Characterization of Heavy-Metal-Removal Bacteria From The Persian Gulf
The study was carried out to isolate and screen high heavy metals resistant bacteria from Persian Gulf and enclosed industrial areas within 241,000 km2. A total of 35 heavy metal resistant bacteria strains were identified from sediment and water samples collected. The resistance and biological ca...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English English |
| Published: |
2005
|
| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/6594/1/FPV_2005_2.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | The study was carried out to isolate and screen high heavy metals resistant
bacteria from Persian Gulf and enclosed industrial areas within 241,000 km2. A
total of 35 heavy metal resistant bacteria strains were identified from sediment
and water samples collected. The resistance and biological capacity of the isolated
bacteria were tested in a new formulated media, minimal salt solution (M.S.S),
that mimics seawater. Isolated bacteria responded to media supplemented in range
0.5 to 2 mM of Zn, Cd, Cu and Pb by showing a prolonged lag phase and by
decreasing growth rate.
Bacteria isolates, in the form of free or immobilized cells, are able to remove lead,
copper, zinc and cadmium from solution. Removal of lead and cadmium from
solution by some bacteria was very efficient, about 120 mglg dry weight as high
as 90%. Isolates tested presented distinct uptake capacities and the best results
were obtained for Delftia tsuruhatensis and Pseudornonas AU3411 respectively.The diversity of isolated bacteria was examined by the phylogenetic analysis of
16s rRNA gene sequences. The phylogenetic analyses of the sequences revealed
seven main taxonomic lineages. The phylogenetic tree illustrated discrimination
between isolated bacteria from wastewater, industrials areas and marine
environment. Some Pseudornonas strains isolated from marine environment were
well differentiated from those of industrial wastewater. Members of the genera
Delftia and Bacterium formed a monophyletic group within the subdivision of the
class. There was a clear differentiation between two groups of Pseudornonas and
other groups of bacteria in the phylogenetic tree.
The isolated bacteria were tested for the occurrence of plasmid using the modified
alkaline lysate method. The study revealed that the frequency of the occurrence of
plasmid in the heavy metals resistance bacteria was more than in the common
bacteria. Multiple forms of plasmids were observed in 66% of the plasmidcarrying
strains. Isolates bacteria from industrials wastewater showed the highest
plasmid incidence (84.6%). In the marine environment there was a slightly higher
incidence of plasmid in bacteria isolated from sediments (55.5%) compared to the
water sample of the same origin (53.8%).
Scanning Electron Microscope (SEM) analyses showed Pseudornonas sp.
accumulated heavy metals in the cell wall and along the external cell surfaces.
This suggested that heavy metals uptake involves both surface phenomena and
diffusion. Energy Dispersive X-ray (EDX) analysis confirmed heavy metals on
the bacteria cell surface which was reported by SEM. |
|---|