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Resistance of Cyanobacteria (Synechococcus SP. PCC 7002) to Sulfide compound

Synechococcus sp. PCC7002 was cultured in the medium A2, a modification of Stevens et al. (1973) on a rotary shaker (100 rpm). The initial concentration of cells is controlled to an OD730 of 0.1 in fresh medium. Different concentration of sodium sulfide is added, and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) was put into experimental group. Cells are grown in the six-well-plates and monitored under OD730 every 24 hour.

Synechococcus sp. PCC7002 was cultured in the medium A2, rotary shaker and initial cell concentration are the same as the last experiment. DCMU is diluted with A2 medium into different concentration, and 10 mM of sodium sulfide is added to the experimental group. The measurement method and frequency of cell growth has been described previously.

With the result of previous experiment, the concentration of both sodium sulfide and DCMU is adjusted. Sodium sulfide is diluted from 40mM to 2.5mM, while DCMU 0.5 μM is added into the experimental group.

In this experiment, we aimed to examine whether the sqr Synechococcus SP. PCC 7942 expressed is functional. Synechococcus SP. PCC 7942 with sqr and wild type was cultivated in BG-11 medium (Allen M.M. 1968) on the same rotary shaker described in the first experiment. Initial cell concentration is fixed to an OD730 of 0.1 in the medium. 2.5mM of sodium sulfide is added into the experimental group, and DCMU is diluted from 1μM to 0.5μM.

From the last experiment, we found it necessary to perform another independent experiment to find the optimal DCMU concentration of Synechococcus SP. PCC 7942. In addition, the initial cell concentration was adjusted to an OD730 of 0.2 in BG-11 medium. DCMU is diluted from 1μM to 0.125μM. Except of cell concentration, all condition remained the same for both sqr and wild type strain of Synechococcus SP. PCC 7942.

In this experiment, the BG-11 medium is used and the initial cell concentration is adjusted to an OD 730 of 0.2 as the last test. In addition, the sodium sulfide is diluted from 5mM to 5/16mM, while DCMU 0.25μM is added to every well.

With the result of previous experiment, the concentration of both sodium sulfide and DCMU is adjusted. Sodium sulfide is diluted from 40mM to 2.5mM, while DCMU 0.5 μM is added into the experimental group.