变异链球菌和血链球菌全代谢途径比对分析

为了比较变异链球菌和血链球菌全代谢途径,依据KEGG数据库(http://www.genome.ad.jp/kegg)对变异链球菌和血链球菌的全部代谢途径作逐项比对。结果显示,二者参与了85个代谢途径,包括多数以相同的酶参与的中央代谢途径,即糖酵解、三羧酸循环、磷酸戊糖途径等,和多数以不同的酶参与的双组分感应系统等。通过变异链球菌和血链球菌整体代谢网络对比,了解了变异链球菌和血链球菌理论上的全部代谢途径,为全面揭示二者代谢交流研究奠定了基础。     

Phenotypic characteristics of Streptococcus iniae and Streptococcus parauberis isolated from olive flounder (Paralichthys olivaceus)

The etiological agents of streptococcosis were isolated from diseased olive flounder collected on the Jeju island of Korea. A total of 151 bacterial isolates were collected between 2003 and 2006. The isolates were examined using various phenotypic and proteomic analyses, including sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), immunoblotting, and glycoprotein assays. In addition, isolates were grown on blood agar to assess hemolytic activity, and biochemical assays were performed using the API20 Strep kit. Our results revealed that all isolates were nonmotile, Gram-positive cocci that displayed negative catalase and oxidase activities. Multiplex PCR assays revealed that 43% and 57% of the isolates were Streptococcus iniae and Streptococcus parauberis , respectively. These results were consistent with those of the SDS-PAGE and immunoblot analyses using whole-cell lysates of bacterial isolates. Significant differences were observed with respect to the Voges–Proskauer, pyrrodonyl arylamidase, alkaline phosphatase, and hemolytic activities of the S. iniae and S. parauberis isolates. Isolates of S. iniae displayed uniform profiles in the immunoblot and glycoprotein assays; however, immunoblot assays of S. parauberis isolates (using a chicken IgY antibody raised against a homologous isolate) revealed three distinct antigenic profiles. Our findings suggest that S. parauberis and S. iniae are endemic pathogens responsible for the development of streptococcosis in olive flounder.     

Tea extracts differentially inhibit Streptococcus mutans and Streptococcus sobrinus biofilm colonization depending on the steeping temperature

Abstract

This study aimed to evaluate the effects of tea extracts on oral biofilm colonization depending on steeping temperature. S. mutans and S. sobrinus were cultured and treated with green or black tea extracts prepared under different steeping conditions. Biofilm formation, glucosyltransferase (GTF) levels, bacterial growth, and acidogenicity were evaluated. Biofilms were also assessed by gas chromatography-mass spectrometry and confocal laser scanning microscopy. All extracts with hot steeping showed higher inhibitory effects on biofilm formation and cell viability and lower GTF levels compared with those with cold steeping (p?<?0.05). Hot steeping significantly reduced bacterial growth (p?<?0.05) and maintained the pH. Catechins were only identified from hot steeping extracts. Within the limits of this study, extracts with cold steeping showed lower inhibitory effects on oral biofilms. The different effects between steeping extracts may be attributed to the difference in catechins released from tea extracts under the different steep conditions.     

Versatility of choline metabolism and choline-binding proteins in Streptococcus pneumoniae and commensal streptococci

The pneumococcal choline-containing teichoic acids are targeted by choline-binding proteins (CBPs), major surface components implicated in the interaction with host cells and bacterial cell physiology. CBPs also occur in closely related commensal species, Streptococcus oralis and Streptococcus mitis , and many strains of these species contain choline in their cell wall. Physiologically relevant CBPs including cell wall lytic enzymes are highly conserved between Streptococcus pneumoniae and S. mitis . In contrast, the virulence-associated CBPs, CbpA, PspA and PcpA, are S. pneumoniae specific and are thus relevant for the characteristic properties of this species.     

