No abstract available.
Bacteriolysis* ; Galactose* ; Lipopolysaccharides* ; Salmonella typhi* ; Salmonella*

Staphylococcal nuclease A (SNA) may be used to produce bacterial ghosts for further inactivation of host bacteria and elimination of residual genetic materials. It is still controversial if SNA without signal peptide can be secreted to extracellular matrix and if fusion with other peptide is required for its function in the cytoplasm of host bacteria. To clarify this dispute, a series of temperature-inducible plasmids carrying SNA alone or SNA fused with partial sequences of λ phage cro gene (cSNA) or Mycobacterium tuberculosis urease gene (uSNA) were constructed and evaluated in Escherichia coli. Results show that the percentages of inactivated E. coli by SNA, cSNA and uSNA after 4 h of induction were 99.9%, 99.8% and 74.2%, respectively. Moreover, SNA and cSNA in the cytoplasm of host bacteria were initially detectable after 30 min of induction, whereas uSNA was after 1 h. In comparison, SNA and cSNA in culture supernatant were initially detectable 1 h later, whereas uSNA was 2 h later. The nuclease activity in the cytoplasm or supernatant was ranked as follows: SNA > cSNA > uSNA, and the activity in the supernatant was significantly lower than that in the cytoplasm. Furthermore, host genomic DNA was degraded by SNA or cSNA after 2 h of induction but not by uSNA even throughout the whole experiment. In conclusion, this study indicates that SNA, cSNA and uSNA expressed in host bacteria all have nuclease activity, the enzymes can be released to culture media, and fusion with exogenous peptide negatively reduces the nuclease activity of SNA.
Bacteriolysis ; Bacteriophage lambda ; DNA ; chemistry ; Escherichia coli ; Genetic Vectors ; Micrococcal Nuclease ; chemistry ; Plasmids ; Protein Sorting Signals

This study was performed to observe the antibacterial effect of polyphosphate (polyP) with various chain lengths (P3~P75) on virulent, invasive strains of P. gingivalis A7A1-28 and W50, and multidrug resistant E. faecalis ATCC29212. P. gingivalis strains were grown in brain-heart infusion broth (BHI) containing hemin and vitamin K with or without polyP. PolyP was added at the very beginning of the culture or during the exponential growth phase of the culture. Inhibition of the growth of P. gingivalis was determined by measuring the absorbancy at 540nm of the grown cells. Viable cell counts of the culture and release of intracellular nucleotide from P. gingivalis were measured. E. faecalis was grown in plain BHI with antibiotics alone or in combination with polyP(calgon; 0.1~1.0%) and the bacterial absorbancy was measured. The overall results suggest that polyP has a strong antibacterial effect on the growth of the virulent strains of P. gingivalis and the antibacterial activity of polyP seems largely bactericidal, accompanying bacteriolysis in which chelation phenomenon is not involved. Although polyP does not exert antibacterial activity against E. faecalis, it appears to increase antibacterial effect of erythromycin and tetracycline on the bacterium. Therefore, polyP alone or in combination with antibiotics may be developed as a candidate for the agent controlling oral infections including endodontic infection.
Anti-Bacterial Agents ; Bacteria* ; Bacteriolysis ; Cell Count ; Erythromycin ; Hemin ; Polyps ; Tetracycline ; Vitamin K

Bacteriolysis ; physiology ; Bacteriophages ; genetics ; isolation & purification ; physiology ; England ; Gram-Negative Bacteria ; virology ; Humans ; International Cooperation

Lysins are murein hydrolases produced by bacteriophage that act on the cell wall of host bacteria to release progeny phages. Research indicated that lysins could kill bacteria effectively and specifically in vitro. To prepare recombinant bacteriophage lysin of Streptococcus (PlyC) and analyze its biological activity, we obtained two genes of PlyC named PlyCA and PlyCB by PCR amplification and inserted them into pET-32a(+), then transformed the recombinant expression vectors pET-32a(+)-PlyCA and pET-32a(+)-PlyCB into E. coli BL21(DE3) respectively. After induction with 0.7 mmol/L IPTG at 30 degrees C for 7 h, PlyCA and PlyCB were successfully expressed, SDS-PAGE analysis determined that they all constituted above 30% of the total cell proteins. After Ni(2+)-NTA affinity chromatography, the purity was more than 95%. With the denaturation and protein refolding, we gained the recombinant PlyC. To determine its biological activity, we adopted turbidimetry and plate count method. Before and after lysin treatment, the cell morphology was studied by scanning electron microscopy (SEM). The results showed that the recombinant PlyC could specifically cleavage Streptococcus pyogenes (group A beta-hemolytic streptococci). Under the incubation time of 60 min with 4 microg/mL PlyC in Streptococcus pyogenes dilution which OD600 was 0.56, the germicidal effect was up to 99.6%, while SEM observations showed that cell wall cracked and presented cell debris. This finding laid the foundation for the further study and achieving an effective treatment for streptococcal infection.
Bacteriolysis ; Enzymes ; biosynthesis ; genetics ; isolation & purification ; Escherichia coli ; genetics ; metabolism ; Recombinant Proteins ; biosynthesis ; genetics ; isolation & purification ; Streptococcus pyogenes ; drug effects

