Differential responses of a mine tailings Pseudomonas isolate to cadmium and lead exposures.
We examined cadmium and lead resistance in Pseudomonas sp. S8A, an isolate obtained from mine tailings-contaminated soil. Resistant to soluble metal concentrations up to 200 mg l(-1) cadmium and 300 mg l(-1) lead, S8A produced both exopolymer and biosurfactant. Upon growth, this pseudomonad diverged into two morphologically distinct colony subtypes; small and round or large and flat. In the presence of lead and in the no metal control the large morphotype appeared only in late stationary phase. With cadmium the large morphotype appeared immediately following exposure. Results show that the large morphotype produced greater amounts of surfactant than the small morphotype, suggesting a unique subpopulation response to cadmium toxicity. Results also indicate that an unidentified 28 kDa protein was expressed following exposure to >10 mg l(-1) cadmium. This study demonstrates new links between surfactant production, differential subpopulation response and metal exposure.
Department of Biology, University of Colorado at Denver, Denver, USA.
Duried M
DM
Kassab
Timberley M
TM
Roane
D001673:Biodegradation, Environmental; D002104:Cadmium / Q000737:chemistry / Q000378:metabolism*; D004781:Environmental Exposure; D004784:Environmental Monitoring; D007854:Lead / Q000378:metabolism*; D008670:Metals; D010957:Plasmids / Q000378:metabolism; D011108:Polymers / Q000737:chemistry; D011549:Pseudomonas / Q000378:metabolism*; D012987:Soil; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry; D013997:Time Factors
D008670:Metals; D011108:Polymers; D012987:Soil; D012989:Soil Pollutants; D013501:Surface-Active Agents; D002104:Cadmium; D007854:Lead