Publication: The role of exopolymers in protection of Ralstonia sp., a cadmium-resistant bacterium, from cadmium toxicity
3
Issued Date
2008
Resource Type
Language
eng
ISSN
1906-1714
Rights
Mahidol University
Rights Holder(s)
Thai Society of Higher Education Institutes on Environment
Bibliographic Citation
EnvironmentAsia. Vol.2, (2008), 37-42.
Suggested Citation
Anchulee Watcharamusika, Benjaphorn Prapagdee, Patana Thavipoke, Narin Boontanon, เบญจภรณ์ ประภักดี, พัฒน ทวีโภค, นรินทร์ บุญตานนท์ The role of exopolymers in protection of Ralstonia sp., a cadmium-resistant bacterium, from cadmium toxicity. EnvironmentAsia. Vol.2, (2008), 37-42.. Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/48735
Research Projects
Organizational Units
Authors
Journal Issue
Thesis
Title
The role of exopolymers in protection of Ralstonia sp., a cadmium-resistant bacterium, from cadmium toxicity
Abstract
Production of exopolymers is one of heavy metal resistance mechanisms in bacteria. Ralstonia sp. TAK1, a cadmiumresistant
bacterium, was isolated from a high cadmium (Cd) contaminated soil at the zinc mine, Tak province, Thailand. The
bacterium was cultivated in LB broth and its growth was monitored. The yields of exopolymers were measured by the
phenol-sulfuric method at different growth phases. The levels of Cd resistance were quantitatively determined by survival
cell assay. The highest amount of exopolymers (0.69 mg glucose equivalent/ mg dry weight) was found at the stationary
phase and sharply decreased at the late-stationary phase. In addition to high production of exopolymers at the stationary
phase, Ralstonia sp. TAK1 was more resistant to Cd than that of exponential phase cells. These results suggested that the
resistance to Cd toxicity in Ralstonia sp. TAK1 at the stationary phase is mediated by exopolymer production. Contradictorily,
there was no correlation between Cd resistance level and exopolymer production of cells at exponential phase indicating
that other mechanism(s) is responsible for Cd resistance of exponential phase cells. In addition, 0.4 mM CdCl2 was able to
induce the increasing of exopolymers at the mid-exponential phases compared to uninduced cells. Exopolymer production
of Cd-induced cells was constant from the mid-stationary to late-stationary phase. However, the highest exopolymers was
found in uninduced cells at the stationary phase.