Khan, Zoya
(2019)
Genomic And Physiological
Characterisation Of Selected
Arctic, Temperate And Tropical
Pseudanabaena Strains.
PhD thesis, Perpustakaan Hamzah Sendut.
Abstract
Three filamentous cyanobacteria strains obtained from the High Arctic
Svalbard archipelago, temperate (England) and tropical (Malaysia) regions were
characterized using combined phenotypic and genetic approaches. Morphological and
ultrastructural observations were performed together with growth measurements. Cell
dimensions, thylakoid arrangement and apical cell shape of the Arctic and temperate
strains were consistent with the description of Pseudanabaena catenata while the
tropical strain was identified as Pseudanabaena amphigranulata. 16S rRNA gene
analysis showed that the Arctic strain USMAC16 and temperate strain NIVA-CYA146
shared high sequence similarity (100% and 98%, respectively) with P. catenata SAG
1464-1. The tropical strain USMAC18 shared only 94% sequence similarity with
Pseudanabaena sp. PCC 6802, suggesting that the strain is distinctly different from
the strains currently available in the databases. All three strains showed identical
internal transcribed spacer (ITS) configuration with other strains of Pseudanabaena. Cultures of each strain were exposed to various temperature and photoperiod treatments in order to examine phenotypic plasticity. The maximum cell length of Arctic and temperate strains (5.92±0.7 pm and 5.79±0.26 pm, respectively) was observed at 15°C culture temperature, and that of the tropical strain (5.7±0.07 pm) was at 25°C, all under 12L:12D hours (L: light, D: dark) photoperiod.
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