Nice observation. I am not a specialist on metal toxicity, so the following
may be completely wrong.
Might the augmented copper toxicity in glucose cultures be due to a more
reducing environment (faster growth than on galactose, lower dissolved
oxygen)?. Cu+ is more toxic than Cu2+ (see Pubmed abstract below). Glucose
repression of mechanisms involved in copper tolerance might be another
Jack Pronk, Delft
Ciba Found Symp 1980;79:301-18
Anaerobic potentiation of copper toxicity and some environmental
The toxicity of copper is substantially greater when the metal ions is
applied to cells under conditions of anoxia than under aerobic conditions.
The increase in toxicity occurs because Cu(II) is reduced to Cu(I) which is
stable under anoxia and is more toxic than the oxidized species. This effect
has been observed in mammalian cells in tissue culture and in bacteria.
Anoxic potentiation of copper toxicity has also been observed in algal,
fungal and yeast cells. The reduction of Cu(II) has been demonstrated by
electron paramagnetic resonance spectrometry. The appearance of Cu(I) has
been observed by means of specific colorimetric reagent. The reduction of
Cu(II) to Cu(I) is not dependent upon concomitant metabolism and requires
only a supply of sulphydryl groups. Microorganisms that are responsible for
two anaerobic processes of economic importance to humans, the digestion of
sewage sludge in effluent treatment plants and the digestion of food in
ruminant animals, may be exposed to high concentrations of copper. The
environmental consequences of this exposure are discussed.
PMID: 6258886, UI: 81137578
Yevgeniya Romanovna Lapik heeft geschreven in bericht
<73hpne$84v at net.bio.net>...
>>I'm looking for an information about S.cerevisiae growth on a galactose
>media containing copper. I'm using SG + 0.5mM CuSO4 media and it looks
>like that copper is significantly less toxic to yeast cells in the
>than in the glucose background (SD + 0.5mM CuSO4), but I wasn't able to
>find any information on this subject. Does anybody know anything about