Microbial communities in subpermafrost saline fracture water at the Lupin Au mine, Nunavut, Canada.

We report the first investigation of a deep subpermafrost microbial ecosystem, a terrestrial analog for the Martian subsurface. Our multidisciplinary team analyzed fracture water collected at 890 and 1,130 m depths beneath a 540-m-thick permafrost layer at the Lupin Au mine (Nunavut, Canada). 14C, 3H, and noble gas isotope analyses suggest that the Na-Ca-Cl, suboxic, fracture water represents a mixture of geologically ancient brine, approximately25-kyr-old, meteoric water and a minor modern talik-water component.

Simultaneous transport of two bacterial strains in intact cores from Oyster, Virginia: biological effects and numerical modeling.

The transport characteristics of two adhesion-deficient, indigenous groundwater strains, Comamonas sp. strain DA001 and Erwinia herbicola OYS2-A, were studied by using intact sediment cores (7 by 50 cm) from Oyster, Va. Both strains are gram-negative rods (1.

Relative dominance of physical versus chemical effects on the transport of adhesion-deficient bacteria in intact cores from South Oyster, Virginia.

Bacterial transport experiments were conducted using intact sediment cores collected from sites on the Delmarva Peninsula near South Oyster, VA, to delineate the relative importance of physical and chemical heterogeneity in controlling transport of an adhesion-deficient bacterial strain. Electron microscopy revealed that the sediments consisted of quartz and feldspar with a variable amount of clay and iron and aluminum hydroxide coatings on the grains. A nonmotile, gram-negative indigenous groundwater strain, designated as Comamonas sp.

Development of a vital fluorescent staining method for monitoring bacterial transport in subsurface environments.

Previous bacterial transport studies have utilized fluorophores which have been shown to adversely affect the physiology of stained cells. This research was undertaken to identify alternative fluorescent stains that do not adversely affect the transport or viability of bacteria. Initial work was performed with a groundwater isolate, Comamonas sp.

Effect of novel biosurfactants on biodegradation of polychlorinated biphenyls by pure and mixed bacterial cultures.

A study was conducted to determine the potential positive effect of novel biosurfactants on the enhancement of Aroclor 1248 metabolization in both in vitro and in situ experiments. Among two lipopeptides tested the highest activity was found in experiments with a hydrolytically opened form of lichenysin A. Lichenysin A itself did not enhance the degradation activity of chosen microorganism-degraders and in most cases inhibited their PCB mineralization rates.

Nucleotide sequence and initial functional characterization of the clcR gene encoding a LysR family activator of the clcABD chlorocatechol operon in Pseudomonas putida.

The 3-chlorocatechol operon clcABD is central to the biodegradative pathway of 3-chlorobenzoate. The clcR regulatory gene, which activates the clcABD operon, was cloned from the region immediately upstream of the operon and was shown to complement an insertion mutation for growth on 3-chlorobenzoate. ClcR activated the clcA promoter, which controls expression of the clcABD operon, in trans by 14-fold in an in vivo promoter probe assay in Pseudomonas putida when cells were incubated with 15 mM 3-chlorobenzoic acid.

Roles of CatR and cis,cis-muconate in activation of the catBC operon, which is involved in benzoate degradation in Pseudomonas putida.

In Pseudomonas putida, the catBC operon encodes enzymes involved in benzoate degradation. Previous studies have determined that these enzymes are induced when P. putida is grown in the presence of benzoate.

Functional analysis of the Pseudomonas putida regulatory protein CatR: transcriptional studies and determination of the CatR DNA-binding site by hydroxyl-radical footprinting.

CatR, a LysR family protein, positively regulates the Pseudomonas putida catBC operon, which is required for growth on benzoate as a sole carbon source. Transcriptional studies show that the catR and catBC promoters are divergent and overlapping by 2 bp. A beta-galactosidase promoter probe vector was constructed to analyze expression from the catR and catBC promoters under induced and uninduced conditions.

Alginate synthesis by Pseudomonas aeruginosa: a key pathogenic factor in chronic pulmonary infections of cystic fibrosis patients.

Pulmonary infection by mucoid, alginate-producing Pseudomonas aeruginosa is the leading cause of mortality among patients suffering from cystic fibrosis. Alginate-producing P. aeruginosa is uniquely associated with the environment of the cystic fibrosis-affected lung, where alginate is believed to increase resistance to both the host immune system and antibiotic therapy.

Purification and characterization of phosphomannose isomerase-guanosine diphospho-D-mannose pyrophosphorylase. A bifunctional enzyme in the alginate biosynthetic pathway of Pseudomonas aeruginosa.

We report here the purification and characterization of phosphomannose isomerase-guanosine 5'-diphospho-D-mannose pyrophosphorylase, a bifunctional enzyme (PMI-GMP) which catalyzes both the phosphomannose isomerase (PMI) and guanosine 5'-diphospho-D-mannose pyrophosphorylase (GMP) reactions of the Pseudomonas aeruginosa alginate biosynthetic pathway. The PMI and GMP activities co-eluted in the same protein peak through successive fractionation on hydrophobic interaction, ion exchange, and gel filtration chromatography. The purified enzyme migrated as a 56,000 molecular weight protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the native protein migrated as a monomer of 54,000 molecular weight upon gel filtration chromatography.

Nucleotide sequencing and characterization of Pseudomonas putida catR: a positive regulator of the catBC operon is a member of the LysR family.

Pseudomonas putida utilizes the catBC operon for growth on benzoate as a sole carbon source. This operon is positively regulated by the CatR protein, which is encoded from a gene divergently oriented from the catBC operon. The catR gene encodes a 32.

Identification of nucleotides critical for activity of the Pseudomonas putida catBC promoter.

Pseudomonas putida utilizes the catBC operon, which encodes cis,cis-muconate lactonizing enzyme I (MLEI; EC 5.5.1.

Mutational analysis of the lac regulatory region: second-site changes that activate mutant promoters.

Second-site mutations that restored activity to severe lacP1 down-promoter mutants were isolated. This was accomplished by using a bacteriophage f1 vector containing a fusion of the mutant E. coli lac promoters with the structural gene for chloramphenicol acetyltransferase (CAT), so that a system was provided for selecting phage revertants (or pseudorevertants) that conferred resistance of phage-infected cells to chloramphenicol.