logging in or signing up Bacillus drnaseelsalim Download Post to : URL : Related Presentations : Let's Connect Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Copy embed code: Embed: Flash iPad Dynamic Copy Does not support media & animations Automatically changes to Flash or non-Flash embed WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 553 Category: Education License: All Rights Reserved Like it (0) Dislike it (0) Added: January 21, 2013 This Presentation is Public Favorites: 0 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Bacillus: Bacillus DR SMINA 1/21/2013 1PowerPoint Presentation: Scientific classification Domain: Bacteria Division: Firmicutes Class: Bacilli Order: Bacillales Family: Bacillacea Genus :Bacillus 1/21/2013 2PowerPoint Presentation: Numerous, including: B. alcalophilus B. alvei B. aminovorans B. amyloliquefaciens B. aneurinolyticus B. anthracis B. aquaemaris B. brevis 3PowerPoint Presentation: B. caldolyticus B. centrosporus B. cereus B. circulans B. coagulans B. firmus B. flavothermus B. fusiform 1/21/2013 4PowerPoint Presentation: B. globigii B. infernus B. larvae B. laterosporus B. lentus B. licheniformis B. megaterium B. mesentericus 1/21/2013 5PowerPoint Presentation: B. mucilaginosus B. mycoides B. natto B. pantothenticus B. polymyxa B. pseudoanthracis B. pumilus 1/21/2013 6PowerPoint Presentation: B. schlegelii B. sphaericus B. sporothermodurans B. stearothermophilus B. subtilis B. thermoglucosidasius B. thuringiensis B. vulgatis B. weihenstephanensis 1/21/2013 7PowerPoint Presentation: Sporogenous , rod shaped aerobic bacteria Form heat resistant spores Gram positive-get decolourised easily Motile- peritrichous flagella 1/21/2013 8Definition: Definition The production of resistant endospores in the presence of oxygen remains the defining feature for Bacillus 1/21/2013 9PowerPoint Presentation: The definition was undermined by the discoveries of Bacillus infernus and B. arseniciselenatis strictly anaerobic Spores not observed in B. halodenitrificans , B. infernus , B. selenitireducens , B. subterraneus , and B. thermoamylovorans . 1/21/2013 10Taxonomy: Taxonomy Bacillus divided better-defined groups on the basis of 16S rRNA gene sequencing studies So far, ten new genera have been proposed 1/21/2013 11PowerPoint Presentation: Alicyclobacillus six species of thermoacidophiles Paenibacillus 49 species Brevibacillus 12 species Virgibacillus Gracilibacillus 1/21/2013 12PowerPoint Presentation: Salibacillus two species of halophiles Geobacillus ten species of thermophiles including Bacillus stearothermophilus Ureibacillus with two round- spored , thermophilic species Single - membered Marinibacillus Salibacillus has subsequently been merged with Virgibacilius 1/21/2013 13PowerPoint Presentation: Bacillus continues to accommodate the best-known species such as B. subtilis , B. anthracis B. cereus , B. licheniformis , B. megaterium , B. pumilus , B. sphaericus , and B. thuringiensis . It still remains a large genus, with over 90 species. 1/21/2013 14Habitats: Habitats Most aerobic endospore -formers saprophytes in the natural environment Some species are opportunistic or obligate pathogens animals humans other mammals, and insects 1/21/2013 15PowerPoint Presentation: Habitats Soils of all kinds, ranging from acid to alkaline, hot to cold, and fertile to desert Water columns and bottom deposits of fresh and marine waters. 1/21/2013 16Importance of the aerobic endospore-formers: Importance of the aerobic endospore -formers Most species of aerobic endospore -forming bacteria have little or no pathogenic potential rarely associated with disease in humans and other animals. 1/21/2013 17PowerPoint Presentation: The main exceptions are B. anthracis (anthrax) B. cereus food poisoning and opportunistic infections B. thuringiensis , P. larvae and its subspecies, P. lentimorbus and P. popilliae (all pathogenic to invertebrates) 1/21/2013 18PowerPoint Presentation: spores resistant to Radiation Heat Disinfectants, and desiccation Bacillus species troublesome contaminants in the -operating room On surgical dressings In pharmaceutical products, and in foods. 