Degradation of chlorobenzenes at nanomolar concentrations by Burkholderia sp. strain PS14 in liquid cultures and in soil.

The utilization of 1,2,4,5-tetrachloro-, 1,2,4-trichloro-, the three isomeric dichlorobenzenes and fructose as the sole carbon and energy sources at nanomolar concentrations was studied in batch experiments with Burkholderia sp. strain PS14. In liquid culture, all chlorobenzenes were metabolized within 1 h from their initial concentration of 500 nM to below their detection limits of 0.

Bacteria designed for bioremediation.

Although many environmental pollutants are efficiently degraded by microorganisms, others persist and constitute a severe health hazard. In some instances, persistence is a consequence of the inadequate catabolic potential of the available microorganisms. Gene technology, combined with a solid knowledge of catabolic pathways and microbial physiology, enables the experimental evolution of new or improved catabolic activities for such pollutants.

Initial reactions in the biodegradation of 1-chloro-4-nitrobenzene by a newly isolated bacterium, strain LW1.

Bacterial strain LW1, which belongs to the family Comamonadaceae, utilizes 1-chloro-4-nitrobenzene (1C4NB) as a sole source of carbon, nitrogen, and energy. Suspensions of 1C4NB-grown cells removed 1C4NB from culture fluids, and there was a concomitant release of ammonia and chloride. Under anaerobic conditions LW1 transformed 1C4NB into a product which was identified as 2-amino-5-chlorophenol by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry.

Identification of pneumococcal surface protein A as a lactoferrin-binding protein of Streptococcus pneumoniae.

Lactoferrin (Lf), an iron-sequestering glycoprotein, predominates in mucosal secretions, where the level of free extracellular iron (10(-18) M) is not sufficient for bacterial growth. This represents a mechanism of resistance to bacterial infections by prevention of colonization of the host by pathogens. In this study we were able to show that Streptococcus pneumoniae specifically recognizes and binds the iron carrier protein human Lf (hLf).

Protective immune response against Streptococcus pyogenes in mice after intranasal vaccination with the fibronectin-binding protein SfbI.

Despite the significant impact on human health of Streptococcus pyogenes, an efficacious vaccine has not yet been developed. Here, the potential as a vaccine candidate of a major streptococcal adhesin, the fibronectin-binding protein SfbI, was evaluated. Intranasal immunization of mice with either SfbI alone or coupled to cholera toxin B subunit (CTB) triggered efficient SfbI-specific humoral (mainly IgG) and lung mucosal (14% of total IgA) responses.

Salmonella vaccine carrier strains: effective delivery system to trigger anti-tumor immunity by oral route.

Recombinant Salmonella strains expressing heterologous antigens can be delivered by oral route triggering the elicitation of efficient antigen-specific humoral, T helper and cytotoxic responses. The potential of attenuated Salmonella spp. to trigger anti-tumor immunity was evaluated for the first time by using beta-galactosidase (beta-gal) as a model tumor-associated antigen (TAA).

Streptococcal invasion.

The genus Streptococcus consists of large number of species many of which are pathogenic to humans and animals. Although streptococci have long been considered as extracellular pathogens, they are capable of causing serious invasive infections such as necrotizing fasciitis and meningitis. Streptococcal invasion, therefore, has been a focus of many studies in recent years.

Pathogenicity island 2 mutants of Salmonella typhimurium are efficient carriers for heterologous antigens and enable modulation of immune responses.

The potential use as vaccine delivery system of Salmonella typhimurium strains harboring defined mutations in the sseC (HH104) and sseD (MvP101) genes, which encode putative effector proteins of the type III secretion system of Salmonella pathogenicity island 2, was evaluated and compared with that of the well-characterized aroA mutant strain SL7207 by using beta-galactosidase (beta-Gal) as a model antigen. When orally administered to immune-competent or gamma interferon-deficient (IFN-gamma-/-) BALB/c mice, both mutants were found to be highly attenuated (50% lethal dose, >10(9) bacteria). Both strains were also able to efficiently colonize and persist in Peyer's patches.

