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perfringens outbreaks occur most often in November and December. Outbreaks tend to happen in places that serve large groups of people, such as hospitals, school cafeterias, prisons, and nursing homes, and at events with catered food. perfringens infection include meat, poultry, gravies, and other foods cooked in large batches and held at an unsafe temperature. After someone swallows the bacteria, it can produce a toxin (poison) that causes diarrhea.Ĭommon sources of C. Under certain conditions, such as when food is kept at an unsafe temperature external icon (between 40☏–140☏), C. These bacteria make spores, which act like protective coatings that help the bacteria survive. perfringens can be found on raw meat and poultry, in the intestines of animals, and in the environment. CDC estimates these bacteria cause nearly 1 million illnesses in the United States every year.Ĭ. 1959 Dec 6:483–498.Clostridium perfringens bacteria are one of the most common causes of foodborne illness (food poisoning). Spore and parasporal protein formation in Bacillus cereus var. Chemical and morphological studies of bacterial spore formation.
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Application of solutions containing lead and barium. Staining of tissue sections for electron microscopy with heavy metals. Observations on the nucleus of resting and germinating spores of Bacillus megaterium. Biochemical changes occurring during sporulation in Bacillus species. Biochemical changes occurring during the germination of bacterial spores. Vegetative and mature phage DNA as compared with normal bacterial nucleoids in different physiological states. Electron microscope study of DNA-containing plasms. An effective method of preparing sections of Bacillus polymyxa sporangia and spores for electron microscopy. Development of fine structure, thermostability, and dipicolinate during sporogenesis in a bacillus. Structure and nucleic acid content of spores. Comparison of species and yarieties of the genus Bacillus. A simplified method of staining thin sections of biolgical material with lead hydroxide for electron microscopy. Electron microscope observations on the behavior of the bacterial cytoplasmic membrane during cellular division. Calcium reversal of the heat susceptibility and dipicolinate deficiency of spores formed "endotrophically" in water. This may not be the complete list of references from this article.
#Spore formation pdf
The Full Text of this article is available as a PDF (1.5M). Unlike ripe spores, they do not react violently to acid hydrolysis and, in thin sections, their cytoplasmic granules continue to stain with lead solutions.
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The resulting deficient spores are liberated from the sporangia but are unstable in water suspensions. If calcium is withheld during the period of uptake beyond a critical point, sporulating cells lose the ability to assimilate calcium and to form normal amounts of dipicolinic acid. In calcium-deficient media, final refractility is lessened and dipicolinic acid is formed only in amounts proportional to the available calcium. With this whitening, calcium uptake commences, closely followed by the synthesis of dipicolinic acid and the process is terminated, an hour later, with the formation of a fully refractile spore. As these latter layers appear, the spores, previously dense by dark phase contrast, gradually "whiten" or show an increase in refractive index. Then when the cortex is ⅓ fully formed, the spore coat and exosporium are laid down peripheral to the outer membrane layer covering the cortex. First, the cortex is laid down between the recently described (5) double layers of the forespore membrane. Particular attention was paid to the development of the three spore layers-cortex, coat, and exosporium-in relation to the forespore membrane.
#Spore formation free
From the stage of a completed membranous forespore to that of a fully ripened free spore, synchronously sporulating cells of a variant Bacillus cereus were studied by cytological and chemical methods.