Abstract
Twenty-five marine cyanobacteria isolated from Irish coasts were characterized based on their morphological characters and 16S rRNA gene sequence analysis. In addition, superoxide dismutase (SOD) and malate dehydrogenase (MDH) isoenzyme banding patterns were used to differentiate two morphologically ambiguous isolates. In this study, six new cyanobacteria-specific primers were designed, and a 16S rRNA gene of twenty-five morphologically diverse cyanobacteria was successfully PCR amplified (1198–1396 bps). Assembled 16S rRNA sequences were used both for a basic local alignment search tool (BLAST) analysis for genus-level identification and to generate a phylogenetic tree, which yielded two major clusters: One with morphologically homogenous cyanobacteria and the other with morphologically very diverse cyanobacteria. Kamptonema okenii and Tychonema decoloratum were isolated from a single field sample of Ballybunion and were originally identified as the same ‘Oscillatoria sp.’ based on preliminary morphological observations. However, an alignment of 16S rRNA gene sequences and SOD and MDH isoenzyme banding pattern analyses helped in differentiating the morphologically-indistinguishable ‘Oscillatoria sp.’. Finally, after a re-evaluation of their morphological characters using modern taxonomic publications, the originally identified ‘Oscillatoria sp.’ were re-identified as Kamptonema okenii and Tychonema decoloratum, thus supporting the polyphasic approach of cyanobacteria characterization.
Highlights
Cyanobacteria (AKA blue-green algae) are prokaryotic, oxygen evolving, photosynthetic, Gram-negative bacteria found in a wide variety of habitats including the Arctic, the Antarctic and hot springs
We initiated the identification of twenty-five marine cyanobacteria based on morphological characterization and further molecular characterization based on 16S rRNA gene sequencing, basic local alignment search tool (BLAST) analysis, and phylogenetic analysis
Based on the micro-morphological characters observed under a light microscope, we identified a total of 19 species of 11 genera Anabaena, Calothrix, Chlorogloea, Hyella, Kamptonema, Leptolyngbya, Phormidium, Pseudanabaena, Schizothrix, Spirulina and Tychonema, representing 25 cyanobacterial isolates of the present study
Summary
Cyanobacteria (AKA blue-green algae) are prokaryotic, oxygen evolving, photosynthetic, Gram-negative bacteria found in a wide variety of habitats including the Arctic, the Antarctic and hot springs. Schenk et al [28] studied the malate dehydrogenase (MDH) isoenzyme profile in eight cyanobacterial species with polyacrylamide disc gel electrophoresis and obtained a maximum of eight and a minimum of five bands with different relative mobilities (Rm ) They concluded that the malate dehydrogenase zymograms of cyanobacteria can be used as “fingerprints” and have been used successfully in some cases such as in Anabaena and Nostoc with shared bands; they were not so successful in determining the position of Anacystis nidulans within the order Chroococcales. In this manuscript, we initiated the identification of twenty-five marine cyanobacteria based on morphological characterization and further molecular characterization based on 16S rRNA gene sequencing, basic local alignment search tool (BLAST) analysis, and phylogenetic analysis. We used superoxide dismutase (SOD) and malate dehydrogenase (MDH) isoenzyme banding patterns to resolve the ambiguity between two isolates using a polyphasic approach
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