Bacterial genomes are generally smaller and less variant in size among species when compared with genomes of eukaryotes. Bacterial genomes can range in size anywhere from about 130 kbp[1][2] to over 14 Mbp.[3] A study that included, but was not limited to, 478 bacterial genomes, concluded that as genome size increases, the number of genes increases at a disproportionately slower rate in eukaryotes than in non-eukaryotes. Thus, the proportion of non-coding DNA goes up with genome size more quickly in non-bacteria than in bacteria. This is consistent with the fact that most eukaryotic nuclear DNA is non-gene coding, while the majority of prokaryotic, viral, and organellar genes are coding.[4]
Right now, we have genome sequences from 50 different bacterial phyla and 11 different archaeal phyla. Second-generation sequencing has yielded many draft genomes (close to 90% of bacterial genomes in GenBank are currently not complete); third-generation sequencing might eventually yield a complete genome in a few hours. The genome sequences reveal much diversity in bacteria. Analysis of over 2000 Escherichia coli genomes reveals an E. coli core genome of about 3100 gene families and a total of about 89,000 different gene families.[5] Genome sequences show that parasitic bacteria have 500–1200 genes, free-living bacteria have 1500–7500 genes, and archaea have 1500–2700 genes.[6] A striking discovery by Cole et al. described massive amounts of gene decay when comparing Leprosy bacillus to ancestral bacteria.[7] Studies have since shown that several bacteria have smaller genome sizes than their ancestors did.[8] Over the years, researchers have proposed several theories to explain the general trend of bacterial genome decay and the relatively small size of bacterial genomes. Compelling evidence indicates that the apparent degradation of bacterial genomes is owed to a deletional bias.
^McCutcheon, J. P.; Von Dohlen, C. D. (2011). "An Interdependent Metabolic Patchwork in the Nested Symbiosis of Mealybugs". Current Biology. 21 (16): 1366–1372. doi:10.1016/j.cub.2011.06.051. PMC 3169327. PMID 21835622.
^Van Leuven, JT; Meister, RC; Simon, C; McCutcheon, JP (11 September 2014). "Sympatric speciation in a bacterial endosymbiont results in two genomes with the functionality of one". Cell. 158 (6): 1270–80. doi:10.1016/j.cell.2014.07.047. PMID 25175626.
^Han, K; Li, ZF; Peng, R; Zhu, LP; Zhou, T; Wang, LG; Li, SG; Zhang, XB; Hu, W; Wu, ZH; Qin, N; Li, YZ (2013). "Extraordinary expansion of a Sorangium cellulosum genome from an alkaline milieu". Scientific Reports. 3: 2101. Bibcode:2013NatSR...3E2101H. doi:10.1038/srep02101. PMC 3696898. PMID 23812535.
^Land, Miriam; Hauser, Loren; Jun, Se-Ran; Nookaew, Intawat; Leuze, Michael R.; Ahn, Tae-Hyuk; Karpinets, Tatiana; Lund, Ole; Kora, Guruprased; Wassenaar, Trudy; Poudel, Suresh; Ussery, David W. (2015). "Insights from 20 years of bacterial genome sequencing". Functional & Integrative Genomics. 15 (2): 141–161. doi:10.1007/s10142-015-0433-4. PMC 4361730. PMID 25722247. This article contains quotations from this source, which is available under the Creative Commons Attribution 4.0 International (CC BY 4.0) license.
^
Gregory, T. R. (2005). "Synergy between sequence and size in Large-scale genomics". Nature Reviews Genetics. 6 (9): 699–708. doi:10.1038/nrg1674. PMID 16151375. S2CID 24237594.
^Cole, S. T.; Eiglmeier, K.; Parkhill, J.; James, K. D.; Thomson, N. R.; Wheeler, P. R.; Honoré, N.; Garnier, T.; Churcher, C.; Harris, D.; Mungall, K.; Basham, D.; Brown, D.; Chillingworth, T.; Connor, R.; Davies, R. M.; Devlin, K.; Duthoy, S.; Feltwell, T.; Fraser, A.; Hamlin, N.; Holroyd, S.; Hornsby, T.; Jagels, K.; Lacroix, C.; MacLean, J.; Moule, S.; Murphy, L.; Oliver, K.; Quail, M. A. (2001). "Massive gene decay in the leprosy bacillus". Nature. 409 (6823): 1007–1011. Bibcode:2001Natur.409.1007C. doi:10.1038/35059006. PMID 11234002. S2CID 4307207.
