The production of 2-methylisoborneol (MIB) by Oscillatoriatenuis Agardh often causes taste and odor problems in tap water supplied from Lake Biwa. In order to understand growth characteristics of O. tenuis, the alga was cultured under several different conditions. The maximum biomass observed in culture was about 2000 filaments/ml, whereas the standing crop measured in the lake was as low as 32 filaments/ml. The optimum temperature and pH were 25-30 C and 8-9, respectively. The concentrations of nitrogen and phosphorus which were optimum for growth in the medium were 0.31 mg/l and 0.08 mg/l and above, respectively. The concentrations of these elements in the lake were almost equal to those resulting in optimum growth. Growth of the alga was suppressed when the alga was grown in the culture medium from which chelated iron was removed. The total concentration of iron in lake water was sufficient for the algal growth; however, the concentration of soluble iron, which is available for the alga, was lower than in CT-medium. Addition of 0.03 mg/l EDTA to lake water promoted the algal growth invitro, while 3 mg/l EDTA suppressed the growth. The difference between growth under culture conditions and that in the lake may be due to the difference in the concentration of soluble iron.
Verification of Suitability of Fly-Ash-Shell Blocks for Algal Growth: Understanding Growth Characteristics of Periphytic Diatoms by Using Non-Distractive Measurement Method