An improved Tn7-lux reporter for broad host range, chromosomally-integrated promoter fusions in Gram-negative bacteria.

An improved vector for chromosomally-integrated promoter-lux fusions is described. The modified vector was tested in parallel with the unmodified vector using the well-characterized Escherichia coli araBAD promoter in the Pseudomonas aeruginosa attTn7 site. The modified mini-Tn7 showed reduced background luminescence, and increased luminescence upon induction, giving >16-fold higher induction ratio.

Role for ferredoxin:NAD(P)H oxidoreductase (FprA) in sulfate assimilation and siderophore biosynthesis in Pseudomonads.

Pyridine-2,6-bis(thiocarboxylate) (PDTC), produced by certain pseudomonads, is a sulfur-containing siderophore that binds iron, as well as a wide range of transition metals, and it affects the net hydrolysis of the environmental contaminant carbon tetrachloride. The pathway of PDTC biosynthesis has not been defined. Here, we performed a transposon screen of Pseudomonas putida DSM 3601 to identify genes necessary for PDTC production (Pdt phenotype).

The role of the siderophore pyridine-2,6-bis (thiocarboxylic acid) (PDTC) in zinc utilization by Pseudomonas putida DSM 3601.

Previous work had suggested that in addition to serving the function of a siderophore, pyridine-2,6-bis(thiocarboxylic acid) (PDTC) may also provide producing organisms with the ability to assimilate other divalent transition metals. This was tested further by examining regulation of siderophore production, expression of pdt genes, and growth in response to added zinc. In media containing 10-50 microM ZnCl2, the production of PDTC was found to be differentially repressed, as compared with the production of pyoverdine.

Identification and characterization of Pseudomonas membrane transporters necessary for utilization of the siderophore pyridine-2,6-bis(thiocarboxylic acid) (PDTC).

The compound pyridine-2,6-bis(thiocarboxylic acid) (PDTC) is known to be produced and excreted by three strains of Pseudomonas. Its reactivity includes the complete dechlorination of the environmental contaminant carbon tetrachloride. PDTC functions as a siderophore; however, roles as a ferric reductant and antimicrobial agent have also been proposed.

Transcriptional regulation of the pdt gene cluster of Pseudomonas stutzeri KC involves an AraC/XylS family transcriptional activator (PdtC) and the cognate siderophore pyridine-2,6-bis(thiocarboxylic acid).

In order to gain an understanding of the molecular mechanisms dictating production of the siderophore and dechlorination agent pyridine-2,6-bis(thiocarboxylic acid) (PDTC), we have begun characterization of a gene found in the pdt gene cluster of Pseudomonas stutzeri KC predicted to have a regulatory role. That gene product is an AraC family transcriptional activator, PdtC. Quantitative reverse transcription-PCR and expression of transcriptional reporter fusions were used to assess a role for pdtC in the transcription of pdt genes.

Comparison of bacterial communities in New England Sphagnum bogs using terminal restriction fragment length polymorphism (T-RFLP).

Wetlands are major sources of carbon dioxide, methane, and other greenhouse gases released during microbial degradation. Despite the fact that decomposition is mainly driven by bacteria and fungi, little is known about the taxonomic diversity of bacterial communities in wetlands, particularly Sphagnum bogs. To explore bacterial community composition, 24 bogs in Vermont and Massachusetts were censused for bacterial diversity at the surface (oxic) and 1 m (anoxic) regions.

Bioremediation of soils contaminated with explosives.

The large-scale industrial production and processing of munitions such as 2,4,6-trinitrotoluene (TNT) over the past 100 years led to the disposal of wastes containing explosives and nitrated organic by-products into the environment. In the US, the Army alone has estimated that over 1.2 million tons of soil have been contaminated with explosives, and the impact of explosives contamination in other countries is of similar magnitude.

Physiological and molecular genetic evaluation of the dechlorination agent, pyridine-2,6-bis(monothiocarboxylic acid) (PDTC) as a secondary siderophore of Pseudomonas.

The bacterial metabolite and transition metal chelator pyridine-2,6-dithiocarboxylic acid (PDTC), promotes a novel and effective means of dechlorination of the toxic and carcinogenic pollutant, carbon tetrachloride. Pyridine-2,6-dithiocarboxylic acid has been presumed to act as a siderophore in the Pseudomonas strains known to produce it. To explore further the physiological function of PDTC production, we have examined its regulation, the phenotype of PDTC-negative (pdt) mutants, and envelope proteins associated with PDTC in P.

Metal chelating properties of pyridine-2,6-bis(thiocarboxylic acid) produced by Pseudomonas spp. and the biological activities of the formed complexes.

We evaluated the ability of pyridine-2,6-bis(thiocarboxylic acid) (pdtc) to form complexes with 19 metals and 3 metalloids. Pdtc formed complexes with 14 of the metals. Two of these metal:pdtc complexes, Co:(pdtc)2 and Cu:pdtc, showed the ability to cycle between redox states, bringing to 4 the number of known redox-active pdtc complexes.