Streptococcus mutans glucan-binding protein-A affects Streptococcus gordonii biofilm architecture

The glucan-binding protein-A (GbpA) of Streptococcus mutans has been shown to contribute to the architecture of glucan-dependent biofilms formed by this species and influence virulence in a rat model. As S. mutans synthesizes multiple glucosyltransferases and nonglucosyltransferase glucan-binding proteins (GBPs), it is possible that there is functional redundancy that overshadows the full extent of GbpA contributions to S. mutans biology. Glucan-associated properties such as adhesion, aggregation, and biofilm formation were examined independently of other S. mutans GBPs by cloning the gbpA gene into a heterologous host, Streptococcus gordonii, and derivatives with altered or diminished glucosyltransferase activity. The presence of GbpA did not alter dextran-dependent aggregation nor the initial sucrose-dependent adhesion of S. gordonii. However, expression of GbpA altered the biofilm formed by wild-type S. gordonii as well as the biofilm formed by strain CH107 that produced primarily alpha-1,6-linked glucan. Expression of gbpA did not alter the biofilm formed by strain DS512, which produced significantly lower quantities of parental glucan. These data are consistent with a role for GbpA in facilitating the development of biofilms that harbor taller microcolonies via binding to alpha-1,6-linkages within glucan. The magnitude of the GbpA effect appears to be dependent on the quantity and linkage of available glucan.     

Influence of fluoride on the bacterial composition of a dual-species biofilm composed of Streptococcus mutans and Streptococcus oralis

Despite the widespread use of fluoride for the prevention of dental caries, few studies have demonstrated the effects of fluoride on the bacterial composition of dental biofilms. This study investigated whether fluoride affects the proportion of Streptococcus mutans and S. oralis in mono- and dual-species biofilm models, via microbiological, biochemical, and confocal fluorescence microscope studies. Fluoride did not affect the bacterial count and bio-volume of S. mutans and S. oralis in mono-species biofilms, except for the 24-h-old S. mutans biofilms. However, fluoride reduced the proportion and bio-volume of S. mutans but did not decrease those of S. oralis during both S. oralis and S. mutans dual-species biofilm formation, which may be related to the decrease in extracellular polysaccharide formation by fluoride. These results suggest that fluoride may prevent the shift in the microbial proportion to cariogenic bacteria in dental biofilms, subsequently inhibiting the cariogenic bacteria dominant biofilm formation.     

Identification of lactoferrin-binding proteins in Streptococcus dysgalactiae subsp. dysgalactiae and Streptococcus agalactiae isolated from cows with mastitis

Three strains of Streptococcus dysgalactiae subsp. dysgalactiae (S. dysgalactiae) and five strains of Streptococcus agalactiae were used to identify lactoferrin-binding proteins (LBPs). LBPs from extracted surface proteins were detected by polyacrylamide gel electrophoresis and Western blotting. All strains of S. dysgalactiae evaluated had 52- and 74-kDa protein bands. All strains of S. agalactiae evaluated had 52-, 70- and 110-kDa protein bands. In addition, a 45-kDa band was detected in two of five S. agalactiae strains evaluated. This study demonstrated that S. dysgalactiae and S. agalactiae of bovine origin contain two and three major LBPs, respectively.     

Heterologous expression of an endoglucanase gene (endA) from the ruminai anaerobe Ruminococcus flavefaciens 17 in Streptococcus bovis and Streptococcus sanguis

Abstract The heterologous expression of a cloned endoglucanase gene ( endA ) from the ruminai bacterium Ruminococcus flavefaciens 17 was demonstrated in the Streptococcus species S. bovis JB1 and S. sanguis DLL The endA gene was introduced into S. bovis and S. sanguis using the Escherichia coli/Streptococcus shuttle vector pVA838. Expression of the gene was detected by clearing zones around the recombinant colonies on agar plates containing carboxymethylcellulose stained with Congo red. S. bovis JB1 containing the endA gene was capable of utilizing cellotetraose at a faster rate than the parent strain. This is the first demonstration that Streptococcus species can express a gene from a Ruminococcus flavefaciens strain.     