Thermal gradient gel electrophoresis analysis of bioprotection from pollutant shocks in the activated sludge microbial community.

We used a culture-independent approach, namely, thermal gradient gel electrophoresis (TGGE) analysis of ribosomal sequences amplified directly from community DNA, to determine changes in the structure of the microbial community following phenol shocks in the highly complex activated sludge ecosystem. Parallel experimental model sewage plants were given shock loads of chlorinated and methylated phenols and simultaneously were inoculated (i) with a genetically engineered microorganism (GEM) able to degrade the added substituted phenols or (ii) with the nonengineered parental strain. The sludge community DNA was extracted, and 16S rDNA was amplified and analyzed by TGGE.

Genetic and biochemical analyses of the tec operon suggest a route for evolution of chlorobenzene degradation genes.

The TecA broad-spectrum chlorobenzene dioxygenase of Burkholderia sp. strain PS12 catalyzes the first step in the mineralization of 1,2,4, 5-tetrachlorobenzene. The catabolic genes were localized on a small plasmid that belongs to the IncPbeta incompatibility group.

Fibronectin-binding protein I of Streptococcus pyogenes promotes T cell-independent proliferation of murine B lymphocytes and enhances the expression of MHC class II molecules on antigen-presenting cells.

We have previously shown that fibronectin-binding protein I (SfbI) of Streptococcus pyogenes can act as an adjuvant for mucosal-delivered antigens (Medina, E., Talay, S. R.

Identification of chlorobenzene dioxygenase sequence elements involved in dechlorination of 1,2,4,5-tetrachlorobenzene.

The TecA chlorobenzene dioxygenase and the TodCBA toluene dioxygenase exhibit substantial sequence similarity yet have different substrate specificities. Escherichia coli cells producing recombinant TecA enzyme dioxygenate and simultaneously eliminate a halogen substituent from 1,2,4,5-tetrachlorobenzene but show no activity toward benzene, whereas those producing TodCBA dioxygenate benzene but not tetrachlorobenzene. A hybrid TecA dioxygenase variant containing the large alpha-subunit of the TodCBA dioxygenase exhibited a TodCBA dioxygenase specificity.

A putative lichenysin A synthetase operon in Bacillus licheniformis: initial characterization.

Certain Bacillus licheniformis strains isolated from oil wells have been shown to produce a very effective biosurfactant, lichenysin A, which is structurally similar to another less active lipopeptide, surfactin. Surfactin, like many small peptides in prokaryotes and lower eukaryotes, is synthesized non-ribosomally by multi-enzyme peptide synthetase complex. Analysis of several peptide synthetases of bacterial and fungal origin has revealed a high degree of sequence conservation.

Degradation of 1,2,3,4-tetrachlorobenzene by pseudomonas chlororaphis RW71.

Pseudomonas chlororaphis RW71 mineralized 1,2,3,4-tetrachlorobenzene, a highly recalcitrant pollutant hitherto not known to be degraded by pure cultures, as a sole source of carbon and energy, thereby releasing stoichiometric amounts of chloride. The transient excretion of tetrachlorocatechol in the early growth phase suggests an initial attack by a dioxygenase to form the corresponding dihydrodiol which rearomatizes to the catechol. The activity of chlorocatechol 1,2-dioxygenase in crude cell extracts was found to be extraordinarily high towards 3-chlorocatechol (ratio of 2.

A second two-component regulatory system of Bordetella bronchiseptica required for bacterial resistance to oxidative stress, production of acid phosphatase, and in vivo persistence.

Random minitransposon mutagenesis was used to identify genes involved in the survival of Bordetella bronchiseptica within eukaryotic cells. One of the mutants which exhibited a reduced ability to survive intracellularly harbored a minitransposon insertion in a locus (ris) which displays a high degree of homology to two-component regulatory systems. This system exhibited less than 25% amino acid sequence homology to the only other two-component regulatory system described in Bordetella spp.

Alcanivorax borkumensis gen. nov., sp. nov., a new, hydrocarbon-degrading and surfactant-producing marine bacterium.

