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The bacterial plasmid pEMT8 contains the tfdA gene that encodes the 2,4-dichlorophenoxyacetic acid (2,4-D):alpha-ketoglutaric acid dioxygenase (TfdA) involved in 2,4-D degradation. The tfdA gene is 94% similar to that of the Burkholderia sp. strain RASC and has somewhat less similarity to that present on the Alcaligenes eutrophus pJP4 plasmid. No genes similar to the tfdB and tfdCDEF are present on pEMT8. The pEMT8 plasmid is captured by genetic complementation of transconjugates of A. eutrophus containing a pJP4 plasmid lacking the tfdA gene and bacteria from the soil.

UV inactivation of E. coli in a plug flow reactor between concentric cylinders was investigated. The concentration boundary layer thickness was computed for laminar, turbulent and Taylor-Couette flow in terms of the respective mass transfer Sherwood number. It is demonstrated that the concentration boundary layer is thin and that the mass transfer coefficient is large and comparable in size for both turbulent and laminar Taylor-Couette flow in contrast to laminar flow. Computation of the fluence distribution for each flow pattern indicate that turbulent and especially Taylor-Couette flow subject E. coli to an equal flux of photons corresponding to ideal plug flow. However, experiments with turbulent flow that require large axial velocities indicate that very long reactor lengths are necessary to inactivate E. coli. Finally, rotor wavy wall modifications are explored to increase the inactivation of microorganisms in Taylor-Couette flow. [ABSTRACT FROM AUTHOR]

Reports on the measurement for multiwire thermocouples consisting of either two or three wires of unequal diameters. Recording of the signals from multiwire probe; Demonstration that the reconstructed signal from the multiwire thermocouple requires no compensation; Significance of the Fourier transformed data from the wires.

Describes the performance of a novel three-wire thermocouple of unequal diameters that does not require compensation at lower fluid temperature frequencies. Natural frequency of the single wire; Determination of gas temperature; Temperature profiles for the ambient gas and the three type-K thermocouple wires.

The complete 64 508 bp nucleotide sequence of the IncP-1β antibiotic-resistance plasmid pB10, which was isolated from a waste-water treatment plant in Germany and mediates resistance against the antimicrobial agents amoxicillin, streptomycin, sulfonamides and tetracycline and against mercury ions, was determined and analysed. A typical class 1 integron with completely conserved 5' and 3' segments is inserted between the tra and trb regions. The two mobile gene cassettes of this integron encode a β-Iactamase of the oxacillin-hydrolysing type (Oxa-2) and a gene product of unknown function (OrfE-like), respectively. The pB10-specific gene load present between the replication module (trfA1) and the origin of vegetative replication (oriV) is composed of four class II (Tn3 family) transposable elements: (i) a Tn501-like mercury-resistance (mer) transposon downstream of the trfA1 gene, (ii) a truncated derivative of the widespread streptomycin-resistance transposon Tn5393c, (iii) the insertion sequence element IS 1071 and (iv) a Tn 1721-like transposon that contains the tetracycline-resistance genes tetA and tetR. A very similar Tn501-like mer transposon is present in the same target site of the IncP-1β degradative plasmid pJP4 and the IncP-1β resistance plasmid R906, suggesting that pB10, R906 and pJP4 are derivatives of a common ancestor. Interestingly, large parts of the predicted pB10 restriction map, except for the tetracycline-resistance determinant, are identical to that of R906. It thus appears that plasmid pB10 acquired as many as five resistance genes via three transposons and one integron, which it may rapidly spread among bacterial populations given its high promiscuity. Comparison of the pB10 backbone DNA sequences with those of other sequenced IncP-1β plasmids reveals a mosaic structure. While the conjugative transfer modules (trb and tra regions) and the replication module are very closely related to the corresponding segments of the IncP-1β resistance plasmid R751 and even more similar to the IncP-1β degradative plasmids pTSA and pADP-1, the stable inheritance operons klcAB-korC and kleAEF are most similar to those of the IncP-1β resistance plasmid pB4, and clearly less similar to the other IncP-1β plasmids. This suggests that IncP-1β plasmids can undergo recombination in the environment, which may enhance plasmid diversity and bacterial adaptability. [ABSTRACT FROM AUTHOR]

The number, spatial distribution, and significance of genetically distinguishable ecotypes of prokaryotes in the environment are poorly understood. Oda et al. (Y. Oda, B. Star, L. A. Huisman, J. C. Gottschal, and L. J. Forney, Appl. Environ. Microbiol. 69:xxx-xxx, 2003) have shown that Rhodopseudomonas palustris ecotypes were lognormally distributed along a 10-m transect and that multiple strains of the species could coexist in 0.5-g sediment samples. To extend these observations, we investigated the clonal diversity of R. palustris in 0.5-g samples taken from the corners and center of a 1-m square. A total of 35 or 36 clones were recovered by direct plating from each sample and were characterized by BOX AIR repetitive element-PCR genomic DNA fingerprinting. Isolates with fingerprint images that were ≥80% similar to each other were defined as the same genotype. Among the 178 isolates studied, 32 genotypes were identified, and each genotype contained between 1 and 40 isolates. These clusters were consistent with minor variations found in 16S rRNA gene sequences. The Shannon indices of the genotypic diversity within each location ranged from 1.08 (5 genotypes) to 2.18 (13 genotypes). Comparison of the rank abundance of genotypes found in pairs of locations showed that strains from three locations were similar to each other, with Morisita-Horn similarity coefficients ranging from 0.59 to 0.71. All comparisons involving the remaining two locations resulted in coefficients between 0 and 0.12. From these results we inferred that the patterns of ecotype diversity at the sampling site are patchy at a 1-m scale and postulated that factors such as mixing, competitive interactions, and microhabitat variability are likely to be responsible for the maintenance of the similarities between some locations and the differences between others. [ABSTRACT FROM AUTHOR]