Deinococcus–ThermusGroup

Abstract

The Deinococcus–Thermus group represents an ancient lineage that contains some of the most conspicuous species within the domain Bacteria . The group is distinguished by species that resist the lethal effects of exposure to ionising radiation and ultraviolet light, and by species that thrive at high temperature. Deinococcus–Thermus is comprised of two orders, the Deinococcales and the Thermales . The mostly mesophilic species of Deinococcales demonstrate uncommon resistance following exposure to electromagnetic radiations, tolerating doses that normally destroy vegetative bacteria. The Thermales are thermophilic with optimal growth at temperatures between 60 and 80 °C, but show no evidence of resistance to electromagnetic radiation. Despite these striking and distinctive phenotypic differences, 16S ribosomal ribonucleic acid sequences verify that members of these orders are specifically related to each other. Key Concepts Species within the Deinococcus–Thermus group exist over a wide geographic distribution within the natural and built environments. All species within the Deinococcus–Thermus group are specifically related to each other through their 16S rRNA sequences. Members of the Deinococcales and Thermales share only three phenotypic characteristics: all are nonmotile, none form endospores and all utilise menaquinone 8 as their major respiratory lipoquinone. Members of the Deinococcales are aerobic, chemoorganotrophic and display respiratory metabolism. Other chemotaxonomic characteristics of this order are more varied than might be expected for closely related species. Most members of the Deinococcales display extreme resistance to the lethal effects of ionising radiation and UV light; there is a subset of species that are substantially less resistant to these agents. Members of the Thermales are thermophilic or slightly thermophilic rods. Optimal growth temperature for the type strains within the order falls between 60 and 70 °C, but there is considerable variation in growth temperature among nontype species. Most members of the Thermales are aerobic chemoorganotrophs reported to grow between pH 5.0 and 10.5 with optimal growth between pH 6 and 7. In the presence of an appropriate electron acceptor, some species will grow anaerobically. Members of the Thermales are routinely isolated from hydrothermal features worldwide at freshwater and marine sites, including deep sea hydrothermal vents.

The influence of electrokinetic bioremediation on subsurface microbial communities at a perchloroethylene contaminated site

“…7 4 % ) , s u l f a t e -r e d u c i n g Syntrophobacterales (4.33%), Spirochaetales (2.25%) and MBNT15 (10.86%) commonly found in sediments, as well as to the dechlorinating Chloroflexi Dehalococcoides (12.16%) (He et al 2005;Plugge et al 2011;Handley et al 2015;Huang et al 2017). Other dominant phylotypes included the aerobic, chemoorganotrophic Deinococcales (19.95%), Burkholderiales (6.53%) commonly found in soil systems, and the phylum OD1 (18.45%), previously identified in anoxic groundwater environments (Willems et al 1991;Nelson and Stegen 2015;Battista 2016). Samples taken after the second incubation phase showed similar spatial variation in microbial community structure.…”