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Background Although several systematic reviews and meta-analyses have been conducted to assess the relationship between fruit intake and health outcomes, the results of the relationship are inconclusive. Scope and approach We conducted an umbrella evaluation of existing research on the relationship between fruit intake and various health outcomes in humans. We used A Measurement Tool to Assess Systematic Reviews 2 and Grade of Recommendations, Assessment, Development and Evaluation to comprehensively evaluate the methodological quality and evidence quality of the research. We also performed a subgroup analysis based on the study design. Key findings and conclusions The umbrella review covered 59 qualified studies, which included 77 meta-analyses and 66 health outcomes. No adverse relationships between fruit intake and health outcomes were found. Moderate-quality evidence suggested that one serving increment of fruit per day could decrease the risks of cardiovascular disease (RR: 0.97, 95% CI: 0.95 to 0.99), stroke (RR: 0.92, 95% CI: 0.88 to 0.96), coronary heart disease (RR: 0.96, 95% CI: 0.93 to 0.99), and oral cancer (OR: 0.51, 95% CI: 0.40 to 0.65). And moderate-quality evidence presented that 200 g increment of fruit intake per day was associated with lower risk of breast cancer (RR: 0.94, 95% CI: 0.89 to 0.99), and the risk of type 2 diabetes mellitus could be reduced by 8%-12% when the fruit intake increasing to 100-500 g/d. For the remaining studies, the quality of evidence was either low or very low. We also found that the study design could influence the significance of the association between fruit intake and health outcomes. Large-sample, multi-center, and multi-country randomized controlled trials or prospective studies are required to verify our results.

Listeriolysin O (LLO) is the main virulence protein of Listeria monocytogenes (LM), that helps LM escape lysosomes. We previously found that the cellular immune response elicited by L.ivanovii (LI) is weaker than that elicited by LM. We speculated that this may be related to the function of ivanolysin O (ILO). Here, we constructed hemolysin gene deletion strain, LIΔilo, and a modified strain, LIΔilo::hly, in which ilo was replaced by hly. Prokaryotic transcriptome sequencing was performed on LI, LIΔilo, and LIΔilo::hly. Transcriptome differences between the three strains were compared, and genes and pathways with significant differences between the three strains were analyzed. Prokaryotic transcriptome sequencing results revealed the relationship of ilo to the ribosome, quorum sensing, and phosphotransferase system (PTS) pathways, etc. LIΔilo exhibited attenuated biofilm formation ability compared to LI. Biofilm formation was significantly recovered or even increased after replenishing hly. After knocking out ilo, the relative expression levels of some virulence genes, including sigB, prfA, actA, smcL, and virR, were up-regulated compared to LI. After replenishing hly, these genes were down-regulated compared to LIΔilo. The trend and degree of such variation were not completely consistent when cultured in media containing only monosaccharides or disaccharides. The results confirmed that hemolysin is related to some important biological properties of Listeria, including biofilm formation and virulence gene expression levels. This is the first comprehensive study on ILO function at the transcriptomic level and the first evidence of a relationship between Listeria hemolysin and biofilm formation.

Hypervirulent and multidrug-resistant Klebsiella pneumoniae poses a significant threat to public health. We aimed to determine the common carbapenemase genotypes and the carriage patterns, main antibiotic resistance mechanisms, and in vitro susceptibility of clinical isolates of carbapenem-resistant K. pneumoniae (CRKP) to ceftazidime/avibactam (CZA) for the reasonable selection of antimicrobial agents and determine whether hypermucoviscous (HMV) phenotype and virulence-associated genes are key factors for CRKP colonization and persistence. Antibiotics susceptibility of clinical CRKP isolates and carbapenemase types were detected. CRKP isolates were identified as hypermucoviscous K. pneumoniae (HMKP) using the string test, and detection of virulence gene was performed using capsular serotyping. The blaKPC-2, blaNDM, blaIMP, and/or blaOXA-48-like were detected in 96.4% (402/417) of the isolates, and the blaKPC-2 (64.7%, 260/402) was significantly higher (PblaNDM (25.1%), blaOXA-48-like (10.4%), and blaIMP (4.2%). Carriage of a single carbapenemase gene was observed in 96.3% of the isolates, making it the dominant antibiotic resistance genotype carriage pattern (P < 0.05). Approximately 3.7% of the isolates carried two or more carbapenemase genotypes, with blaKPC-2 + blaNDM and blaNDM + blaIMP being the dominant multiple antibiotic resistance genotype. In addition, 43 CRKP isolates were identified as HMKP, with a prevalence of 10.3% and 2.7% among CRKP and all K. pneumoniae isolates, respectively. Most clinical CRKP isolates were isolated from elderly patients, and carbapenemase production was the main mechanism of drug resistance. Tigecycline and polymyxin B exhibited exceptional antimicrobial activity against CRKP isolates in vitro. Furthermore, blaKPC-2, blaNDM, and blaOXA-48-like were the main carbapenemase genes carried by the CRKP isolates. CZA demonstrated excellent antimicrobial activity against isolates carrying the single blaKPC-2 or blaOXA-48-like genotype. Capsular serotype K2 was the main capsular serotype of the carbapenem-resistant HMKP isolates. Survival rates of Galleria mellonella injected with K. pneumoniae 1–7 were 20.0, 16.7, 6.7, 23.3, 16.7, 3.3, and 13.3, respectively. Therefore, worldwide surveillance of these novel CRKP isolates and carbapenem-resistant HMKP isolates as well as the implementation of stricter control measures are needed to prevent further dissemination in hospital settings.