During screening for biosurfactant-producing, n-alkane-degrading marine bacteria, six heterotrophic bacterial strains were isolated from enriched mixed cultures, obtained from sea water/sediment samples collected near the isle of Borkum (North Sea), using Mihagol-S (C14,15-n-alkanes) as principal carbon source. These Gram-negative, aerobic, rod-shaped bacteria use a limited number of organic compounds, including aliphatic hydrocarbons, volatile fatty acids, and pyruvate and its methyl ether. During cultivation on n-alkanes as sole source of carbon and energy, all strains produced both extracellular and cell-bound surface-active glucose lipids which reduced the surface tension of water from 72 to 29 mN m-1 (16).

Pas, a novel protein required for protein secretion and attaching and effacing activities of enterohemorrhagic Escherichia coli.

Enterohemorrhagic Escherichia coli (EHEC) exhibits a pattern of localized adherence to host cells, with the formation of microcolonies, and induces a specific histopathological phenotype collectively known as the attaching and effacing lesion. The genes encoding the products responsible for this phenotype are located on a 35-kb pathogenicity island designated the locus of enterocyte effacement, which is also shared by enteropathogenic E. coli.

Biochemical and genetic characterization of a gentisate 1, 2-dioxygenase from Sphingomonas sp. strain RW5.

A 4,103-bp long DNA fragment containing the structural gene of a gentisate 1,2-dioxygenase (EC 1.13.11.

Genetic analysis of dioxin dioxygenase of Sphingomonas sp. Strain RW1: catabolic genes dispersed on the genome.

The dioxin dioxygenase of Sphingomonas sp. strain RW1 activates dibenzo-p-dioxin and dibenzofuran for further metabolism by introducing two atoms of oxygen at a pair of vicinal carbon atoms, one of which is involved in one of the bridges between the two aromatic rings, i.e.

Multifunctional g3p-peptide tag for current phage display systems.

We have previously described a monoclonal antibody (mAb), 10C3, directed against the gene-3 protein (g3p) of filamentous phage M13, which was produced to study g3p fusion protein expression in Escherichia coli and its incorporation in the phage capsid [Tesar, M., Beckmann, C., Röttgen, P.

The reductase RedA2 of the multi-component dioxin dioxygenase system of Sphingomonas sp. RW1 is related to class-I cytochrome P450-type reductases.

The first step in the oxidation of the diaryl ethers dibenzo-p-dioxin and dibenzofuran by the bacterium Sphingomonas sp. RW1 is carried out by an atypical multi-component ring hydroxylating dioxygenase. This heteromeric enzyme requires the participation of a flavoprotein, reductase A2, and an iron-sulfur protein, Fdx1, to mediate the transfer of electrons from NADH to the dioxygenase for oxygen activation [Bünz, P.

Attenuated Listeria monocytogenes carrier strains can deliver an HIV-1 gp120 T helper epitope to MHC class II-restricted human CD4+ T cells.

Listeria monocytogenes is a facultative intracellular pathogen which, following uptake by macrophages, escapes from the phagosome and replicates in the cytoplasm. This property has been exploited using recombinant L. monocytogenes as a carrier for the intracytoplasmic expression of antigens when MHC class I-restricted cytotoxic T lymphocyte responses are required.

Invasion and survival of Streptococcus pyogenes in eukaryotic cells correlates with the source of the clinical isolates.

The invasiveness of 96 group A streptococci (GAS) isolates (56 from throat or skin and 40 from blood) were analyzed. GAS invasion strongly correlated with the source of the isolates, whereas no correlation was observed with the Vir type. Isolates from throat or skin exhibited the highest invasion efficiency (57% were between 0.

Fibronectin-binding protein I of Streptococcus pyogenes is a promising adjuvant for antigens delivered by mucosal route.

A common problem in human vaccinology is the limited availability of efficient and non-toxic adjuvants capable of promoting mucosal responses. The potential usefulness of fibronectin-binding protein I (Sfbl) of Streptococcus pyogenes as immunological adjuvant was assessed using ovalbumin (OVA) as a model antigen. Mice were immunized by intranasal route, either with soluble OVA or OVA covalently coupled to Sfbl.