Abstract
In order to clarify the effect of the manganese released from lake sediment on the growth of M. aeruginosa, the cyanobacterium was cultured with leachate obtained by column leaching experiments which used lake sediment in Lake Kasumigaura Japan. The growth of M. aeruginosa in the leachate of sediment at St.1 and St.9 reached the density higher than 1.2×106 cells⋅ml-1, and was larger than those at the other points. The corresponding manganese concentrations of these leachates were also more than 10 times higher than the other points. That is why, it was considered that manganese might promote the growth of M. aeruginosa. Furthermore, in order to clarify the relation between manganese and the growth of M. aeruginosa, it was cultured with the addition of manganese into leachates of sediment and artificial medium. From the results, the addition of manganese or EDTA in all leachates of sediment except those for St.l and St.9, also accelerated the growth of M. aeruginosa. Moreover, it was obvious that manganese only promoted the growth of M. aeruginosa in the presence of EDTA, according to the results of experiments with artificial medium. A comparison of the results of experiments with leachate of sediment and artificial medium indicated that manganese complexing-agents like EDTA were included in the leachate of sediment. The relation between manganese and complexing-agents released from sediment is thus important for controlling the growth of M. aeruginosa in eutrophic lake.
