Abstract
Research for biotechnological applications of cyanobacteria focuses on synthetic pathways and bioreactor design, while little effort is devoted to introduce new, promising organisms in the field. Applications are most often based on recombinant work, and the establishment of transformation can be a risky, time-consuming procedure. In this work we demonstrate the natural transformation of the filamentous cyanobacterium Phormidium lacuna and insertion of a selection marker into the genome by homologous recombination. This is the first example for natural transformation filamentous non-heterocystous cyanobacterium. We found that Phormidium lacuna is polyploid, each cell has about 20–90 chromosomes. Transformed filaments were resistant against up to 14 mg/ml of kanamycin. Formerly, natural transformation in cyanobacteria has been considered a rare and exclusive feature of a few unicellular species. Our finding suggests that natural competence is more distributed among cyanobacteria than previously thought. This is supported by bioinformatic analyses which show that all protein factors for natural transformation are present in the majority of the analyzed cyanobacteria.
Highlights
Biotechnology oriented research with cyanobacteria ranges from the production of low-cost material like bulk chemicals or biofuels [1] to high-value compounds like pharmaceutics [2]
Since the non-heterocystous Phormidium lacuna was cultivated under continuous illumination, we considered an interruption of this open reading frame to have no or minor consequences on growth of the transformants
We found that transformants of Phormidium lacuna HE10JO and HE10DO with the kanamycin (Km) resistance cassette (kanR) cassette were resistant against very high Km concentrations
Summary
Biotechnology oriented research with cyanobacteria ranges from the production of low-cost material like bulk chemicals or biofuels [1] to high-value compounds like pharmaceutics [2]. Protocols for NT are generally simple and straight forward [6], but only few naturally competent cyanobacteria (NCC) are known: diverse Synechococcus [7, 8] and Synechocystis [9, 10] strains, Microcystis aeruginosa PCC 7806 [11] and Thermosynechococcus elongatus BP-1 [12].
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