Hypervirulent and multidrug-resistant

Expressing heterologous antigens by plasmids may cause antibiotic resistance. Additionally, antigen expression via plasmids is unstable due to the loss of the plasmid. Here, we developed a balanced-lethal system. The Listeria monocytogenes (LM) balanced-lethal system has been previously used as an antigen carrier to induce cellular immune response. However, thus far, there has been no reports on Listeria ivanovii (LI) balanced-lethal systems. The dal and dat genes from the LI-attenuated LIΔatcAplcB (LIΔ) were deleted consecutively, resulting in a nutrient-deficient LIΔdd strain. Subsequently, an antibiotic resistance-free plasmid carrying the LM dal gene was transformed into the nutrient-deficient strain to generate the LI balanced-lethal system LIΔdd:dal. The resultant bacterial strain retains the ability to proliferate in phagocytic cells, as well as the ability to adhere and invade hepatocytes. Its genetic composition was stable, and compared to the parent strain, the balanced-lethal system was substantially attenuated. In addition, LIΔdd:dal induced specific CD4

Maternal betaine supplementation has been proven to alleviate non-alcoholic fatty liver disease (NAFLD) in offspring caused by maternal high-fat diet (MHFD). The gut–liver axis plays an important role in NAFLD pathogenesis. However, whether maternal betaine supplementation can alleviate NAFLD in offspring by the gut–liver axis is unknown. C57BL/6J mice were fed with high-fat diet for 4 weeks before mating, and supplemented with 1% betaine during pregnancy and lactation. After weaning, offspring mice were fed with standard diet to 10 weeks. Maternal betaine supplementation reduced hepatic triglyceride content and alleviated hepatic steatosis in offspring mice exposed to MHFD. Furthermore, the mRNA expression of PPARα, CPT1α and FATP2 was increased and TNFα was reduced by maternal betaine supplementation. Maternal betaine intake decreased the relative abundances of Proteobateria, Desulfovibrio and Ruminococcus, but increased the relative abundances of Bacteroides and Parabacteroides. Moreover, maternal betaine intake increased the concentrations of short-chain fatty acids (SCFAs), including acetic acid, butyric acid and valeric acid, in the feces. Gut microbiota and SCFAs were significantly correlated with hepatic triglyceride content and expression of the above genes. Maternal betaine intake had no effect on other gut microbiota-related metabolites (bile acid and trimethylamine-n-oxide). Altogether, maternal betaine supplementation ameliorated MHFD-induced NAFLD possibly through regulating gut microbiota and SCFAs in offspring mice.

Mangrove sediment microorganisms play a vital role in the energy transformation and element cycling in marine wetland ecosystems. Using metagenomics analysis strategy, we compared the taxonomic structure and gene profile of the mangrove and non-mangrove sediment samples at the subtropical estuary in Beibu Gulf, South China Sea. Proteobacteria, Bacteroidetes, and Firmicutes were the most abundant bacterial phyla. Archaeal family Methanosarcinaceae and bacterial genera Vibrio and Dehalococcoides were significantly higher in the mangrove sediments than in the nonmangrove sediments. Functional analysis showed that "Carbohydrate metabolism" was the most abundant metabolic category. The feature of carbohydrate-active enzymes (CZs) was analyzed using the Carbohydrate-Active EnZymes Database. The significant differences of CZs between mangrove and non-mangrove sediments, were attributed to the amounts of polyphenol oxidase (EC 1.10.3.-), hexosyltransferase (EC 2.4.1.-), and β-N-acetylhexosaminidase (EC 3.2.1.52), which were higher in the mangrove sediment samples. Principal component analysis indicated that the microbial community and gene profile between mangrove and non-mangrove sediments were distinct. Redundancy analysis showed that total organic carbon is a significant factor that affects the microbial community and gene distribution. The results indicated that the mangrove ecosystem with massive amounts of organic carbon may promote the richness of carbohydrate metabolism genes and enhance the degradation and utilization of carbohydrates in the mangrove sediments.