1/21/2013 19PowerPoint Presentation: several aerobic endosporeformers are of clinical or health importance in very positive ways In the production of antibiotics Bacitracin from B. licheniformis or B. subtilis Gramicidin from Brevibacillus brevis Polymyxin from Paenibacillus polymyxa 1/21/2013 20Vitamins : Vitamins Vitamins B 12 and B 2 from B. megaterium , Biotin and riboflavin from B. subtilis 1/21/2013 21PowerPoint Presentation: As the bases of antibiotic assays B. cereus , B. circulans , B. megaterium , B. pumilis , B. subtilis , and G.stearothermophilus 1/21/2013 22PowerPoint Presentation: In the validation of disinfectants ( B. cereus ) Monitoring of fumigation ( B. subtilis ) Heat sterilization ( G. stearothermophilus ) Radiation ( B. pumilus ) 1/21/2013 23In various clinical tests: In various clinical tests Uric acid assay using B. fastidiosus Chlamydia detection assay - B. subtilis Blood screening test for phenylketonuria utilizing B. subtilis Bacillus species are the active ingredients of probiotics for animals and humans 1/21/2013 24PowerPoint Presentation: Bacillus species commercial importance in the production of industrial enzymes The largest consumer is the detergent industry, one third of the global market in such products Proteases and amylases it uses are all of Bacillus origin 1/21/2013 25PowerPoint Presentation: Bacillus thuringiensis - biopesticide The genes for the δ- endotoxins of B thuringiensis - development of transgenic crop plants Strains of several species show promise as agents to control fungal diseases of plants 1/21/2013 26Peanut leaves-Bt toxin: Peanut leaves-Bt toxin 1/21/2013 27PowerPoint Presentation: Spore formers -important deleterious agents and contaminants in the food industry B. coagulans , B.licheniformis , B. subtilis , G. stearothermophilus , and P.macerans - spoilage of evaporated milk, in which fermentation occurs without gas production 1/21/2013 28PowerPoint Presentation: P. macerans and P. polymyxa – produce both acid and gas- canned food swells and cheese defects. B. cereus causes problems in the dairy industry – it is a regular contaminant of milk, and it causes ‘bitty cream defect ’and ‘sweet curdling ’. B. subtilis causes ‘rope ’in bread, which appears as slimy stringiness when the loaf is cut 1/21/2013 29The endospore: The endospore It was independently discovered by Cohn -1876, Koch -1876 and Tyndall The ability to form endospores in aerobic conditions a defining character of the genus Bacillus since the 1920s 1/21/2013 30PowerPoint Presentation: Endospores are so named - formed intracellularly Optically refractile Highly resistant to chemical and physical stresses that are lethal to vegetative cells 1/21/2013 31PowerPoint Presentation: It is the spores of Bacillus subtilis most intensively studied Especially those of strain 168 The first Bacillus strain to have its genome sequenced 1/21/2013 32PowerPoint Presentation: Endospores formed at the end of exponential growth phase Spores will not be formed under all cultural conditions Cultures may die if conditions are not conducive to sporulation 1/21/2013 33PowerPoint Presentation: One trigger for sporulation is nutritional deprivation Sporulation may be initiated by transferring an actively growing culture from a rich to a poor growth medium 1/21/2013 34PowerPoint Presentation: Man environmental factors affect endospore formation These include Growth temperature Environmental pH Aeration Presence of certain minerals, carbon, nitrogen and phosphorus sources and their concentrations 1/21/2013 35PowerPoint Presentation: Second influence is population density Sporulation is poor at low cell densities, even though the cells may be starved 1/21/2013 36PowerPoint Presentation: Mass of a culture increases Extracellular accumulation of a secreted peptide (competence and sporulation factor (CSF)) Acts as an auto-inducer for quorum sensing High intracellular levels of CSF Increase of the phosphorylated form of a response regulator ( SpoOA ) Leads to derepression of various stationary phase genes, some of which are needed for sporulation 1/21/2013 37Bacillus anthracis: Bacillus anthracis 1. first pathogenic bacterium to be seen under microscope-Pollender,1849 2.first communicable disease to be transmitted by inoculation of infected blood-Davaine,1850 3.first bacterium to be isolated in pure culture and shown to possess spores-Kosh,1876 4. first bacterium used for preparation of attenuated vaccine(Pasteur,1881) 1/21/2013 38BACILLUS ANTHRACIS: BACILLUS ANTHRACIS morphology large (4-8 × 1-1.5 μm ) non-motile, sporing bacillus. spores form readily - artificial media,or soil oval, refractile