Synechocystis PCC 6803 ~12: Synechococcus PCC 7942 ~5-7 copies/cell
||Yu J et al., Synechococcus elongatus UTEX 2973, a fast growing cyanobacterial chassis for biosynthesis using light and CO₂. Sci Rep. 2015 Jan 30 5: 8132. doi: 10.1038/srep08132. p.1 bottom linePubMed ID25633131
|| Labarre, J., Chauvat, F. & Thuriaux, P. Insertional mutagenesis by random cloning of antibiotic resistance genes into the genome of the cyanobacterium Synechocystis strain PCC 6803. J Bacteriol 171, 3449–3457 (1989).  Bird, A. J., Turner-Cavet, J. S., Lakey, J. H. & Robinson, N. J. A carboxyl-terminal Cys2/His2-type zinc-finger motif in DNA primase influences DNA content in Synechococcus PCC 7942. J Biol Chem 273, 21246–21252 (1998).PubMed ID2498291, 9694883
||Primary source  abstract: "The facultative heterotrophic cyanobacterium Synechocystis sp. strain PCC 6803 was transformed by HaeII Cmr fragments ligated at random to HaeII DNA fragments of the host genome. A similar transformation was done with an AvaII Kmr marker ligated to AvaII host DNA fragments. Integration of the resistance markers into the host genome led to a high frequency of stable Kmr and Cmr transformants."
||P.1 bottom paragraph: "Efforts focusing on understanding cyanobacterial systems are underway however, one drawback compared to E. coli or yeast is that the growth rates of commonly used cyanobacterial model strains are significantly slower, requiring extended timeframes (weeks to months) to accomplish synthetic biology experiments that can be performed in E. coli or yeast in days. Also, many cyanobacteria contain multiple copies of chromosomes (~12 copies/cell in Synechocystis PCC 6803 [primary source 16] and ~ 5–7 copies/cell in Synechococcus PCC 7942 [primary source 17]). Therefore, eliminating a gene from all copies of the chromosome may take several rounds of segregation."