Transformation of Cyanobacteria

Abstract

Cyanobacteria are a diverse and successful group of bacteria defined by their ability to carry out oxygenic photosynthesis. They occupy diverse ecological niches and are important primary producers in the oceans. Cyanobacteria are amenable to genetic manipulation. Some strains are naturally transformable. Many others have been transformed in the lab by conjugation or electroporation. The ability to transform cyanobacteria has been determinant in the development of the molecular biology of these organisms and has been the basis of many of their biotechnological applications. Cyanobacteria are the source of natural products and toxins of potential use and can be engineered to synthesize substances of biotechnological interest. Their high protein and vitamin content makes them useful as a dietary supplement. Because of their ability to occupy diverse ecological niches, they can be used to deliver to the medium substances of interest or as biosensors.

Biodesalination: A Case Study for Applications of Photosynthetic Bacteria in Water Treatment

“…Several detailed reviews have been published on the genetic manipulation of cyanobacteria in general (Koksharova and Wolk, 2002;Vioque, 2007;Heidorn et al, 2011;Wilde and Dienst, 2011). Here we will only give a short overview with emphasis on available tools for Synechococcus sp.…”

“…As mentioned above, the process of natural transformation involves DNA linearization and conversion to a single strand (Porter, 1986), which makes this technique unsuitable for genes on an autonomously replicating plasmid. In this case, conjugation is the method of choice because it ensures that a circular plasmid resides in the host at the end of the transfer (Vioque, 2007). Integration into the host genome by natural transformation is desirable when long-term inheritance is the goal.…”

“…Mixing of the two E. coli strains causes the conjugative plasmid to transfer to the E. coli strain that carries the cargo and helper plasmids. The latter is then competent to conjugate with the subsequently added cyanobacterial strain and to transfer the cargo plasmid to the new host (Vioque, 2007;Wilde and Dienst, 2011).…”

“…However, target sites differ between cyanobacterial species, which is one reason why a shuttle or broad host vector that is maintained in one species might be digested in another. A second approach is used in conjugation, in which the helper plasmid can encode methylases that protect against restriction enzymes commonly present in many cyanobacteria (Vioque, 2007).…”

Genetic engineering of cyanobacteria as biodiesel feedstock.

“…On the other hand, cyanobacteria are very amenable to genetic engineering. Many species of cyanobacteria are naturally transformable, meaning they will naturally uptake exogenous DNA [14]. Like other prokaryotes, cyanobacteria use homologous recombination to integrate DNA into targeted regions of the genome, and their gene expression has not been shown to be regulated by complex mechanisms such as RNAi.…”