TcpC is a multifunctional virulence factor of Uropathogenic Escherichia coli (UPEC). Macrophages can differentiate into two different subsets M1 and M2 that play distinct roles in anti-infection immunity. Here, we investigate the influence of TcpC on M1/M2 polarization and the potential mechanisms. Our data showed that M1 markers CD86 and iNOS were significantly inhibited, while the M2 markers CD163, CD206 and Arg-1 were enhanced in macrophages in kidneys from the TcpC-secreting wild-type CFT073 (CFT073wt)-infected pyelonephritis mouse model, compared with those in macrophages in kidneys from TcpC knockout CFT073 mutant (CFT073Δtcpc)-infected mice. CFT073wt or recombinant TcpC (rTcpC) treatment inhibits LPS + IFN-γ-induced CD80, CD86, TNF-α and iNOS expression, but promotes IL-4-induced CD163, CD206, Arg-1 and IL-10 expression in both human and mouse macrophage cell lines THP-1 and J774A.1. Moreover, rTcpC significantly attenuated LPS + IFN-γ-induced phosphorylation of p38, ERK, p50 and p65 but enhanced IL-4-induced phosphorylation of Akt and STAT6. These data suggest that TcpC inhibits M1 but promotes M2 macrophage polarization by down-regulation of p38, ERK/NF-κB and up-regulation of the Akt/STAT6 signaling pathway, respectively. Our findings not only illuminate the regulatory effects of TcpC on macrophage M1/M2 polarization and its related signaling pathways, but also provide a novel mechanism underlying TcpC-mediated immune evasion of macrophage-mediated innate immunity.

Background Nerol (C10H18O), an acyclic monoterpene, naturally presents in plant essential oils, and is used widely in food, cosmetics and pharmaceuticals as the valuable fragrance. Meanwhile, chemical synthesis is the only strategy for large-scale production of nerol, and the disadvantages of chemical synthesis greatly limit the production and its application. These defects drive the interests of researchers shift to the production of nerol by eco-friendly methods known as biosynthesis methods. However, the main technical bottleneck restricting the biosynthesis of nerol is the lacking of corresponding natural aroma-producing microorganisms. Results In this study, a novel multi-stress-tolerant probiotics Meyerozymaguilliermondii GXDK6 with aroma-producing properties was identified by whole genome sequencing and metabolomics technology. GXDK6 showed a broad pH tolerance in the range of 2.5–10.0. The species also showed salt tolerance with up to 12% NaCl and up to 18% of KCl or MgCl2. GXDK6 exhibited heavy-metal Mn2+ tolerance of up to 5494 ppm. GXDK6 could also ferment with a total of 21 kinds of single organic matter as the carbon source, and produce abundant aromatic metabolites. Results from the gas chromatography–mass spectrometry indicated the production of 8–14 types of aromatic metabolites (isopentanol, nerol, geraniol, phenylethanol, isobutanol, etc.) when GXDK6 was fermented up to 72 h with glucose, sucrose, fructose, or xylose as the single carbon source. Among them, nerol was found to be a novel aromatic metabolite from GXDK6 fermentation, and its biosynthesis mechanism had also been further revealed. Conclusion A novel aroma-producing M. guilliermondii GXDK6 was identified successfully by whole genome sequencing and metabolomics technology. GXDK6 showed high multi-stress-tolerant properties with acid–base, salty, and heavy-metal environments. The aroma-producing mechanism of nerol in GXDK6 had also been revealed. These findings indicated the aroma-producing M. guilliermondii GXDK6 with multi-stress-tolerant properties has great potential value in the fermentation industry.