and central in position. The temperature range for growth is 12-45°C (optimum 35°C); 1/21/2013 39PowerPoint Presentation: In tissues –singly, pairs or in short chains Entire chain surrounded by a capsule Capsule –polypeptide in nature-polymer d- glutamic acid Capsule formed- bicarbonate added or incubated with10-25 % co 2 serum, albumin, charcoal , starch 1/21/2013 40PowerPoint Presentation: Blood films containing anthrax bacilli stained with polychrome methylene blue amorphous purplish material seen around –capsular material- M , Fadyeans reaction 1/21/2013 41PowerPoint Presentation: In cultures, bacilli arranged end to end in long chains 1/21/2013 42PowerPoint Presentation: Ends of bacilli –truncated or concave and swollen- bamboo stick appearance 1/21/2013 43PowerPoint Presentation: Sporulation occurs under unfavourable conditions Distilled water,2% Nacl , oxalated agar Inhibited by calcium chloride 1/21/2013 44PowerPoint Presentation: Spores do not stain by ordinary methods-need special differential stains Sudan black stain-fat globules seen inside bacilli 1/21/2013 45Cultural charecteristics: Cultural charecteristics Aerobe and facultative anaerobe Optimum temp-35-37 0 C Optimum temp –sporulation25-30 0 C Growth occurs on ordinary media 1/21/2013 46PowerPoint Presentation: on agar plates-irregularly round colonies 2-3 mm diameter, raised dull opaque greyish white frosted glass appearance 1/21/2013 47PowerPoint Presentation: Blood agar media-non haemolytic colonies 1/21/2013 48PowerPoint Presentation: Under low power- edge of colony –long interlacing chains of bacilli-resembling locks of matted hair -Medusa head appearance 1/21/2013 49PowerPoint Presentation: Virulent capsulated strains form rough cultures Avirulent strains form smooth colonies 1/21/2013 50PowerPoint Presentation: On gelatin stab culture -inverted fir tree appearance with slow liquefaction commencing from the top 1/21/2013 51PowerPoint Presentation: In broth occurs as floccular deposit with no turbidity When bacillus anthraxis grown on solid medium containing 0.05-.50 u of penicillin/ ml,in 3-6 hrs cells become large spherical and occur in chains – string of pearls reaction 1/21/2013 52PowerPoint Presentation: A selective medium –PLET – Polymyxin,lysozyme,EDTA , Thallous acetate added heart infusion agar-isolate bacillus anthracis from mixtures of othrer spore bearing bacilli 1/21/2013 53Biochemical reactions: Biochemical reactions Glucose,maltose,sucrose are fermented producing acid, no gas Nitrate reduced to nitrite Catalase is formed 1/21/2013 54resistance: resistance Bacilli killed at 60 0 C in 30 mts In dead animals, bacilli remain viable in bone marrow for 1 wk,skin for 2 wks. Spores highly resistant 4% KMno 4 kills in 15 mts 1/21/2013 55duckering: duckering Destruction of spores in animal products when imported in to non endemic countries Formaldehyde 2%, 30-40 0 C,20 mts wool 0.25%, 60 0 C , 6 hrs hairs, bristles 1/21/2013 56PowerPoint Presentation: The pathogenicity of B. anthracis depends primarily on two major virulence factors the poly- d - glutamic acid capsule the toxin complex comprising three proteins - the protective antigen , oedema factor and lethal factor . 1/21/2013 57PowerPoint Presentation: The capsule enhance the virulence of B. anthracis by inhibiting the phagocytosis of vegetative cells in the extracellular environment of the lymphatic system and bloodstream. loss of plasmid, p x 02, which control capsule production leads to loss of virulence 1/21/2013 58PowerPoint Presentation: It is mainly the action of the toxin that mediates damage to the host. The three components of the tripartite toxin combine to form two binary toxins, the oedema toxin and lethal toxin, formed by association of the protective antigen with the oedema factor and lethal factor, respectively. 1/21/2013 59PowerPoint Presentation: 1/21/2013 60PowerPoint Presentation: the protective antigen binds to host cells facilitates the entry of the associated oedema or lethal factor 1/21/2013 61PowerPoint Presentation: The oedema toxin -localized swelling associated with cutaneous anthrax. Oedema factor : calmodulin -dependent adenylate cyclase catalyses the production of intracellular cAMPfrom host aATP Inducing IL-6 and inhibiting TNF-α in monocytes Oedema toxin also increase host susceptibility to infection by impairing neutrophil function. 