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Morphological Studies of Synechocystis sp. UNIWG under Polyhydroxyalkanoate Accumulating Conditions  [2005]

Yew, S. P. Jau, M. H. Yong, K. H. Abed, R. M. M. et al.

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Some cyanobacteria are capable of producing polyhydroxyalkanoate (PHA), among which is the unicellular Synechocystis sp. Here, we report the identification and preliminary characterization of a newly isolated strain of Synechocystis sp. UNIWG that is capable of accumulating unusually high number of PHA granules. This cyanobacterium was isolated from oil-contaminated brackish water sample from Wadi Gaza, Palestine. Surprisingly, Nile Blue A staining of PHA-accumulating cells failed to reveal the accumulated PHA granules. Ultrastructural analysis of Synechocystis sp. UNIWG cells grown under nitrogen limiting conditions revealed the presence of up to 17 electron-transparent granules in the cell cytoplasm. Gas chromatography analysis further revealed that these cells contain up to 14 wt% poly(3-hydroxybutyrate) of the cell dry weight. Ultrastructural analysis also revealed that Synechocystis sp. UNIWG cells from the growth phase were covered with a dense layer of pilus like structures. However, these pilus-like structures were not observed in cells from the PHA-accumulation phase. The possible roles of these pilus-like structures and PHA accumulation for the survival of this cyanobacterium is discussed here.