The products of bacterial β-glucosidases with favorable cold-adapted properties have industrial applications. A psychrophilic β-glucosidase gene namedbglGfrom subtropical soil microorganismExiguobacteriumsp. GXG2 was isolated and characterized by function-based screening strategy. Results of multiple alignments showed that the derived protein BglG shared 45.7% identities with reviewed β-glucosidases in the UniProtKB/Swiss-Prot database. Functional characterization of the β-glucosidase BglG indicated that BglG was a 468 aa protein with a molecular weight of 53.2 kDa. The BglG showed the highest activity in pH 7.0 at 35 °C and exhibited consistently high levels of activity within low temperatures ranging from 5 to 35 °C. The BglG appeared to be a psychrophilic enzyme. The values ofKm,Vmax,kcat, andkcat/Kmof recombinant BglG towardρNPG were 1.1 mM, 1.4 µg/mL/min, 12.7 s−1, and 11.5 mM/s, respectively. The specific enzyme activity of BglG was 12.14 U/mg. The metal ion of Ca2+and Fe3+could stimulate the activity of BglG, whereas Mn2+inhibited the activity. The cold-adapted β-glucosidase BglG displayed remarkable biochemical properties, making it a potential candidate for future industrial applications.

This paper describes approaches to evaluating the resistance of cement-based composites to sulphate attack. The conventional approach of evaluation by means of measuring expansion is discussed in comparison with the sulphate diffusion, which was quantified as a function of depth. Besides CSA Types GU and HS, a 30:70 blend of fly ash and cement Type GU was also examined. The specimens so produced were immersed in a sulphate solution as per ASTM C1012 and retrieved variously after 7, 14, 28, 56 and 84 days of exposure. As expected, Type HS cement performed best with minimum expansion and sulphate ingress. On the other hand, the Type GU cement showed lower expansion and sulphate ingress in comparison to the fly ash blended binder. Although bearing identical porosity, the blended binder had the smallest median pore size. Therefore, the sulphate ingress and consequent ettringite production likely cracks the blended system more than the other two. Significantly, after longer durations of sulphate exposure, the blended system showed higher tensile strength which implies a healing of cracks through ettringite formation.

3-Deoxy-d-arabino-heptulosonate-7-phosphate synthase (DAHPS) is a key rate-limiting enzyme in aromatic amino acid anabolism. A new Iβ-type DAHPS gene (aro1A) was identified in a metagenomic library from subtropical marine mangrove sediment. The gene encoded a polypeptide composed of 272 amino acids and had a maximum similarity of 52.4% to a known DAHPS at the amino acid level. Multiple sequence alignment, homologous modeling, and molecular docking showed that Aro1A had the typical (β/α)8 barrel-shaped catalytic structural domain of DAHPS. The motifs and amino acid residues involved in the combination of substrates and metal ligand were highly conservative with the known DAHPS. The putative DAHPS gene was subcloned into a pET-30a(+) vector and was overexpressed in Escherichia coli Rosetta (DE3) cells. The recombinant protein was purified to homogeneity. The maximum activity for the recombinant Aro1A protein occurred at pH 8.0 and 40 °C. Ba2+ and Ca2+ stimulated the activity of Aro1A protein. The enzyme showed high affinity and catalytic efficiency (K PEP = 19.58 μM, V PEP = 29.02 μM min−1, and k cat PEP /K PEP = 0.88 s−1 μM−1) under optimal reaction conditions. The enzymatic property of Aro1A indicates its potential in aromatic amino acid industrial production.

