Hexavalent chromium uptake by sensitive and tolerant mutants of Schizosaccharomyces pombe.
Lysine and leucine auxotrophic, heterothallic (h+, h-) strains of Schizosaccharomyces pombe were used to obtain chromium (VI)-sensitive and -tolerant mutants by ultraviolet radiation-induced and nitrosoguanidine-induced mutagenesis. The minimal inhibitory concentrations of K2Cr2O7 on YEA media were 225 microM for the wild-type strain CW-6, 125 microM for the sensitive mutant CS-6.51 and 275 microM for the tolerant mutant CT-6.66. The mutants exhibited cross-sensitivity of various patterns to Cd2+, Cu2+, Ni2+, Zn2+ and VO3-(4). Cr(VI) was added to the actively growing cultures and the total chromium (TOCr) content of the cells was determined. The sensitive mutant exhibited a high bioaccumulation ability, with a dry biomass of 810 micrograms g-1 after 30 min, while the tolerant mutant had a significantly lower ability than the wild-type strain. In PIPES buffer, washed, lysine-starved biomasses were treated with 75 microM Cr(VI) and after 2 h, the TOCr and the organically bound chromium (OBCr) were determined. Under these conditions, the sensitive and tolerant mutants had the same TOCr content, 50% of which was OBCr. The wild-type strain exhibited a lower TOCr content than that of its mutants and only 35% of this was OBCr. The Cr(VI)-sensitivity was due to a significantly increased uptake of Cr(VI).
Czakó-Vér
K
K
Department of Genetics and Microbiology, Janus Pannonius University, Pécs, Hungary.
Batiè
M
M
Raspor
P
P
Sipiczki
M
M
Pesti
M
M
D002857:Chromium / Q000378:metabolism*; D019216:Metals, Heavy / Q000494:pharmacology; D016296:Mutagenesis / Q000187:drug effects / Q000528:radiation effects; D009604:Nitrosoguanidines / Q000494:pharmacology; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014466:Ultraviolet Rays
D019216:Metals, Heavy; D009604:Nitrosoguanidines; D002857:Chromium; C074702:chromium hexavalent ion