Center for Insect Science, Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA.
Curr Opin Microbiol. 2010 Feb;13(1):73-8. doi: 10.1016/j.mib.2009.12.002. Epub 2010 Jan 8.
Bacterial genomes vary in size over two orders of magnitude. The Mycoplasma genitalium genome has historically defined the extreme small end of this spectrum, and has therefore heavily informed theoretical and experimental work aimed at determining the minimal gene content necessary to support cellular life. Recent genomic data from insect symbionts have revealed bacterial genomes that are incredibly small-two to four times smaller than M. genitalium-and these tiny genomes have raised questions about the limits of genome reduction and have blurred the once-clear distinction between autonomous cellular life and highly integrated organelle. New data from various systems with symbiotic bacterial or archaeal partners have begun to shed light on how these bacteria may function with such small gene sets, but major mechanistic questions remain.
细菌基因组的大小差异在两个数量级以上。历史上，生殖道支原体基因组定义了这个范围的极端小端，因此它为旨在确定支持细胞生命所需的最小基因含量的理论和实验工作提供了重要信息。最近来自昆虫共生体的基因组数据揭示了细菌基因组小得令人难以置信——比生殖道支原体小两到四倍——这些微小的基因组提出了关于基因组减少极限的问题，并模糊了曾经清晰区分的自主细胞生命和高度整合的细胞器之间的界限。来自具有共生细菌或古菌伙伴的各种系统的新数据开始阐明这些细菌如何在如此小的基因集下发挥作用，但主要的机制问题仍然存在。
