Endospore-forming Bacteria and their Role in Biodefense Essay Example for Free

Endospore-forming Bacteria and their Role in Biodefense Essay Bacteria that have the ability to produce non-reproductive structures or endospores during unfavorable environmental conditions are termed endospore-forming bacteria. Two genera of bacteria in which sporulation are predominant are Bacillus and Clostridium. Bacilli are rod-shaped bacteria, species of which are either obligate or facultative aerobes. The genera include both free-living and pathogenic species. When conditions become unfavorable, the bacterial populations thrive by producing endospores or cysts which can remain dormant and viable for prolonged periods. The genera include several species such as Bacillus anthracis, B. coagulans, B. megaterium, B. cereus, B. globigii, B. natto, B. infernus, B. licheniformis, B. subtilis, thuringiensis, B. polymyxa and B. sphaericus. Of these, the most pathogenic ones are B. anthracis and B. cereus. B. anthracis causes anthrax. B. cereus causes a foodborne illness. B. subtilis and B. coagulans are microbes that cause food spoilage. B. thuringiensis, is an insect pathogen and is therefore a potential biocontrol agent, while B. subtilis is used as model organism in research. Clostridium is a genus of Gram-positive, rod-shaped bacteria, which are obligate anaerobes. They are also capable of producing endospores under stressful or unfavorable environmental conditions. Species include Clostridium acetobutylicum, C. beijerinckii, C. aerotolerans, C. bifermentans, C. chauvoei, C. botulinum, C. butyricum, C. difficile, C. formicaceticum, C. colicanis, C. laramie, C. perfringens, C. ljungdahlii, C. novyi, C. piliforme, C. phytofermentans, C. sordellii, C. scatologenes, C. tetanie, C. tyrobutyricum and C. sporogenes. Five species of this genus are highly pathogenic. These are C. botulinum, C. perfringens, C. tetani, C. sordellii and C. difficile. C. botulinum causes botulism by producing toxin in food or wound. C. perfringens causes varied disease symptoms such as food poisoning, gas gangrene, enterotoxemia in cattle. This species also causes food spoilage. C. tetani causes tetanus. C. sordellii is a microbe associated with deaths of women post childbirth. C. difficile causes pseudo-membranous colitis. Both these genera of gram-positive bacteria are capable of producing endospores in response to nutrient depletion. According to Liu et al (2004), spores are dormant bacterial morphotypes able to endure harsh environments for decades, thus making it easier to be formulated and dispersed as a biological weapon. B. anthracis spores are highly persistent and can simply be â€Å"weaponized† for routing through air, food or water. The formulated spores are usually dry and concentrated, which can reach the human body by inhalation, ingestion, or cutaneous contact and cause anthrax. Infection is severe upon inhalation on endospores of B. anthracis. When inhaled, the spores enter lungs and reach deep into the alveolar spaces. From there they traverse into the medistinal and peribronchial lymph nodes. Once they reach the blood stream, they begin to multiply by switching on to the vegetative cycle and produce toxins that are lethal (Young and Collier, 2002). These are potential biodefense agents because, B. anthracis endospores when dispersed in the air as 1-to-5- µm particles may create a threat over a larger geographical location. In Russia, an accidental release of endospores from a military biologic-weapons facility in Sverdlovsk caused anthrax in humans as far as 4 km from the site, and cases in animals extended as far as 50 km away (Swartz, 2001). The detection of anthrax spores is also not easy and technologically also it is not realistic for rapid in-place detection to be done (Webb, 2003). Nevertheless, when diagnosed immediately the severity can be decreased, administration of oral antibiotic prophylaxis during the incubation stage has proved to be successful. However, once the fulminant stage is attained, the disease is clear of treatment and without doubt lethal (CDC, 2002). According to Inglesby et al. (2002), vaccination is supposedly effectual but the drawback is that a series of six shots over 18 months followed by annual booster shots is a pre-requisite for complete immunity. Therefore, it is obvious that when used as a biological weapon, spores of B.anthracis are capable of inflicting immeasurable torment on man and animals. This elects it to be an ideal candidate for biodefense. References CDC. (2002). Public Health Emergency Preparedness and Response (November, 2002) www. bt. cdc. gov_agent_anthrax_index. asp. Inglesby, T. V. , O’Toole, T. , Henderson, D. A. , Bartlett, J. G. , Ascher, M. S. , Eitzen, E. , Friedlander, A. M. , Gerberding, J. , Hauer, J. , Hughes, J. , et al. (2002). Anthrax as a Biological Weapon, J. Am. Med. Assoc. 287, 2236–2252. Liu, H. , Bergman, N. H. , Thomason, B. , Shallom, S. , Hazen, A. , Crossno, J. , Rasko, D. A. , Ravel, J. , Read, T. D. , Peterson, S. C. , Yates J. and Hanna, P. C. (2004). Formation and Composition of the Bacillus anthracis Endospore. Journal of Bacteriology. 186 (1), 164–178. Swartz, M. N. (2001). Recognition and management of anthrax an update. N Engl J Med. 345, 1621-1626. Webb, G. F. (2003). A silent bomb: The risk of anthrax as a weapon of mass destruction. PNAS. 100(8), 4355–4356 Young, J. A. T. and Collier, R. J. (2002) Attacking Anthrax. Sci. Am. 286, 48–59.