In vitro compared activity of telithromycin and azithromycin against northwest Italian isolates of Streptococcus pyogenes and Streptococcus pneumoniae with different erythromycin susceptibility

Aims: This study compared the in vitro activity of telithromycin with that of azithromycin against 438 Streptococcus pyogenes and 198 Streptococcus pneumoniae, isolated over the period 2005–2007 from specimens of different human origin obtained in three Piemonte Region’s hospitals. Methods and Results: The determination of antimicrobial activity was evaluated by the microdilution broth method and the erythromycin‐resistant (Ery‐R) phenotypes by the triple‐disc test. Exactly 78·8% of S. pyogenes and 69·2% of S. pneumoniae were erythromycin‐susceptible (Ery‐S). Concerning S. pyogenes, telithromycin was active against M and inducible MLS_B, subtype‐C, phenotypes but not against constitutive MLS_B strains. Telithromycin acted well against all S. pneumoniae, irrespective of their mechanism of macrolide‐resistance. On the contrary, the Ery‐R isolates, both S. pyogenes and S. pneumoniae, were resistant to azithromycin. Conclusions: Our results indicate that macrolide resistance in streptococci still persist in northwest Italy (21·2% of S. pyogenes and 30·8% of S. pneumoniae) and that telithromycin is confirmed as being extremely active even against recent clinical Ery‐R streptococcal isolates. Significance and Impact of the Study: The present study emphasizes that an active surveillance of the phenotype distribution and antibacterial resistance in streptococci is essential in guiding the effective use of empirical treatment option for streptococcal infections, also at regional level.     

Isolation and characterisation of promoter regions from Streptococcus thermophilus

Abstract Four promoter regions required for the expression of a promoterless antibiotic resistance gene ( cat194 ) in Streptococcus thermophilus were isolated by random chromosomal cloning experiments. These were shown to be functional in vivo, and their sequences were determined. Each region expressed different amounts of Cat protein as determined by enzyme activities. One region, STP10, was found to contain the 5' coding region of the large ribosomal subunit protein L20.     

The effect of oxygen on the growth and acid production of Streptococcus mutans and Streptococcus sanguis

Abstract Pure cultures of Streptococcus mutans NCTC 10499 and Streptococcus sanguis ATCC10556 were grown in a glucose-limited chemostat under varying concentrations of oxygen in the gas phase. Both streptococci consumed large amounts of oxygen by the partial oxidation of sugars, thus maintaining an anaerobic environment. With increasing oxygen concentrations the degradation products from glucose become more oxidized. Ethanol gradually disappeared from the culture fluid while the acetate concentration increased. In the case of S. sanguis , the products became even more oxidized at higher oxygen concentrations, and carbon dioxide was formed instead of formate. Sudden increase in the oxygen concentration in the gas phase caused elevated oxygen tensions in the cultures, which led to a decrease in the growth rate of the streptococci.     

血链球菌与疾病研究进展

血链球菌是早期定植在口腔内的细菌之一,也是口腔内的常驻菌.血链球菌作为牙周有益菌对大多数牙周可疑致病菌具有拮抗作用.其主要机制为产生过氧化氢和血链素.由于各种原因进入血液循环后可引起感染性心内膜炎,主要机制为血链球菌的表面抗原使血小板产生黏附、聚集,其在血小板表面的结合位点在血小板膜糖蛋白Ib附近.单核细胞在血链球菌的刺激下表达大量的组织因子,激活外源性凝血途径形成血栓.     

Chondroitinase C activity of Streptococcus intermedius

Chondroitin 6-sulfate depolymerizing activity was examined in the culture supernatant of Streptococcus intermedius ATCC 27335. 2-Acetamido-2-deoxy-3-O-(beta-D-gluco-4-enepyranosyluronic acid)-6-O-sulfo-D-galactose was split from the substrate. The enzyme(s) was not active upon chondroitin 4-sulfate or dermatan sulfate, which indicated that the enzyme responsible for the depolymerization is chondroitinase C.     