1/21/2013 62Lethal toxin: Lethal toxin Lethal factor :zinc metalloprotease inactivates mitogen -activated protein kinase , particularly in macrophages. The lethal toxin stimulates macrophages to produce IL-1β and TNF-α. IL-1β accumulates within macrophages and TNF-α is released. concentration of lethal toxin increases, macrophage lysis sudden release of IL-1β shock and death. 1/21/2013 63PowerPoint Presentation: Loss of plasmid p x 0 1 which encodes LF toxin renders the strain avirulent The avirulent Sterne vaccine strain is devoid of plasmid coding for capsular polysaccharide 1/21/2013 64pathogenesis: pathogenesis Anthrax - zoonosis - a disease of animals transmissible secondarily to man. Human beings relatively resistant to infection 1/21/2013 65PowerPoint Presentation: usually a consequence of the exposure of a susceptible host to spores of the bacillus. arises by inoculation through the skin of material from infected animals or their products. Spores are not found in host tissues, but appear on exposure of the vegetative cells to oxygen in the air. 1/21/2013 66PowerPoint Presentation: Local gelatinous hemorrhagic edema at site of inoculation Extensive subcutaneous congestion Enlarged dark red friable spleen Dark blood ,coagulates less firmly 1/21/2013 67Anthrax: Anthrax Animals infected by ingestion of spores present in soil Direct spread from animal to animal is rare Infected animals shed in the dischrages from the mouth, nose and rectum large numbers of bacilli sporulate in soil and remain the source of infection 1/21/2013 68PowerPoint Presentation: spores body by abrasion, inhalation or ingestion phagocytosed by macrophages transported from the site of infection regional lymph nodes the spores germinate and vegetative bacteria multiply. bacilli bloodstream causing massive septicaemia, with up to 10 8 colony-forming units/ml of blood. 1/21/2013 69PowerPoint Presentation: 1/21/2013 70PowerPoint Presentation: The disease may be Cutaneous Pulmonary Intestinal All types can lead to fatal septicemia or meningitis 1/21/2013 71Cutaneous anthrax: Cutaneous anthrax The face , neck ,hands arms and back -usual sites The primary lesion malignant pustule. . Coagulation necrosis of the centre of the pustule results in the formation of a dark-coloured eschar 1/21/2013 72PowerPoint Presentation: surrounded by a ring of vesicles containing serous fluid and an area of oedema and induration severe toxic signs and widespread oedema prognosis is poor. 1/21/2013 73PowerPoint Presentation: 1/21/2013 74Hide porters disease : Hide porters disease The disease used to be common in dock workers carrying loads of hides and skin on their bare backs 1/21/2013 75Inhalational anthrax : Inhalational anthrax consequence of the inhalation of spores acute form of disease high mortality rate. 1/21/2013 76 The infectious human dose by the air-borne route range 25000 to 55000 spores sometimes incorrectly referred to as pneumonic anthrax, the disease does not develop as a bronchopneumoniaPowerPoint Presentation: 1/21/2013 77 multiplication of organisms in bronchi spread lungs, lymphatics and bloodstreamInhalational anthrax: Inhalational anthrax Intense inflammation, haemorrhage and septicaemia Toxins and the considerable bacterial load Increased vascular permeability and hypotension similar to endotoxic shock. 1/21/2013 78Wool sorter , s disease: Wool sorter , s disease cases of inhalational anthrax persons working in industries handling animal skins, hides and wool 1/21/2013 79PowerPoint Presentation: accident at Soviet Union biological weapons factory in the 1980s release of spores into the air. In the town of Sverdlosk 79 cases of human inhalation recorded - 6 weeks after exposure 68 deaths. 1/21/2013 80Intestinal anthrax: Intestinal anthrax Occurs among pastoralists eat dead infected animals. 1/21/2013 81PowerPoint Presentation: after a day or so from haemorrhagic diarrhoea, and dies rapidly from septicaemia. occur as small outbreaks in a family or village. some may suffer only cutaneous lesions cause of the outbreak is easily made clinically 1/21/2013 82PowerPoint Presentation: 1/21/2013 83Naturally occurring infections of animals: Naturally occurring infections of animals All animals are susceptible to anthrax Carnivores relatively resistant Herbivores highly susceptible Omnivores intermediate level of resistance. 