Phototactic motility of Synechocystis Sp. uniwg from brackish environment

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dc.contributor.authorToh, Pamela Shi Ying
dc.date.accessioned2014-10-27T07:43:56Z
dc.date.available2014-10-27T07:43:56Z
dc.date.issued2009
dc.descriptionMasteren_US
dc.description.abstractAlthough type IV pilus has been implicated in the phototactic motility of some unicellular cyanobacteria, its regulatory mechanism and the effect of environmental factors on motility are still unknown. Equally important is the ability of cyanobacterial cells to anchor themselves to an environment that is conducive for survival. In this study, the motility of a newly isolated unicellular brackish cyanobacterium Synechocystis sp. UNIWG was compared with its morphologically and phylogenetically similar freshwater cyanobacterium Synechocystis sp. PCC6803. The phototactic motility of Synechocystis sp. UNIWG on semisolid BG-11 medium with various concentrations of nitrogen source was significantly faster than that of Synechocystis PCC6803. Interestingly, the cell surface of Synechocystis sp. UNIWG showed the presence of rigid spicules when grown in liquid BG-11, a phenomenon that was absent in Synechocystis PCC6803. Negative staining of Synechocystis sp. UNIWG revealed the presence of two distinct pilus morphotypes, which resembled type IV pili and thin pili of Synechocystis PCC6803. This suggested a similar pattern of phototactic motility in both strains. However, the rigid spicules on Synechocystis sp. UNIWG seem to be more of a hindrance during type IV motility. It was found that the spicules were degraded when the cells moved, such as under prolonged darkness and/or depletion of nitrogen source, indicating that the function of the spicules is to attach the cell to an environment that is conducive for its survival. Thus, Synechocystis sp. UNIWG shows phototaxis regulation that is more complex than Synechocystis PCC6803. In addition, Synechocystis sp. UNIWG exhibited tolerance to salinity ranges between 2-8 g L-1 and other metal ions such as calcium, mangan and magnesium are required for the phototactic response of this strain.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/170
dc.language.isoenen_US
dc.subjectBiological Scienceen_US
dc.subjectPhototacticen_US
dc.subjectBrackishen_US
dc.titlePhototactic motility of Synechocystis Sp. uniwg from brackish environmenten_US
dc.typeThesisen_US
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