II.Coccobacilli Bacillus Thuringiensis is a Gram-positive, soil-dwelling bacterium, commonly used as a pesticide. Additionally, B. thuringiensis also occurs naturally in the gut of caterpillars of various types of moths and butterflies, as well as on the dark surface of plants. Bordetella is a genus of small (0.2 - 0.7 µm), Gram-negative coccobacilli of the phylum proteobacteria. Bordetella species, with the exception of B. petrii, are obligate aerobes as well as highly fastidious, or difficult to culture. Three species are human pathogens (B. pertussis, B. parapertussis, B. bronchiseptica); one of these (B. bronchiseptica) is also motile III. Irregular Rods Clostridium tetani is an anaerobic bacterium of the genus Clostridium. Like other Clostridium species, it is Gram-positive, and its appearance on a gram stain resembles tennis rackets or drumsticks.C. tetani is found as spores in soil or as parasites in the gastrointestinal tract of animals. C. tetani produces a potent biological toxin, tetanospasmin, and is the causative agent of tetanus. IV. Filamentous Rods Bacteroides biacutis is a genus of Gram-negative, bacillus bacteria. Bacteroides species are non-endospore-forming, anaerobes, and may be either motile or non-motile, depending on the species. The DNA base composition is 40-48% GC. Unusual in bacterial organisms, Bacteroides membranes contain sphingolipids. They also contain mesodiaminopimelic acid in their peptidoglycan layer. Nocardia is a genus of weakly-staining Gram-positive, catalase-positive, rod-shaped bacteria. It forms partially acidfast beaded branching filaments (acting as fungi, but being truly bacteria). It has total 85 species. Some species are non pathogenic; some species are pathogenic (nocardiosis). Nocardia are found worldwide in soil that is rich with organic matter. Most Nocardia infections are acquired by inhalation of the bacteria or through traumatic introduction. V. Palisades Arrangement Corynebacterium diphtheriae is a pathogenic bacterium that causes diphtheria. It is also known as the Klebs-Löffler bacillus, because it was discovered in 1884 by German bacteriologists Edwin Klebs (1834 – 1912) and Friedrich Löffler (1852 – 1915). VI. Spore – Forming Rods Bacillus stearothermophilus (or Geobacillus stearothermophilus) is a rod-shaped, Grampositive bacterium and a member of the division Firmicutes. The bacteria is a thermophile and is widely distributed in soil, hot springs, ocean sediment, and is a cause of spoilage in food products. It will grow within a temperature range of 30-75 degrees celsius. It is commonly used as a challenge organism for sterilization validation studies and periodic check of sterilization cycles. Coxiella burnetii is a species of intracellular, pathogenic bacteria, and is the causative agent of Q fever. The genus Coxiella is morphologically similar to Rickettsia, but with a variety of genetic and physiological differences. C. burnetii are small Gram negative bacteria with two growth phases, as well as a spore form which lies idle in soil.[1] It can survive standard disinfectants, and is resistant to many other environmental changes like those presented in the phagolysosome.