23 research outputs found
Thiobacillus plumbophilus spec. nov., a novel galena and hydrogen oxidizer
From an uranium mine three strains of rodshaped, mesophilic, chemolithoautotrophic bacteria were isolated. They grow by oxidation of H2S, galena (PbS) and H2. Anglesite (PbSO4) is formed from galena. No ferrous iron is oxidized by the isolates. They grow between pH 4 and 6.5 at temperatures of about 9 to 41°C (optimum around 27°C). The G+C content of the DNA is around 66 mol %. Based on their ability to oxidize sulfur compounds, the new organisms belong to the genus Thiobacillus. No significant homology with Thiobacillus ferrooxidans and Thiobacillus cuprinus was detected by DNA-DNA hybridization. Therefore the new isolates represent a new species within the genus Thiobacillus. Based on the unusual growth on galena, we name the new species Thiobacillus plumbophilus (type strain Gro 7; DSM 6690)
Phytoremediation of petroleum hydrocarbon-contaminated soils with two plant species: Jatropha curcas
Integration of Metal-Resistant Determinants from the Plasmid of an Acidocella Strain into the Chromosome of Escherichia coli DH5a
Acidophilic bacteria of mine origin are ideal systems for studying microbial metal resistance
because of their ability to grow in the presence of high concentrations of metal salts. We have previously
shown that the metal-resistant transformants obtained after transformation of Escherichia coli DH5a
with plasmid DNA preparation from Acidocella sp. strain GS19h did not contain any plasmid suggesting
chromosomal integration of the plasmid(s) (Appl Environ Microbiol 1997; 63: 4523–4527). The present
study provides evidence in support of this suggestion. The pulsed field gel electrophoresis (PFGE)
pattern of genomic DNA of the plasmidless metal-resistant transformants differed markedly from that of
the untransformed DH5a strain. Moreover, when the recombinant plasmids constructed by cloning
plasmid DNA fragments of the Acidocella strain GS19h in the vector pBluescript II KS+ were used to
transform E. coli DH5a strain, no plasmid DNA was detected in some of the zinc- and ampicillinresistant
(ZnrAmpr) clones. The PFGE pattern of genomic DNA of such a transformed clone also
differed markedly from that of the parent strain, suggesting chromosomal integration of the recombinant
plasmid(s) containing both ampicillin- and zinc-resistance determinants. This observation was further
supported by hybridization of chromosomal DNA of the plasmidless ZnrAmpr E. coli DH5a clone with
the probes made from the plasmid DNA of strain GS19h and the vector DNA. Thus, this study corroborates
our previous finding and documents the phenomenon of integration of metal-resistant determinants
from the Acidocella GS19h plasmid(s) into the chromosome of E. coli DH5