Synechococcus elongatus
When someone hears the word bacterium, they might assume that the species in question is likely to cause diseases. However, Synechococcus elongatus is not known to cause any diseases. What makes this bacterium particularly interesting is its ability to grow very rapidly. (Schubert, 2020) reports that these bacteria double their body size sixteen times a day, which translates to a daily growth of sixteen million percent. These bacteria have several real-world aspects that could help improve humanity considerably. Synechococcus elongatus could be used to produce food quickly while avoiding fertilizers that usually cause climate change (Schubert, 2020). Since the bacterium uses carbon dioxide to build their bodies, it also could be used as carbon sinkers to help clean up greenhouse gases. It might even be developed to make paper, saving the trees (Schubert, 2020). In theory, this bacteria could also be released to the world’s oceans to allow for carbon fixation, but that might not be possible without further research (Schubert, 2020). All the same, aspects like these require further investigation to determine whether they are viable or even possible at that.
Synechococcus elongatus is rod-shaped and unicellular and usually exists in its habitat single, linearly connected, paired, or in small clusters (Microbewiki, 2011). The bacterium does have locomotory organelles, such as cilia or flagella, but it moves all the same (Sokol & Olszewski, 2014). In addition to this, the bacterium has an envelope structure where the contents of the outer membrane are arranged in a rhomboid lattice, with the membrane being enclosed by a crystalline surface (Samuel, Petersen, & Reese, 2001). The outer membrane also has spicules that extend about 150 nanometers into the surrounding fluid, and inwards to the inner membrane which allows movement by ion-motive force (Sokol & Olszewski, 2014). The spicules are the structures that these bacteria use for movement. All the same, movement is not influenced by the light because this species is able to use the sun, carbon dioxide, and water to use for photosynthesis (Microbewiki, 2011). These two membranes envelop the cell on the inside(Sokol & Olszewski, 2014). Notably, the cell’s genome structure includes one circular chromosome and two plasmids (Microbewiki, 2011).
Typical cells usually have a beta-clamp, otherwise known as a sliding clamp, that encircles the DNA, binds to the DNA polymerase, and tethers it to the DNA template (Altieri & Kelman, 2018). The main purpose of this sliding clamp is to facilitate processive replication (Altieri & Kelman, 2018). However, beta-clamps are not only limited to their function in replication. They also play a significant role in DNA repair, cell cycle progression and control, and cell recombination. Replication is usually a complex process and so it requires a number of additional factors. In addition to the beta-clamp, organisms usually have single-stranded binding protein, which allows for DNA replication by providing the energy needed to separate two parent DNA strands and the energy needed to keep these two strands apart from each other (Ashton et al., 2013). These two factors are complementary because the single-stranded binding proteins cause the DNA to separate, while the beta-clamp can do the same, but it also allows the cells to recombine.
There are two different time periods during replication, elongation time (C period) and division time (D period). The C period is the amount of time that it takes to replicate the bacterial chromosome, which is close to 40 minutes ( Ming Chu & Hardison, 2020). The D period is the amount of time that goes by between the completion of a round of DNA and completion of cell division, which is close to 20 minutes. The replication cycle for bacteria with doubling times is typically about 60 minutes. However, a cell’s doubling time could be less than 60 minutes. In that case, a cycle of replication must initiate before the end of the ongoing cycle ( Ming Chu & Hardison, 2020). Multiple replication forks allow bacteria to divide faster than the initial replication cycle time. ( Ming Chu & Hardison, 2020). According to Langston, O’Donnell, & Stillman, “In bacteria, the DNA replication machinery is assembled at the single origin of DNA replication in a characteristic location (Langston, O’Donnell, & Stillman, 2013).” When the initiation of DNA replication is complete, new origins come out of the replisome and the origins go to their locations. The origins of DNA replication are connected to DNA components that move the DNA and prepare the cell for the daughter chromosomes separation before cell division (Langston, O’Donnell, & Stillman, 2013). Depending on how fast the bacteria grows, there is a possibility that re-initiation of DNA replication from the origin can occur. All in all, DNA replication is included in bacterial cell division (Langston, O’Donnell, & Stillman, 2013). The circadian clock has a huge impact on DNA replication. Cyanobacteria uses the circadian clock to make sure DNA replication completes (Liao & Rust, 2021). Cyanobacteria starts its DNA replication in the morning until around nightfall. (Liao & Rust, 2021) suggests that the clock shapes the metabolic state of the cell at a specific time to undergo DNA polymerization in the dark, which allows for replication to complete (Liao & Rust, 2021). If cells enter the dark at the incorrect time, then it would be unable to complete DNA replication (Liao & Rust, 2021). Typically, cells reach maximum levels of replication during nightfall. Cells have a minimum level of replication at dawn (Liao & Rust, 2021).
In conclusion, Cyanobacteria, such as Synechococcus elongatus, grows rapidly and goes through many different cellular processes. Cell division and DNA replications are processes that the bacteria undergoes. Cyanobacteria could also be used for many things such as making paper.
Reference list
Altieri, A.S. and Kelman, Z. (2018). DNA Sliding Clamps as Therapeutic Targets. Frontiers in Molecular Biosciences, 5.
Ashton, N.W., Bolderson, E., Cubeddu, L., O’Byrne, K.J. and Richard, D.J. (2013). Human single-stranded DNA binding proteins are essential for maintaining genomic stability. BMC Molecular Biology, 14(9), p.
Liao, Y. & Rust, M.J., 2021. The circadian clock ensures successful DNA replication in cyanobacteria. PNAS. Available at: https://www.pnas.org/content/118/20/e2022516118 [Accessed June 27, 2021].
Microbewiki (2011). Synechococcus elongatus. [online] Microbewiki. Available at: https://microbewiki.kenyon.edu/index.php/Synechococcus_elongatus#References [Accessed 22 Jun. 2021].
Ming Chu, T. & Hardison, R., 2020. Replication in Bacteria. Biology LibreTexts. Available at: https://bio.libretexts.org/Bookshelves/Genetics/Book%3A_Working_with_Molecular_Genetics_(Hardison)/Unit_II%3A_Replication_Maintenance_and_Alteration_of_the_Genetic_Material/6._DNA_replication_II%3A_Start%2C_stop_and_control/Replication_in_Bacteria [Accessed June 27, 2021].
O’Donnell, M., Langston, L. & Stillman, B., 2013. Principles and concepts of DNA replication in bacteria, archaea, and eukarya. Cold Spring Harbor perspectives in biology. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3685895/ [Accessed June 27, 2021].
Samuel, A.D., Petersen, J.D. and Reese, T.S. (2001). Envelope structure of Synechococcus sp. WH8113, a nonflagellated swimming cyanobacterium. BMC Microbiology, [online] 1(4), p.4. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC31413/ [Accessed 27 Jan. 2021].
Schubert, M. (2020). Max Schubert on Fast-Growing Cyanobacteria. [online] Wyss Institute. Available at: https://wyss.harvard.edu/news/max-schubert-on-fast-growing-cyanobacteria/ [Accessed 22 Jun. 2021].
Sokol, K.A. and Olszewski, N.E. (2014). The Putative Eukaryote-LikeO-GlcNAc Transferase of the Cyanobacterium Synechococcus elongatus PCC 7942 Hydrolyzes UDP-GlcNAc and Is Involved in Multiple Cellular Processes. Journal of Bacteriology, 197(2), pp.354–361.