Massive gene decay in the leprosy bacillus

The lactic acid bacterium Streptococcus thermophilus is widely used for the manufacture of yogurt and cheese. This dairy species of major economic importance is phylogenetically close to pathogenic streptococci, raising the possibility that it has a potential for virulence. Here we report the genome sequences of two yogurt strains of S. thermophilus . We found a striking level of gene decay (10% pseudogenes) in both microorganisms. Many genes involved in carbon utilization are nonfunctional, in line with the paucity of carbon sources in milk. Notably, most streptococcal virulence-related genes that are not involved in basic cellular processes are either inactivated or absent in the dairy streptococcus. Adaptation to the constant milk environment appears to have resulted in the stabilization of the genome structure. We conclude that S. thermophilus has evolved mainly through loss-of-function events that remarkably mirror the environment of the dairy niche resulting in a severely diminished pathogenic potential. Supplementary information The online version of this article (doi:10.1038/nbt1034) contains supplementary material, which is available to authorized users.

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“…This is the first instance where regressive evolution is observed in a food niche rather than in pathogen-or symbiont-host situations 22,23 .…”

Section: Discussionmentioning

confidence: 82%

Complete sequence and comparative genome analysis of the dairy bacterium Streptococcus thermophilus

et al. 2004

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“…For example, Y. pestis seems to be at the very early stages of evolution and has both lost and acquired genes during this process 38 . Mycobacterium leprae 39 and Rickettsia prowazekii 40 seem to have evolved solely by gene loss from a progenitor species 39 . The genome sequence of F. tularensis SCHU S4 shows extensive inactivation of genes and a duplicated region that is strongly implicated in virulence and may be a pathogenicity island.…”

Section: Discussionmentioning

confidence: 99%

The complete genome sequence of Francisella tularensis, the causative agent of tularemia

et al. 2005

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Francisella tularensis is one of the most infectious human pathogens known. In the past, both the former Soviet Union and the US had programs to develop weapons containing the bacterium. We report the complete genome sequence of a highly virulent isolate of F. tularensis (1,892,819 bp). The sequence uncovers previously uncharacterized genes encoding type IV pili, a surface polysaccharide and iron-acquisition systems. Several virulence-associated genes were located in a putative pathogenicity island, which was duplicated in the genome. More than 10% of the putative coding sequences contained insertion-deletion or substitution mutations and seemed to be deteriorating. The genome is rich in IS elements, including IS630 Tc-1 mariner family transposons, which are not expected in a prokaryote. We used a computational method for predicting metabolic pathways and found an unexpectedly high proportion of disrupted pathways, explaining the fastidious nutritional requirements of the bacterium. The loss of biosynthetic pathways indicates that F. tularensis is an obligate host-dependent bacterium in its natural life cycle. Our results have implications for our understanding of how highly virulent human pathogens evolve and will expedite strategies to combat them.

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“…The genome is predicted to encode 2 134 coding sequences larger than 30 aa, of which 719 (33.7%) are hypothetical. In contrast to other similar intracellular pathogens, Chlamydia [157], Rickettsia [115], Mycobacterium [33], C. burnetii possesses 29 insertion sequence (IS) elements. There are 21 copies of a unique IS110-related isotype, named IS1111, 5 IS30 and 3 ISAs1 family elements, and 3 degenerate transposase genes of unknown lineage [63].…”

Section: Bacteriologymentioning

confidence: 99%

Is Q Fever an emerging or re-emerging zoonosis?

2005

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-Q fever is a zoonotic disease considered as emerging or re-emerging in many countries. It is caused by Coxiella burnetii, a bacterium developing spore-like forms that are highly resistant to the environment. The most common animal reservoirs are livestock and the main source of infection is by inhalation of contaminated aerosols. Although the culture process for Coxiella is laborious, advances on the knowledge of the life cycle of the bacterium have been made. New tools have been developed to (i) improve the diagnosis of Q fever in humans and animals, and especially animal shedders, (ii) perform epidemiological studies, and (iii) prevent the disease through the use of vaccines. This review summarizes the state of the knowledge on the bacteriology and clinical manifestations of Q fever as well as its diagnosis, epidemiology, treatment and prevention in order to understand what factors are responsible for its emergence or re-emergence. Coxiella burnetii / epidemiology / bacteriology / diagnostic / control

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Massive gene decay in the leprosy bacillus

Cited by 1,597 publications

References 40 publications

Complete sequence and comparative genome analysis of the dairy bacterium Streptococcus thermophilus

Complete sequence and comparative genome analysis of the dairy bacterium Streptococcus thermophilus

The complete genome sequence of Francisella tularensis, the causative agent of tularemia

Is Q Fever an emerging or re-emerging zoonosis?

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