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Francisella Philomiragia Subsp. Noatunensis Subsp. Nov., Isolated From Farmed Atlantic Cod (Gadus Morhua L.), Torstein Tengs
Francisella Philomiragia Subsp. Noatunensis Subsp. Nov., Isolated From Farmed Atlantic Cod (Gadus Morhua L.), Torstein Tengs
Dr. Torstein Tengs
Seven bacterial isolates from farmed Atlantic cod displaying chronic granulomatous disease were characterized by phenotypic and molecular taxonomic methods. The isolates were Gram-negative, facultatively intracellular, non-motile, strictly aerobic coccobacilli which produced H2S from cysteine-supplemented media and are therefore phenotypically consistent with members of the genus Francisella. Comparison of 16S rRNA gene sequences and six partial housekeeping gene sequences (groEL, shdA, rpoB, rpoA, pgm and atpA) confirmed the organism as a member of the genus Francisella, with Francisella philomiragia as its closest relative (99.3% 16S rRNA gene sequence similarity, 92.2–99.0% housekeeping gene sequence similarity). Despite the close relationship with F. philomiragia, …
Phenotypically Different Microalgal Morphospecies With Identical Ribosomal Rna: A Case Of Rapid Adaptive Evolution?, Torstein Tengs
Phenotypically Different Microalgal Morphospecies With Identical Ribosomal Rna: A Case Of Rapid Adaptive Evolution?, Torstein Tengs
Dr. Torstein Tengs
The agents driving the divergence and speciation of freeliving microbial populations are still largely unknown. We investigated the dinoflagellate morphospecies Scrippsiella hangoei and Peridinium aciculiferum, which abound in the Baltic Sea and in northern temperate lakes, respectively. Electron microscopy analyses showed significant interspecific differences in the external cellular morphology, but a similar plate pattern in the characteristic dinoflagellate armor. Experimentally, S. hangoei grew in a wide range of salinities (0–30), whereas P. aciculiferum only grew in low salinities (0–3). Despite these phenotypic differences and the habitat segregation, molecular analyses showed identical ribosomal DNA sequences (ITS1, ITS2, 5.8S, SSU, and partial …