Affiliation:
1. Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352
Abstract
ABSTRACT
The toxicity of Al to
Desulfovibrio desulfuricans
G20 was assessed over a period of 8 weeks in a modified lactate C medium buffered at four initial pHs (5.0, 6.5, 7.2, and 8.3) and treated with five levels of added Al (0, 0.01, 0.1, 1.0, and 10 mM). At pH 5, cell population densities decreased significantly and any effect of Al was negligible compared to that of the pH. At pHs 6.5 and 7.2, the cell population densities increased by 30-fold during the first few days and then remained stable for soluble-Al concentrations of <5 × 10
−5
M. In treatments having total-Al concentrations of ≥1 mM, soluble-Al concentrations exceeded 5 × 10
−5
M and limited cell population growth substantially and proportionally. At pH 8.3, soluble-Al concentrations were below the 5 × 10
−5
M toxicity threshold and cell population density increases of 20- to 40-fold were observed. An apparent cell population response to added Al at pH 8.3 was attributed to the presence of large, spirilloidal bacteria (accounting for as much as 80% of the cells at the 10 mM added Al level). Calculations of soluble-Al speciation for the pH 6.5 and 7.2 treatments that showed Al toxicity suggested the possible presence of the Al
13
O
4
(OH)
24
(H
2
O)
12
7+
“tridecamer” cation and an inverse correlation of the tridecamer concentration and the cell population density. Analysis by
27
Al nuclear magnetic resonance spectroscopy, however, yielded no evidence of this species in freshly prepared samples or those taken 800 days after inoculation. Exclusion of the tridecamer species from the aqueous speciation calculations at pHs 6.5 and 7.2 yielded inverse correlations of the neutral Al(OH)
3
and anionic Al(OH)
4
−
monomeric species with cell population density, suggesting that one or both of these ions bear primary responsibility for the toxicity observed.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
43 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献