1/21/2013 84PowerPoint Presentation: Wild herbivores or domesticated animals usually septicaemic Ingestion of spores along with coarse vegetation. Trauma of the intestinal tract entry of the spores into the host. infection after inhalation rare Skin abrasions -malignant pustules. 1/21/2013 85PowerPoint Presentation: 1/21/2013 86 Sudden death in any herbivore should be treated with suspicion A veterinary officer summoned - examine the carcass without a post-mortem examinationPowerPoint Presentation: A blood slide taken for Gram or methylene blue staining. Under the Anthrax Order the animal must remain on the farm and be incinerated on site if found to be positive 1/21/2013 87PowerPoint Presentation: Deep burial in quicklime -alternative method of disposal but the spores remain viable for many years and may contaminate pasture and infect grazing animals. 1/21/2013 88Lab diagonosis: Lab diagonosis Specimens Swabs ,fluid or pus from pustules Sputum and blood 1/21/2013 89Lab diagnosis: Lab diagnosis Full developed malignant pustule difficult to swab Central necrotic area -poor yield. Fluid aspirated from the surrounding vesicles, more likely to yield anthrax bacilli. Specimens taken before antibiotic therapy Clinical diagnosis easy -characteristic appearance and occupational exposure 1/21/2013 90microscopy: microscopy Gram's stain may show typical large Gram-positive bacill Indian ink- capsule appears as clear halo 1/21/2013 91culture: culture blood agar -large, flat, greyish colonies with the characteristic 'medusa head' appearance. Staining -colonies shows long chains of Gram-positive bacilli, some containing spores. Demonstration of non-motility, gelatin liquefaction, growth in straight chains and enhanced growth aerobically, as seen in the characteristic inverted fir tree appearance in a gelatin stab, will generally identify B. anthracis completely. 1/21/2013 92PowerPoint Presentation: 1/21/2013 93PowerPoint Presentation: Serological diagnosis - ELISA –done retrospectively-seldom used diagnostically. Polymerase chain reaction- rapid identification and diagnosis B. anthracis -a number of unique genes, the selection of suitable gene targets not problematic. Toxin production can be demonstrated by immunological or gene probe methods in reference laboratories. 1/21/2013 94B.Anthracis colonies lysis by gamma phage: B.Anthracis colonies lysis by gamma phage 1/21/2013 95Environmental samples: Environmental samples occasionally necessary to isolate B. anthracis from potentially contaminated material such as animal hair, hides or soil. The heat treatment of aqueous extracts of these materials at 60°C for 1 h kills all except spore-forming bacteria and fungi. For some soil types selective agars have been developed that allow preferential growth of B. anthracis 1/21/2013 96TREATMENT: TREATMENT . Penicillin remains the drug of choice, as β- lactamase -producing strains of B. anthracis are rare. .Most strains sensitive to macrolides , aminoglycosides , tetracyclines and chloramphenicol . .Ciprofloxacin prophylaxis or early treatment for greatest risk of exposure 1/21/2013 97prophylaxis: prophylaxis General methods-improvement of factory hygeine and proper sterilisation of animal products Animals given single dose sterne vaccine-1 yr protection 1/21/2013 98PowerPoint Presentation: The anthrax vaccine - culture filtrates of an avirulent , nonencapsulated strain known as V770-NP1-R. No living organisms are present in the vaccine December 2008, the new BioThrax IM Intramuscular injections in the deltoid 0 and 4 weeks and then at 6, 12, and 18 months, followed by annual boosters. Contains aluminium hydroxide as an adjuvant 1/21/2013 99PowerPoint Presentation: Prolonged initialization sequence is required with annual booster shots Anthrax vaccine's primary ingredient Anthrax Protective Antigen Can impair the life-cycle of the human immune systems memory B-Cells Memory T-cells through inducing the production of immunoglobulin G ( IgG ) which sequesters furin 1/21/2013 100Anthrax bioterrorism: Anthrax bioterrorism The possibility of creating aerosols containing anthrax spores has made B. anthracis a chosen weapon of bioterrorism. Iraq, Russia and as many as ten nations have the capability to load spores of B. anthracis into weapons. . 