<i>Bacillus anthracis</i>
            Multiplication, Persistence, and Genetic Exchange in the Rhizosphere of Grass Plants

Saile, Elke; Koehler, Theresa M.

doi:10.1128/aem.72.5.3168-3174.2006

Cited by 160 publications

(131 citation statements)

References 53 publications

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“…Furthermore, it has been shown that under the right conditions, B. anthracis spores can germinate on and around plant roots and that genetic exchange between strains of Bacillus is possible (110). Because of the spore mode of infection, it is important for spores to persist at their site of deposition and not to get washed too deeply into the soil and thus be inaccessible to grazing ruminants in amounts constituting an infectious dose (111).…”

Section: Functions Of the Exosporium In The Environmentmentioning

confidence: 99%

The Exosporium Layer of Bacterial Spores: a Connection to the Environment and the Infected Host

Stewart

2015

Microbiol Mol Biol Rev

138

155

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SUMMARYMuch of what we know regarding bacterial spore structure and function has been learned from studies of the genetically well-characterized bacteriumBacillus subtilis. Molecular aspects of spore structure, assembly, and function are well defined. However, certain bacteria produce spores with an outer spore layer, the exosporium, which is not present onB. subtilisspores. Our understanding of the composition and biological functions of the exosporium layer is much more limited than that of other aspects of the spore. Because the bacterial spore surface is important for the spore's interactions with the environment, as well as being the site of interaction of the spore with the host's innate immune system in the case of spore-forming bacterial pathogens, the exosporium is worthy of continued investigation. Recent exosporium studies have focused largely on members of theBacillus cereusfamily, principallyBacillus anthracisandBacillus cereus. Our understanding of the composition of the exosporium, the pathway of its assembly, and its role in spore biology is now coming into sharper focus. This review expands on a 2007 review of spore surface layers which provided an excellent conceptual framework of exosporium structure and function (A. O. Henriques and C. P. Moran, Jr., Annu Rev Microbiol61:555–588, 2007,http://dx.doi.org/10.1146/annurev.micro.61.080706.093224). That review began a process of considering outer spore layers as an integrated, multilayered structure rather than simply regarding the outer spore components as independent parts.

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Section: Functions Of the Exosporium In The Environmentmentioning

confidence: 99%

The Exosporium Layer of Bacterial Spores: a Connection to the Environment and the Infected Host

Stewart

2015

Microbiol Mol Biol Rev

138

155

View full text Add to dashboard Cite

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“…Together, these results lead to numerous suppositions behind the timing of anthrax outbreaks in endemic areas, pertaining to whether outbreaks are facilitated by (1) an increase in host exposure, through changes in animal behavior or to the environment, (2) an increase in host susceptibility, as a result of various environmental, social or reproductive stressors or (3) variation in concentrations of B. anthracis in the environment, as a result of a bacterial lifecycle outside the host. There has been growing evidence of the activity of B. anthracis outside of hosts (Saile andKoehler 2006, Schuch andFischetti 2009), however a definitive study has yet to demonstrate that the pathogen can multiply to the concentrations needed for a lethal dose. Clearly, during outbreaks lethal doses of B. anthracis are being contracted from the environment.…”

Section: Introductionmentioning

confidence: 99%

Soil ingestion, nutrition and the seasonality of anthrax in herbivores of Etosha National Park

et al. 2013

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Abstract. Anthrax, caused by the bacterium Bacillus anthracis, is a seasonally occurring infectious disease affecting primarily herbivorous wildlife and livestock. The seasonality of anthrax outbreaks varies among locations, making it difficult to develop a single consistent ecological description of this disease. Over 44 years of mortality surveillance, most anthrax cases in Etosha National Park, Namibia are observed in the wet season, although elephants have an anthrax mortality peak in the dry season. Focusing on three host species (plains zebra, Equus quagga; African elephant, Loxodonta africana; and springbok, Antidorcas marsupialis) occupying the endemic anthrax area of Etosha National Park, Namibia, we tested two commonly posited causes of anthrax seasonality in herbivores: increased pathogen exposure due to greater soil contact, and increased host susceptibility due to seasonal nutritional stress. These hypotheses were assessed using fecal sampling and measurement of the percentage of fecal silicates as an index of soil ingestion and fecal nitrogen, phosphorus and crude fiber as nutritional indices. Nutritional quality for all three species was higher in wet than dry seasons. Comparing among wet seasons, nutritional indices showed either a decline in nutrition with increasing rainfall or no significant pattern. All three species had greater soil ingestion in the wet season than the dry season. Higher soil contact during the anthrax peak suggests that anthrax seasonality may in part be due to heightened exposure to B. anthracis in wet seasons, for zebra and springbok. Elephant anthrax deaths do not correspond with the season of increased soil ingestion or grazing, suggesting that other behavioral mechanisms may overshadow foraging-based risk factors for this species. Nutritional stress is unlikely the primary causative factor in wet season anthrax systems, although nutritional stress sufficient to reduce resistance is difficult to assess non-invasively in wild herbivores. In contrast, increased soil ingestion may be an important predisposing factor for wet season anthrax outbreaks. Ultimately, the amount of soil ingested and its importance in the transmission of soil-borne pathogens will vary based on foraging behaviors, intake rates, grassland structure and on the likelihood that foraging areas intersect with pathogen aggregations in the environment.

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“…In the Kruger National Park (Africa) B. anthracis spores have been isolated from animal bones estimated to be about 200 years old . Saile and Koehler (2006) have demonstrated that spores will germinate and establish stable populations of vegetative cells in the rhizosphere of fescue (Festuca arundinacea) grass in the laboratory in an otherwise sterile environment. In natural circumstances the vegetative cells are fragile and die even in simple environments, such as water or milk ( Turnbull et al, 1989).…”

Section: Ecology Of Anthraxmentioning

confidence: 99%

Anthrax

Fasanella¹

2012

Zoonosis

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Bacillus anthracis Multiplication, Persistence, and Genetic Exchange in the Rhizosphere of Grass Plants

Cited by 160 publications

References 53 publications

The Exosporium Layer of Bacterial Spores: a Connection to the Environment and the Infected Host

The Exosporium Layer of Bacterial Spores: a Connection to the Environment and the Infected Host

Soil ingestion, nutrition and the seasonality of anthrax in herbivores of Etosha National Park

Anthrax

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