L-cistein sulfinat dekarboksilaza (EC 4.1.1.29) je enzim koji određuje brzinu biosinteze taurina, te katalizira dekarboksilaciju L-cistein sulfinskekiseline u hipotaurin. Identifikacija nove L-cistein sulfinat dekarboksilaze koja bi mogla poboljšati biosintetičku učinkovitost taurina vrlo je bitna. Još neistraženi gen za dekarboksilazu, undec1A, identificiran je u prethodnom radu probirom sekvencija DNA iz neuzgojenih mikroorganizama iz tla. Uproteinu Undec1A primjenjena je nasumična mutageneza pomoću sekvencijalne lančane reakcije polimeraze s pogreškama. Mutirani protein Undec1A-1180, izdvojen iz zbirke tako dobivenih različitih mutiranih proteina, imao je 5,62 puta veću specifičnu aktivnost od ishodnogproteina Undec1A pri temperaturi od 35 °C i pH=7,0. Rezultati molekulskog uklapanja potvrđuju da aminokiselinski ostaci Ala235, Val237, Asp239, Ile267, Ala268 i Lys298 u proteinu Undec1A-1180 pomažu pri prepoznavanju i katalizi molekula L-cistein sulfinske kiseline. Ovi bi rezultati mogli poslužiti kao osnova za definiranje svojstava proteina Undec1A-1180.Tehnologija usmjerene evolucije prikladna je za unapređenje biotehnološke primjene gena dobivenih iz metagenoma., L-Cysteine sulfinate decarboxylase (CSD, EC 4.1.1.29), the rate-limiting enzyme in taurine synthesis pathway, catalyzes L-cysteine sulfinic acid to form hypotaurine. Identification of the novel CSD that could improve the biosynthetic efficiency of taurine is important. An unexplored decarboxylase gene named undec1A was identified in a previous work through sequence-based screening of uncultured soil microorganisms. Random mutagenesis through sequential error-prone polymerase chain reaction was used in Undec1A. A mutant Undec1A-1180, which was obtained from mutagenesis library, had 5.62-fold higher specific activity than Undec1A at 35 °C and pH=7.0. Molecular docking results indicated that amino acid residues Ala235, Val237, Asp239, Ile267, Ala268, and Lys298 in the Undec1A-1180 protein helped recognize and catalyze the substrate molecules of L-cysteine sulfinic acid. These results could serve as a basis for elucidating the characteristics of the Undec1A-1180. Directed evolution technology is a convenient way to improve the biotechnological applications of metagenome-derived genes.

This paper empirically tests the adjustment effect from the voluntary disclosure level of the company on the relationship between the executive power intensity and the company performance volatility based on the NEEQ from China. The result shows that the higher the executive power intensity is, the higher the company performance and the greater corporate performance volatility will be; the improvement of executive power has "mixed advantages and disadvantages" for the NEEQ Market and the improvement of the level of voluntary information disclosure can weaken the impact of executive power intensity on the company performance volatility. This research enriches the cognition of the NEEQ, and tries to provide theoretical support for relevant regulatory authorities to standardize the voluntary disclosure of NEEQ.

A novel d-amino acid oxidase (DAAO) gene designated as daoE was cloned by the sequence-based screening of a plasmid metagenomic library of uncultured microorganisms from contaminated agricultural soil. The deduced amino acid sequence comparison and phylogenetic analysis indicated that daoE and other putative DAAOs are closely related. The putative DAAO gene was subcloned into a pETBlue-2 vector and overexpressed in Escherichia coli Tunner(DE3)pLacI. The recombinant protein was purified to homogeneity. The maximum activity of DaoE protein occurred at pH 8.0 and 37 °C. DaoE recombinant protein had an apparent K m of 2.96 mM, V max of 0.018 mM/min, k cat of 10.9/min, and k cat/K m of 1.16 × 104/mol/min. The identification of this novel DAAO gene demonstrated the importance of metagenomic libraries in exploring new d-amino acid oxidases from environmental microorganisms to optimize their applications.

Proteases are typical key enzymes that hydrolyze proteins into amino acids and peptides. Numerous proteases have been studied, but the discovery of metagenome-derived proteases is still significant for both commercial applications and basic research. An unexplored protease gene sep1A was identified by function-based screening from a plasmid metagenomic library derived from uncultured contaminated agricultural soil microorganisms. The putative protease gene was subcloned into pET-32a (+) vector and overexpressed in E. coli BL21(DE3) pLysS, then the recombinant protein was purified to homogeneity. The detailed biochemical characterization of the Sep1A protein was performed, including its molecular characterization, specific activity, pH-activity profile, metal ion-activity profile, and enzyme kinetic assays. Furthermore, the protein engineering approach of random mutagenesis via error-prone PCR was applied on the original Sep1A protein. Biochemical characterization demonstrated that the purified recombinant Ep48 protein could hydrolyze casein. Compared with the original Sep1A protein, the best variant of Ep48 in the random mutagenesis library, with the Gln307Leu and Asp391Gly changes, exhibited 2.62-fold activity at the optimal reaction conditions of 50 °C and pH 9.0. These results are the first step toward a better understanding of the properties of Sep1A protein. Protein engineering with error-prone PCR paves the way toward the metagenome-derived genes for biotechnological applications.

A simple, rapid and ultrasensitive colorimetric method for the determination of propafenone, based on the specific recognition property of propafenone with the unique optical properties of AgNPs, has been developed. The addition of propafenone induced the citrate to be desorbed from the surface of the AgNPs, leading to the aggregation of the AgNPs, accompanied by a dramatic surface plasmon absorption band shift and thereby results in their yellow-to-red even purple color change. The concentration of propafenone can be determined by monitoring with the naked eyes or a UV–Vis spectrophotometer. The detection limit of the present method for propafenone was 2.4 μM. The proposed method is a promising mean for on-site detection of propafenone in actual samples without costly instruments.