Species-specific PCR method for identification of Streptococcus downei

AIMS: To establish a rapid method to differentiate Streptococcus downei and S. sobrinus by multiplex PCR. METHODS AND RESULTS: A PCR primer pair specific to S. downei was designed on the basis of the nucleotide sequence of the dextranase gene of S. downei NCTC 11391T. The primer pair specifically detected S. downei, but none of the other mutans streptococci (16 strains of six species). The PCR procedure was capable of detecting 1 pg of genomic DNA purified from S. downei NCTC 11391 and as few as 14 CFU of S. downei cells. The mixture of primer pairs specific to each S. downei (this study) and S. sobrinus (Igarashi et al. 2000) detected only the strains of these two species among all the mutans streptococcal strains, and concomitantly differentiated the two species by species-specific amplicons of different lengths. CONCLUSIONS: The present PCR method is highly specific to S. downei and is useful for detection and identification of S. downei. SIGNIFICANCE AND IMPACT OF THE STUDY: Multiplex PCR using dextranase gene primers is a useful method for simultaneous detection and differentiation of S. downei and S. sobrinus.     

Infection of Streptococcus oralis NCTC 11427 by pneumococcal phages

We have found a group of pneumococcal bacteriophages (Cp-1, Cp-7) that can successfully infect and replicate in Streptococcus oralis, whereas Dp-1 was unable to infect this species. We have also developed conditions that allowed transfection of S. oralis using Dp-1 DNA. Our results support the direct involvement of the phage-coded lysins in the liberation of the phage progeny from infected S. oralis cells. Since S. oralis and S. pneumoniae are bacteria that share the same ecological niche in humans, the availability of the system described here should allow to extend our current studies on the modular organization of the lytic enzymes and might serve as a tool to study the evolutionary relationships between host and parasite.     

Involvement of human mucous saliva and salivary mucins in the aggregation of the oral bacteria Streptococcus sanguis,Streptococcus oralis,and Streptococcus rattus

The contribution of human parotid (Par) and submandibular/sublingual (SM/SL) saliva and of the human whole salivary mucin fraction (HWSM) to saliva-induced bacterial aggregation was studied for S. sanguis C476, S. oralis I581, and S. rattus HG 59. The mucous SM/SL saliva showed a much higher aggregation potency towards the S. sanguis and S. oralis strain than did the serous Par saliva. The SM/SL saliva-induced aggregation was observed after 30 min, at 60 min followed by the Par saliva-induced aggregation, and showed a 4-fold higher aggregation titer of 128 for S. sanguis, and an 8-fold higher titer of 516 for S. oralis. In contrast, the Par saliva showed a slightly higher aggregation activity than the SM/SL saliva towards S. rattus as judged by a twofold higher titer of 64. Morphologically, however, the SM/SL saliva-induced aggregation of S. rattus was far more pronounced as was also found for S. sanguis. Finally, the HWSM-induced aggregation showed a 4 to 8-fold higher titer than the originating salivary source, measuring 2048 for S. oralis and 128 for S. rattus. Moreover, no difference was observed in aggregation activity between the HWSM from whole saliva of a blood group O donor and the HWSM from SM/SL saliva of a blood group A donor. All the data point to an important, though not exclusive role of the human salivary mucin fraction in the saliva-induced aggregation of these strains.     

Improved electroporation protocol and vectors for Streptococcus bovis

An improved method for electroporation of the ruminal bacterium Streptococcus bovis was developed. The organism was grown aerobically in hyperosmotic medium in the presence of 0.5% (w/v) glycine, and electroporation was carried out in a sucrose-glycerol solution with a field strength of 12.5kV/cm, 200 resistance and 25F capacitance. Electroporation efficiencies of 0.5 to 2.0 × 105 transformants/g DNA were achieved. Improved vectors for S. bovis were developed that include a multiple cloning site, and also a promoter region from the S. bovis intracellular amylase gene that may serve as an expression system for foreign genes.