| Abstract: | Chlorella pyrenoidosa, a green alga which has no measurable Ca requirement, tolerated much higher Al concentrations in solution than higher plants which require considerable Ca. This alga also gave significant positive yield responses to Al concentrations between 1.5 and 12 ppm (added at pH 4.6). The positive Al response was not attributable to V, Cr, Ni, Co, W, or Ti contaminants in the Al salt. A strain of C. pyrenoidosa having even greater Al tolerance was isolated, by subjecting the original Strain I (Fitzgerald) culture to increasing Al stress. This strain, I-Al, grew in stagnant cultures containing 48 ppm Al at an initial pH of 4.2. Its yield also was not significantly decreased by 48 ppm Al in aerated cultures when both inoculum and solution pH were 4.6. Under the same conditions the original Strain I organism was injured by 3 and 6 ppm Al and was killed by 12 ppm. Algal strains which differ in Al tolerance may be useful in (1) studies on the mechanism of Al toxicity and mineral nutrition in general; and (2) in raising the pH, precipitating Al, and thereby detoxifying Al-containing acid mine drainage water and commercial wastes. |
