![]() Gram-positive or Gram-negative? The cell wall structure of endospore-forming bacteria is consistent with that of Gram-positive bacteria, and young cultures stain as expected. Aerial distribution of the dormant spores probably explains the occurrence of aerobic sporeformers in most habitats examined.īacillus coagulans. Gram stain. Endospore formation, universally found in the group, is thought to be a strategy for survival in the soil environment, wherein these bacteria predominate. Their collective features include degradation of most all substrates derived from plant and animal sources, including cellulose, starch, pectin, proteins, agar, hydrocarbons, and others antibiotic production nitrification denitrification nitrogen fixation facultative lithotrophy autotrophy acidophily alkaliphily psychrophily thermophily and parasitism. There is great diversity of physiology among the aerobic sporeformers, not surprising considering their recently-discovered phylogenetic diversity. ![]() The ubiquity and diversity of these bacteria in nature, the unusual resistance of their endospores to chemical and physical agents, the developmental cycle of endospore formation, the production of antibiotics, the toxicity of their spores and protein crystals for many insects, and the pathogen Bacillus anthracis, have attracted ongoing interest in these bacteria since and Cohn and Koch’s discoveries in the 1870s. The trivial name assigned to them is aerobic sporeformers. The unifying characteristic of these bacteria is that they are Gram-positive, formendospores, and grow in the presence of O 2. In order to accommodate former members of the genus Bacilluscovered in this chapter, its title has been changed to “Gram-positive aerobic or facultative endospore-forming bacteria”. The genus Bacillus remained intact until 2004, when it was split into several families and genera of endospore-forming bacteria, justifiable on the basis of ssRNA analysis. He was able to recover the original anthrax organism from the dead mouse, demonstrating for the first time that a specific bacterium is the cause of a specific disease. ![]() He took a small amount of blood from such an animal and injected it into a healthy mouse, which subsequently became diseased and died. ![]() Robert Koch’s original photomicrographs of Bacillus anthracis. In 1876, Koch established by careful microscopy that the bacterium was always present in the blood of animals that died of anthrax. Koch relied on Cohn’s observations in his classic work (1876), The etiology of anthrax based on the life history of Bacillus anthracis, which provided the first proof that a specific microorganism could cause a specific disease. The organism represented what was to become a large and diverse genus of bacteria named Bacillus, in the Family Bacillaceae. In 1872, Ferdinand Cohn, a contemporary of Robert Koch, recognized and named the bacterium Bacillus subtilis. The organism is Gram-positive, capable ofgrowth in the presence of oxygen, and forms a unique type of resting cell called an endospore. Gram-positive, Aerobic or Facultative Endospore-forming Bacteria
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