A simplified method for synthesis of polyacrylic acid-bound iron oxide magnetic nanoparticles (Fe3O4@PAA NPs) was reported. The as-prepared nanoparticles were characterized by TEM, FT-IR, VSM and XRD. Characterization results indicated that PAA was successfully introduced onto the surface of Fe3O4 and did not cause any changes in magnetic property. The Fe3O4@PAA NPs were used to adsorb rhodamine 6G (R6G) as a model basic dye pollutant from aqueous solution. Kinetics data and adsorption isotherms were better fitted by pseudo-second-order kinetic model and Langmuir isotherm, respectively. The adsorption equilibrium could be reached at about 20 min, showing that the as-prepared adsorbent exhibited extremely rapid adsorption rate. The aqueous solution of the Yellow River was chosen as the test sample, and the results showed that the magnetic adsorbent was efficient for the removal of the basic dye in the real sample.

Bifunctional Fe3O4@MgSiO3 sub-microspheres with superparamagnetic property and high affinity toward metal ions were successfully synthesized via a solvothermal method using Fe3O4@SiO2 as a self-template, and well characterized by means of TEM, XRD, FT-IR, VSM and N2 adsorption isotherms. The as-prepared Fe3O4@MgSiO3 sub-microspheres were then assessed as the adsorbent for Pb2+ removal in water, and various factors influencing the adsorption of Pb2+ were investigated including pH, equilibrium time and initial metal ion concentration. The results indicated that Fe3O4@MgSiO3 sub-microspheres had a mean diameter of 220 nm and high superparamagnetic cores, which endowed them with useful magnetic responsivity. Moreover, the large specific surface was beneficial for their strong affinity toward toxic metal ions. The pseudo-second-order equation could describe well the adsorption kinetics with correlation coefficients greater than 0.999. The maximum adsorption capacity for Pb2+ was calculated to be 242.1 mg/g based on Langmuir model. Furthermore, the as-prepared Fe3O4@MgSiO3 showed an acceptable reusability using NaOH or Mg2+ solution as the desorbing agent. All information gives an indication that the as-prepared sub-microspheres show their potential as the adsorbent for highly efficient removal of heavy metal ions in wastewater.

To understand factors as social support, situation of depression and related risk factors among migrant women of reproductive age in some areas of Wuhan.Cluster sampling method and face-to-face interview with structured questionnaire were used to investigate 316 migrant women in Wuhan.The overall prevalence rate of depression was 32.3%.from binary logistic regression analysis showed that factors as: under pressure (OR = 4.010, 95%CI: 1.672 - 9.617), having had negative life events (OR = 2.050, 95%CI: 1.170 - 3.591) or tight relations with neighbors (OR = 2.537, 95%CI: 1.053 - 6.113), not quite satisfied (OR = 4.247, 95%CI: 1.521 - 11.855) or satisfied (OR = 2.411, 95%CI: 1.111 - 5.233), on his/her own health status etc., might serve as the possible risk factors for depression. In scores related to social support, and the utilization of such support, there were statistically significant differences seen between the groups with depression and the one without.The prevalence of depression among migrant women of reproductive age appeared to be high in some areas on Wuhan. Factors as: under pressure, having had negative life events, tight relations with neighbors, status on satisfaction of one's own health situation as well as related social support, seemed to be the main risk factors for depression in this population.

To detect the possible presence of AI-2 quorum-sensing pathway and construct group B Streptococcus (GBS) mutants with deletion of LuxS gene related to quorum-sensing pathway.V. harveyi BB170 was employed as the reporter strain to detect AI-2 pathway in GBS, and identification of LuxS homologous gene in GBS type V strain 2603 was performed by software-based analysis. LuxS gene deletion mutant Delta LusX was then constructed in GBS by means of allelic exchange and verified by Southern hybridization analysis.A component in the secretions of GBS could induce bioluminescence activity in the reporter strain, suggesting the presence of AI-2 quorum-sensing pathway in GBS. luxS homologous gene was detected in GBS and LuxS gene deletion mutants was successfully constructed in GBS Ia 515 and V 2603 strains.This study establishes a bacterial model for studying the role of LuxS molecule in AI-2 quorum-sensing pathway in GBS and provides new insights into virulence regulation mechanism of GBS.