevalence of HuNoVs in shellfish was the highest in spring (35%, 95% CI: 23-49) and winter (35%, 95% CI: 22-50), and the lowest in summer (11%, 95% CI: 5-18). Oysters, clams, and mussels had comparable HuNoVs prevalence of 28% (95% CI: 20-37), 27% (95% CI: 16-39) and 24% (95% CI: 17-32), respectively. The prevalence of HuNoVs in shellfish from harvest areas and markets was 30% (95% CI: 23-38) and 30% (95% CI: 19-41), respectively. The results of this study suggest a substantial burden of HuNoVs in shellfish worldwide, with GII.4 (92.86%) and GII.2 (46.43%) as the predominant genotypes. This study provides information regarding the contamination of HuNoVs in shellfish worldwide, which will contribute to the development of appropriate control measures to prevent shellfish-related HuNoVs gastroenteritis.

Prevalence of antimicrobial resistance in a full-scale drinking water treatment plant.

Antibiotic resistance in drinking water has received increasing attention in recent years. In this study, the occurrence and abundance of antibiotic resistance genes (ARGs) in a drinking water treatment plant (DWTP) was comprehensively investigated using metagenomics. Bioinformatics analysis showed that 381 ARG subtypes belonging to 15 ARG types were detected, and bacitracin had the highest abundance (from 0.26 × 10-2 to 0.86 copies/cell), followed by multidrug (from 0.57 × 10-1 to 0.47 copies/cell) and sulfonamide (from 0.83 × 10-2 to 0.35 copies/cell). Additionally, 933 ARG-carrying contigs (ACCs) were obtained from the metagenomic data, among which 153 contigs were annotated as pathogens. The most abundant putative ARG host was Staphylococcus (7.9%), which most frequently carried multidrug ARGs (43.2%). Additionally, 38 high-quality metagenome-assembled genomes (MAGs) were recovered, one of which was identified as Staphylococcus aureus (Bin.624) and harboured the largest number of ARGs (n = 16). Using the cultivation technique, 60 isolates were obtained from DWTP samples, and Staphylococcus spp. (n = 11) were found to be dominant in all isolates, followed by Bacillus spp. (n = 17). Antimicrobial susceptibility testing showed that most Staphylococcus spp. were multidrug resistant (MDR). These results deepen our understanding of the distribution profiles of ARGs and antibiotic resistant bacteria (ARB) in DWTPs for potential health risk evaluation. Our study also highlights the need for new and efficient water purification technologies that can be introduced and applied in DWTPs.

Quantum Dots Tracking Endocytosis and Transport of Proteins Displayed by Mammalian Cells.

Mammalian cell display technology uses eukaryotic protein expression system to display proteins on cell surfaces and has become an important method in biological research. Although mammalian cell display technology has many advantages and development potential, certain attributes of the displayed protein remain uncharacterized, such as whether the displayed proteins re-enter the cell and how displayed proteins move into the cell. Here, we present the endocytosis mechanism, motility behavior, and transport kinetics of displayed proteins determined using HaloTag as the displayed protein and quantum dot-based single-particle tracking. The displayed protein enters the cell through clathrin-mediated endocytosis and is transported through the cell in three stages, which is dependent on microfilaments and microtubules. The dynamic information obtained in this study provides answers to questions about endocytosis and postendocytosis transport of displayed proteins and, therefore, is expected to facilitate the development of surface display technology.

Exploration of the molecular mechanisms underlying the antibiotic resistance of Helicobacter pylori: A whole-genome sequencing-based study in Southern China.

BACKGROUND: Although antimicrobial resistance (AMR) in Helicobacter pylori is a global threat to human health and the underlying molecular mechanisms have been explored previously, only a few of them are fully elucidated. MATERIALS AND METHODS: In the present study, we isolated 54 Helicobacter pylori strains from Southern China and assessed their susceptibility to five antibiotics using the agar dilution assay. Whole-genome sequencing was performed to screen the AMR genotypes of the Helicobacter pylori isolates. RESULTS: Our study revealed a high prevalence of resistance to clarithromycin (CLR), levofloxacin (LVX), and metronidazole (MTZ) in the Chinese isolates, 55.56% of which showed multidrug-resistant phenotypes. We screened for the 94 types of previously reported AMR mutations in 12 genes, but only a few of them were related to the AMR phenotype. Furthermore, we discovered four new mutations in the 23S rRNA gene and one mutation in infB related to CLR resistance. Another three mutations in gyrA and one in gyrB were closely correlated with the AMR pattern against LVX. We also demonstrated that the mutations R16C/H in rdxA, V56I in rpsU, and D54A in sodB might contribute to resistance to MTZ, which were previously reported in laboratory experiments but not found in clinical strains. We examined the concordance between the genotype and phenotype of AMR and identified several potential molecular biomarkers for predicting CLR and LVX resistance. CONCLUSIONS: Our study explored the molecular mechanisms underlying the antibiotic resistance of Helicobacter pylori isolates from Southern China. We propose further epidemiologic investigations in China.

Cloning, Expression, Purification, and Characterization of ß-Galactosidase from Bifidobacterium longum and Bifidobacterium pseudocatenulatum.

Expression and purification of ß-galactosidases derived from Bifidobacterium provide a new resource for efficient lactose hydrolysis and lactose intolerance alleviation. Here, we cloned and expressed two ß-galactosidases derived from Bifidobacterium. The optimal pH for BLGLB1 was 5.5, and the optimal temperature was 45 °C, at which the enzyme activity of BLGLB1 was higher than that of commercial enzyme E (300 ± 3.6 U/mg) under its optimal conditions, reaching 2200 ± 15 U/mg. The optimal pH and temperature for BPGLB1 were 6.0 and 45 °C, respectively, and the enzyme activity (0.58 ± 0.03 U/mg) under optimum conditions was significantly lower than that of BLGLB1. The structures of the two ß-galactosidase were similar, with all known key sites conserved. When o-nitrophenyl-ß-D-galactoside (oNPG) was used as an enzyme reaction substrate, the maximum reaction velocity (Vmax) for BLGLB1 and BPGLB1 was 3700 ± 100 U/mg and 1.1 ± 0.1 U/mg, respectively. The kinetic constant (Km) of BLGLB1 and BPGLB1 was 1.9 ± 0.1 and 1.3 ± 0.3 mmol/L, respectively. The respective catalytic constant (kcat) of BLGLB1 and BPGLB1 was 1700 ± 40 s-1 and 0.5 ± 0.02 s-1, respectively; the respective kcat/Km value of BLGLB1 and BPGLB1 was 870 L/(mmol∙s) and 0.36 L/(mmol∙s), respectively. The Km, kcat and Vmax values of BLGLB1 were superior to those of earlier reported ß-galactosidase derived from Bifidobacterium. Overall, BLGLB1 has potential application in the food industry.