Carotenoids and pH of the culture medium play an important role in displaying metal stress in batch and semi-continuous cultures ofAnabaena doliolum
Annales de Limnologie
We analysed the responses of Anabaena doliolum to elevated levels of copper and zinc in batch and semi-continuous cultures. Approximately 10, 4 and 8 and 5-times greater inhibition in final yield of A. doliolum occurred at 1, 2 mM Cu and 2.5 and 5 mM of Zn, respectively, in semi-continuous culture in comparison to batch culture. Protein, chlorophyl a and carotenoid contents of A. doliolum showed significantly (P < 0.05) higher inhibition by test metals in semi-continuous culture than in batch
... ure than in batch culture. The greater sensitivity of different parameters of the test organism was related to the high metal content of the cells grown in semi-continuous system. Moreover, enhancement of pH of the culture suspension in batch culture showed a negative relationship with metal accumulation, and therefore with toxicity. This was due to decrease in free ionic concentrations of test metals. Carotenoids acted as a metal detoxifying agent by minimizing metal-induced inhibition in batch culture as was evident from its negative relationship with metal toxicity.