Ultramicrobacteria

• Main Author: Duda, Vitaly I
• Format: Other/Unknown Material
• Language: English
• Published: Wiley 2011
• Subjects: Greenland; Ice; permafrost
• Online Access: http://dx.doi.org/10.1002/9780470015902.a0000309.pub2; https://onlinelibrary.wiley.com/doi/pdf/10.1002/9780470015902.a0000309.pub2; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/9780470015902.a0000309.pub2

Abstract Ultramicrobacteria (UMB) are species of the domain Bacteria, whose cells possess a volume of less than 0.1 μm 3 and a small size of genome (from 3.2 to 0.58 Mb). UMB feature a combination of such determining characters as ultrasmall size of proliferating cells and small size of genome. As a synonym for UMB, some authors use the term ‘nanobacteria’ (NB). Several dozens of UMB species have been isolated from various habitats, such as aquatic and soil environments, sediments, silts, Greenland ice, permafrost, human intestines and insects; and are cultured under laboratory conditions on various nutritive media. The term ‘nan(n)obacteria’ is also used to designate ultrasmall bacterium‐like particles occurring in rocks, sands, soils, in deep subsurface, meteorite and clinical samples. UMB include species of free‐living and parasitic bacteria. They are characterised by a great diversity of morphology, ultrastructural organisation, physiology, biochemistry and ecology. Unique processes UMB perform are dehalorespiration, epibiont obligate and facultative parasitism, synthesis of organic compounds in oceanic waters involving bacteriorhodopsin. UMB have been found among organisms of six large phylogenetic branches of prokaryotes, where their nearest relatives are organisms with larger, typical‐of‐bacteria, cells; this is indicative of the polyphyletic origin of the currently known UMB species by reductive evolution. Key Concepts: Formation of a minimal autoreplicating microbial cell is the prerogative of the prokaryotes. Ultrasmall size of cells enables parasitism (predation) of UMB on ‘large‐cell’ species of prokaryotes. UMB are important model objects for studies of genome evolution in prokaryotes. UMB studies are of vital importance for solving issues of the origin and evolution of primeval living objects. UMB research opens new vistas for biotechnology. Use of UMB representatives, mycoplasms, played a crucial role in epochal works by J Craig Venter and collaborators for experimentally creating a new living ...