The capacity of growing algal cells to affect the pH and the buffering properties of the medium

摘要

Supernatants from cultures of green high-temperature algae,Chlorella7-11-05 andStichococcus6-17-35, were used to obtain titration curves and to calculate buffer indexes (β). It was generally observed that the peak of buffering activity in growing cultures shifted to the pH characteristic of the pK of the newly generated buffer(s). Depending on the experimental conditions and the age of the culture, the buffering capacity at its peak increased up to 4–5 times of the value for the original medium. Buffering capacity of algal cells was demonstrated for both strains grown in the media originally buffered either with phosphate or with Tris and for cultures of different ages including those of the young synchronized cells. The capacity of growing cells to drastically affect the pH and/or the buffering characteristics of the medium indicates that the role of the buffer originally employed in a particular medium may often extend for a relatively short period of time after which the buffer system(s) produced by the cells play a more important pa