It is generally believed that tumor necrosis factor alpha (TNF a) plays an crucial role in the pathogenesis of bacterial meningitis through various mechanisms such as endothelial damage, induction of adhesion molecule on the endothelial cell, recruitment of leukocytes in the cerebrospinal fluid(CSF). We performed this study to analyze the relationship of TNF alpha level with the severity of inflammation in the CSF. In a rabbit meningitis model, we attempted to evaluate whether antibiotics induced bacteriolysis can induce the elevation of the TNF alpha level and pleocytosis in CSF, and whether dexamethasone can suppress this elevation of TNF alpha. We also tried to assess the effective administation timing of dexamethasone. Meningitis was induced by intracistemal inoculation of Streptococcus pneumoniae. We designed four groups : Group 1. Untreated conrol (N=5); Group 2. Lone ceftriaxone at 6 hours after inoculation (N=5) ; Group 3. Dexamethasone at 30 minutes before ceftriaxone treatment (N=5); Group 4. Dexamethasone at 30 min. after ceftriaxone treatment (N=5). CSF TNF alpha level and cell count was assessed with regular time interval. The results were as follows: First, the CSF bacterial counts (measured by colony forming units) of group 1 was significantly higher than the other groups after ceftriaxone treatment (P<0. 05). Second, the CSF WBC counts of group 3 and 4 were significantly lower than those of group 1 and 2 at 6 and 14 hours after ceftriaxone treatment (P<0.05). Third, the CSF TNF alpha titers of group 1 and 3 were significantly lower than those of group 2 and 4 at 2 hours after ceftriaxone treatment (P<0.05). Fourth, after 14 hours, the CSF TNF alpha titers of group 1 kept on rising and became significantly higher than those of other groups (P Anti-Bacterial Agents ; Bacterial Load ; Bacteriolysis ; Ceftriaxone ; Cell Count ; Dexamethasone* ; Endothelial Cells ; Inflammation* ; Leukocytes ; Leukocytosis ; Meningitis ; Meningitis, Bacterial ; Meningitis, Pneumococcal* ; Streptococcus pneumoniae ; Tumor Necrosis Factor-alpha

AIMTo investigate the inhibitory effect of egg white lysozyme (LZM) on ceftazidime (CFT)-induced release of endotoxin from Pseudomonas aeruginosa.

METHODSP. aeruginosa PAO1 was inoculated in nutrition broth or diluted rabbit blood free of antibiotics in the presence or absence of LZM and incubated at 37 degrees C on a water bath shaker. beta-Lactam antibiotic, CFT, was added to cultures at 3.5 h (nutrition broth culture) or 5 h (diluted rabbit blood culture) after inoculation. After 3 h of CFT treatment, the supernatants from different bacterial cultures were prepared by centrifuge and the concentrations of endotoxin in the supernatants were measured. The bacterial supernatants were also added to a murine macrophage cell line RAW 264.7 or intravenously injected into carrageenin-sensitized mice. Tumor necrosis factor-alpha (TNF alpha) and nitric oxide (NO) concentrations in RAW 264.7 supernatants or in mouse sera were tested.

RESULTSCFT treatment alone obviously inhibited the growth of P. aeruginosa PAO1 accompanied by strong and rapid bacteriolysis and released relatively high concentration of endotoxin from bacteria both in nutrition broth and in diluted rabbit blood cultures. The bacterial supernatant from CFT treatment alone yielded high concentrations of TNF alpha both in RAW 264.7 cells and in mice and high level of NO in RAW 264.7 cells. Treatment with the combination of LZM and CFT evidently blocked the lysis of bacteria and reduced the release of endotoxin without decreasing bactericidal activity of CFT. TNF alpha and NO productivity of the supernatants prepared from the LZM/CFT combinative treated bacterial cultures were significantly decreased both in RAW 264.7 cells and in mice indicating that the inflammatory activity was reduced.

CONCLUSIONLZM can effectively prevent CFT-induced bacteriolysis, endotoxin release and subsequent proinflammatory factor production but without decreasing bactericidal activity of CFT, resulting in the disassociation of bactericidal activity and bacteriolysis. Thus, LZM might be important for preventing endotoxemia in Gram-negative sepsis with the treatment of antibiotics.

Animals ; Bacteriolysis ; drug effects ; Ceftazidime ; pharmacology ; Egg White ; analysis ; Endotoxins ; metabolism ; Mice ; Muramidase ; isolation & purification ; pharmacology ; Nitric Oxide ; metabolism ; Pseudomonas aeruginosa ; metabolism ; physiology ; Rabbits ; Tumor Necrosis Factor-alpha ; metabolism

Bacterial ghost is intact envelope of Gram-negative bacteria, which is produced by the function of the lysis gene E from bacteriophage PhiX174. The expression of the lysis gene E is usually controlled by the thermosensitive lambdapL/pR-cI857 promoter. In this study, we described a mutation (T --> C) at the ninth nucleotide of the OR2 in the lambdapR promoter of the lambdapL/pR-cI857 system by overlap PCR. The bacteriolytic assay showed that the mutation in the lambdapL/pR-cI857 system enhanced the temperature of repressing the expression of gene E up to 37 degrees C. The lysis efficiency of altered lambdapR promoter in Escherichia coli DH5a and avian pathogenic E. coli DE17 was up to 99.9%. The expanded range of temperature will benefit for the production of bacterial ghost.
Bacteriolysis ; physiology ; Bacteriophage lambda ; genetics ; Base Sequence ; Cell Membrane ; physiology ; DNA, Bacterial ; analysis ; Escherichia coli ; genetics ; growth & development ; physiology ; virology ; Gene Expression Regulation ; genetics ; Molecular Sequence Data ; Mutation ; Promoter Regions, Genetic ; genetics ; Viral Proteins ; genetics ; metabolism