^Ochman, H. (2005). "Genomes on the shrink". Proceedings of the National Academy of Sciences. 102 (34): 11959–11960. Bibcode:2005PNAS..10211959O. doi:10.1073/pnas.0505863102. PMC 1189353. PMID 16105941.
Bacterialgenomes are generally smaller and less variant in size among species when compared with genomes of eukaryotes. Bacterialgenomes can range in...
RNA-genome (Bacteriophage MS2). The next year, Fred Sanger completed the first DNA-genome sequence: Phage Φ-X174, of 5386 base pairs. The first bacterial...
modern bacterial classification emphasises molecular systematics, using genetic techniques such as guanine cytosine ratio determination, genome-genome hybridisation...
DNA transfer are in the plasmid genome rather than in the bacterialgenome, it has been argued that conjugative bacterial gene transfer, as it occurs in...
Institute filed patents for the Mycoplasma laboratorium genome (the "minimal bacterialgenome") in the U.S. and internationally in 2006. The ETC group...
the relationships of prophages from bacterialgenomes. At present there are 24 cyanobacteria for which a total genome sequence is available. 15 of these...
minimum bacterialgenome tend to be substantially more related to proteins found in archaea and eukaryotes compared to the average gene in the bacterial genome...
de Jong PJ (March 2001). "A bacterial artificial chromosome library for sequencing the complete human genome". Genome Research. 11 (3): 483–496. doi:10...
part of the genetic makeup of bacterial strains. For example, an antibiotic target may be absent from the bacterialgenome. Acquired resistance results...
(the result of phage genome acquisition of bacterial host genetic sequences). Evolutionary mechanisms shaping the genomes of bacterial viruses vary between...
bacteriophage nucleic acid into the host bacterium's genome or formation of a circular replicon in the bacterial cytoplasm. In this condition the bacterium continues...
Bacterial cell structure Combrex Evolution of cells Evolution of sexual reproduction List of sequenced archaeal genomes List of sequenced bacterial genomes...
involves the viruses injecting their genome into bacterial cells, inserting those genes into the bacterialgenome, and hijacking the bacteria's machinery...
the bacterial chromosome first. Due to the F factor's inherent tendency to transfer itself during conjugation, the rest of the bacterialgenome is dragged...
to "phage") genome that is integrated into the circular bacterial chromosome or exists as an extrachromosomal plasmid within the bacterial cell. Integration...
Genome editing, or genome engineering, or gene editing, is a type of genetic engineering in which DNA is inserted, deleted, modified or replaced in the...
circuit that promotes bacterial invasion of tumour cells. 2010: Researchers publish in Science the first synthetic bacterialgenome, called M. mycoides...
750-kb bacterial clone contig and restriction map in the region of human chromosome 21 containing the progressive myoclonus epilepsy gene". Genome Research...
methanogens. A large amount of their genome, 126 composite gene families, are derived from genetic material from bacterialgenomes. This has allowed them to adapt...
human genome is still being revised) than A. dubia, however, their genome size far outweighs the genome size of individual bacteria. The first bacterial and...
Another mechanism of genome evolution is provided by transduction whereby bacteriophages introduce new DNA into a bacterialgenome. The main mechanism...
premature stop codons. Pseudogenes are a type of junk DNA. Most non-bacterialgenomes contain many pseudogenes, often as many as functional genes. This...
One species of myxobacteria, Minicystis rosea, has the largest known bacterialgenome with over 16 million nucleotides. The second largest is another myxobacteria...
the reads could be aligned to 194 public human gut bacterialgenomes and 7.6–21.2% to bacterialgenomes available in GenBank which indicates that there is...
Bacterial phyla constitute the major lineages of the domain Bacteria. While the exact definition of a bacterial phylum is debated, a popular definition...
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