1/21/2013 101PowerPoint Presentation: 1/21/2013 102ANTHRACOID BACILLI: ANTHRACOID BACILLI Aerobic spore bearing bacilli similar- B.anthracis Some are frequent lab contaminants B.subtilis opportunistic pathogen Eye infections Septicemia 1/21/2013 103BACILLUS CEREUS : BACILLUS CEREUS Large Gram-positive bacillus Resembles B. Anthracis Motile and lacks the glutamic acid capsule Saprophyte Soil water vegetation 1/21/2013 104PowerPoint Presentation: B. cereus closely resembles B. anthracis in culture Forming large, grey, irregular colonies described as anthracoid 1/21/2013 105PowerPoint Presentation: Large inocula injected into laboratory animals may cause death Without the haemorrhagic appearance of anthrax Blood smears do not show the characteristic pink capsule with McFadyean's stain 1/21/2013 106PATHOGENESIS: PATHOGENESIS B. cereus is most commonly associated with food poisoning The organism can also cause post-traumatic ophthalmitis , which requires rapid, aggressive management locally 1/21/2013 107PowerPoint Presentation: An atypical strain capable of causing a disease that resembled inhalation anthrax has been described This strain appears to have acquired the toxin-encoding pX01 plasmid, and a plasmid encoding a polysaccharide capsule 1/21/2013 108PowerPoint Presentation: The capsule has the same role as the poly- d - glutamic acid capsule on the surface of B. anthracis Preliminary animal studies suggest that the strain is as virulent as B. Anthracis 1/21/2013 109Bacillus cereus: Bacillus cereus Cause of food poisoning Seen in Soil Vegetables Milk Cereals Spices meat poultry 1/21/2013 110Food poisoning: Food poisoning Spores of B. cereus are heat-resistant most strains produce toxins. The organism is widespread in the environment and is found in most raw foods, especially cereals such as rice. Enormous numbers of organisms (up to 10 10 organisms/g) may be found in contaminated food (commonly lightly cooked Chinese dishes), leading to two types of food poisoning: 1/21/2013 111PowerPoint Presentation: vomiting, occurring within 6 h of ingestion rice 1,3,5 It is caused by preformed toxin- lowmolecular weight, heat- and acid-stable peptide withstand intestinal proteolytic enzymes. 1/21/2013 112PowerPoint Presentation: A diarrhoeal form, occurring 8-24 h after ingestion 2,6,8,9,10,12 similar to enteritis caused by Escherichia coli or Salmonella enterica serotypes. caused by enterotoxins - like the Clostridium perfringens enterotoxin are heat labile formed in the intestine. 1/21/2013 113LABORATORY DIAGNOSIS: LABORATORY DIAGNOSIS food poisoning,-laboratory confirmation is easy if suspect food available for testing. 10 8 organisms/g -make the diagnosis in the absence of other food-poisoning bacteria. Anthracoid colonies on blood agar - B. cereus . Food reference laboratories are able to confirm identification and type if necessary. 1/21/2013 114PowerPoint Presentation: Methods for the laboratory identification of B. cereus strains that cause an inhalation anthrax-like disease have yet to be devised. It is likely that genetic tests will be effective in identifying these atypical strains. 1/21/2013 115TREATMENT: TREATMENT Emetic and diarrhoeal syndromes short lived No specific treatment is needed. Acute symptoms last less than 24 h and recovery on a reduced diet and fluids is rapid. antibiotic regimens for anthrax would be equally effective for the treatment of disease caused by atypical strains of B. cereus strains. 1/21/2013 116CONTROL: CONTROL Food poisoning caused by B. cereus is easily prevented by proper cooling and storage of food. Ideally, all dishes should be freshly prepared and eaten. Rice, in particular, should not be stored for long periods above 10°C. 1/21/2013 117STERILIZATION TEST BACILLI: STERILIZATION TEST BACILLI Bacillus stearothermophilus was, until the discovery of archaebacteria in hot springs, the most heat-resistant organism known. spores withstand 121°C for up to 12 min testing autoclaves to ensure the destruction of spores 1/21/2013 118PowerPoint Presentation: Strips containing B. stearothermophilus are included with the material being autoclaved Subsequently examined by culture for surviving spores The organism grows only at raised temperatures, between 50°C and 60°C; there is hardly any growth below 40°C 1/21/2013 119PowerPoint Presentation: Bacillus globigi , a red-pigmented variant of B. subtilis , has been used to test ethylene oxide sterilizers B. pumilus has been used to test the efficacy of ionizing radiation 1/21/2013 120 You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.