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General Session 3: Biological oceanography & global change |
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Exploring the diversity of marine planktonic cyanobacterial assemblages in a coastal biotope- integration of uncultured and cultured approaches
Tuesday 10th @ 1445-1505
Multi-function Hall
Tarkeshwar Singh, Integrative Taxonomy and Microbial Ecology Research Group, Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur – 741246, Nadia, West Bengal, India
Punyasloke Bhadury* , Integrative Taxonomy and Microbial Ecology Research Group, Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur – 741246, Nadia, West Bengal, India
Presenter Email: pbhadury@gmail.com
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| In coastal ecosystems such as mangroves, community composition of marine planktonic cyanobacteria and their resulting importance in primary production is not very well understood. In this study, effect of seasonal precipitation on the structure of marine planktonic cyanobacterial communities were tracked during monsoon and post-monsoon seasons of 2012 in Sundarbans mangrove ecosystem facing the Bay of Bengal using 16S rRNA clone library and sequencing approach along with measurement of in situ environmental parameters. In total 478 clones were sequenced, out of which 222 16S rRNA clones were planktonic cyanobacteria-like and rest were eukaryotic-plastid and bacterial 16S rRNA sequences. It was found that the studied environment was dominated by three major clades of Synechococcus-like 16S rRNA sequences in monsoon and post-monsoon seasons. Two Synechococcus clades were found to dominate the clone libraries when salinity was high while one clade was dominant in low salinity. Besides Synechococcus-like 16S rRNA sequences, Oscillatoriales-like 16S rRNA clade, Stigonematales-like 16S rRNA clade and also a novel cyanobacterial clade represented by uncultured 16S rRNA sequences from the study area were also found based on molecular phylogeny. In total 46 OTUs were encountered, out of which highest number of OTUs (35) were found in monsoon season. Principal component analysis showed that salinity played an important role in influencing the community composition of planktonic cyanobacterial communities in Sundarbans. In Synechococcus-like clades, novel sub-clades were detected thereby highlighting that this ecosystem can harbour novel Synechococcus strains. Moreover, the existence of several novel Synechococcus-like clades in other marine ecosystems globally was also encountered based on deep phylogeny. Most importantly, from the Sundarbans mangrove ecosystem, a new strain of Synechococcus has been successfully established based on cultured approach and characterized using polyphasic taxonomy. Therefore, uncultured and cultured based approaches can ultimately help us towards improved understanding of the contribution of marine planktonic cyanobacteria in primary production, particularly in subtropical and tropical coastal biotopes. |
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