Iron Acquisition in Cynobacteria Synechococcus sp. PCC 7002 Culture
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- Institutt for kjemi 
Iron is an essential micronutrient for the growth and health of phytoplankton and low overall iron concentrations in the High Nutrient Low Chlorophyll (HNLC) zones in the ocean have been reported. Cyanobacteria is one of the most important organism involved in primary productivity and iron-limitation could indirectly affect the global carbon cycle and CO2 sequestration. This project aims to study the influence of the type of iron mineral and iron acquisition mechanism efficiency in Cyanobacteria. Two incubation experiments were carried out using a tropical strain of Synechococcus sp. PCC 7002 at room temperature (25 °C). Two different forms of Fe were used in cultures with different solubilities; one culture was added with 50 nM FeCl3 (74.4 g/100 mL) and the other culture was added with 50 nM Goethite (FeO(OH)) (HCl soluble), respectively. Biological parameters such as growth and chlorophyll a concentration as well as particulate and intracellular Fe were analysed. Growth of Synechococcus sp. PCC 7002 was significantly slow in both cultures regardless of Fe concentrations which was predicted to be due to cells already being in stationary phase during the sampling period. High particulate and intracellular Fe were detected in FeCl3 culture and no physiological stress response was observed. On the other hand, cells grown in FeO(OH), had less particulate and intracellular Fe however, the days where intracellular Fe was recorded, the Fe concentration was high. Overall, this study suggests that FeCl3 is more available to cells than the less soluble goethite FeO(OH) and the cells grown in FeO(OH) culture are able to utilise the particulate Fe via PilA1 mechanism. However, future work must be carried out in order to conclude the experiment.