Spores, bacterial

When considering how the evolution of life could have come about, the seeding of terrestrial life by extraterrestrial bacterial spores traveling through space (panspermia) deserves mention. Much is said about the possibility of some form of life on other planets, including Mars or more distant celestial bodies. Is it possible for some remnants of bacterial life, enclosed in a protective coat of rock dust, to have traveled enormous distances, staying dormant at the extremely low temperature of space and even surviving deadly radiation The spore may be neither alive nor completely dead, and even after billions of years it could have an infinitesimal chance to reach a planet where liquid water could restart its life. Is this science fiction or a real possibility We don t know. Around the turn of the twentieth century Svante Arrhenius (Nobel Prize in chemistry 1903) developed this theory in more detail. There was much recent excitement about claimed fossil bacterial remains in a Martian meteorite recovered from Antarctica (not since... 

Sporicide kills (inactivates) bacterial spores, and is therefore expected to kill all other microorganisms of less resistance. According to the AO AC International it may not kill 100% of the spores, and therefore may not be as powerful as a sterilant. However, according to the EPA, sporicide and sterilant are considered identical. 

Lysol consists of a mixture of the three cresol isomers solubilized using a soap prepared from linseed oil and potassium hydroxide, to form a clear solution on dilution. Most vegetative pathogens, including mycobacteria, are killed in 15 minutes by 0.3—0.6% lysol. Lysol has a phenol coefficient of 2. Bacterial spores are very resistant. Lysol is also the name of a proprietary product, the formula of which has changed over the years other phenols have been substituted for the cresols. 

At 70—140°C, peroxide is vaporised. Peroxide vapor has been reported to rapidly inactivate pathogenic bacteria, yeast, and bacterial spores in very low concentrations (133). Experiments using peroxide vapor for space decontamination of rooms and biologic safety cabinets hold promise (134). The use of peroxide vapor and a plasma generated by radio frequency energy releasing free radicals, ions, excited atoms, and excited molecules in a sterilising chamber has been patented (135). 

Ethylene oxide is able to inactivate all microorganisms. Bacterial spores are more resistant than vegetative cells, yeasts, and molds (287). Spores are 5 to 10 times more resistant than the vegetative cells (288). bacillus subtilis spores were the most resistant of those tested (289). Ethylene oxide was also shown to be vimcidal (290). 

Sterilization of Media First-order kinetics may be assumed for heat destruction of living matter, and this leads to a linear relationship when logarithm of the fraction surviving is plotted against time. However, nonlogarithmic kinetics of death are quite often found for bacterial spores. One model for such behavior assumes inactivation of spores via a sensitive intermediate state by the mechanism ... 

FIG. 24-19 Typical death-rate data for bacterial spores (B. stearother-mophilus). To convert to F, multiply hy 1.8 and add 32 (Wang et ah, Fermentation and Enzyme Technology, Wiley-lntersdence, New York, 1979, p. 140.)... 

Relative thermal resistance for the different types of microorganisms encountered in typical environments associated with fermentation broths is shown in Table 24-3. Bacterial spores are far more resistant to moist heat than are any other type oi microbial contaminants thus, a sterilization cycle based on the destruction of bacterial spores should destroy all life. 

The bacterial culture converts a portion of the supplied nutrient into vegetative cells, spores, crystalline protein toxin, soluble toxins, exoenzymes, and metabolic excretion products by the time of complete sporulation of the population. Although synchronous growth is not necessary, nearly simultaneous sporulation of the entire population is desired in order to obtain a uniform product. Depending on the manner of recovery of active material for the product, it will contain the insolubles including bacterial spores, crystals, cellular debris, and residual medium ingredients plus any soluble materials which may be carried with the fluid constituents. Diluents, vehicles, stickers, and chemical protectants, as the individual formulation procedure may dictate, are then added to the harvested fermentation products. The materials are used experimentally and commercially as dusts, wettable powders, and sprayable liquid formulations. Thus, a... 

Bradbury, J.H., Foster, J.R., Hammer, B., Lindsay, J. Murrell, W.G. (1981). The source of heat resistance of bacterial spores. Study of water in spores by NMR. Biochimica Biophysica Acta, 678, 157-64. 

Ross, K.F.A. Billing, E. (1957). The water and solid content of living bacterial spores and vegetative cells as indicated by refractive index measurements. Journal of General Microbiology, 17, 418-25. 

The existence and possible presence of bacterial spores determines the parameters, i.e. time and temperature relationships, of thermal sterilization processes which are used extensively by the food and pharmaceutical industry. These are defined below (see also Chapters 20 and 23). 

Due to a waxy component in the cell wall these organisms are difficult to stain with ordinary stain solutions, the hydrophobic nature of the wall being stain repellent however, if the bacterial smear on the slide is warmed with the stain, the cells are dyed so strongly that they are not decolorized by washing with dilute acid, hence the term acid-fast. Many bacterial spores exhibit the phenomenon of acid fastness. 

Gould G.W. (1985) Modification of resistance and dormancy. In Fundamental and Applied Aspects of Bacterial Spores (eds G. J. Dring, D. J. Ellar G.W. Gould), pp. 371-382. London Academic Press. 

Russell A.D. (1982) The Destruction of Bacterial Spores. London Academic Press. 

Microorganisms surviving M. tuberculosis Bacterial spores HBV and prions as in Creutzfeldt-Jakob disease Bacterial spores Prions Extreme challenge of resistant bacterial spores Prions (insufficient data)... 

Bacterial spores are the most resistant of all microbial forms to chemical treatment. The majority of antimicrobial agents have no useful sporicidal action, with the exception of the aldehydes, halogens and peroxygen compounds. Such chemicals are sometimes used as an alternative to physical methods for sterilization ofheat sensitive equipment. In these circumstances, correct usage of the agent is of paramount importance since safety margins are lower in comparison with physical methods of sterilization (Chapter 20). 

Russell A.D. (1990) Bacterial spores and chemical sporicidal agents. Clin Microbiol Rev, 3, 99-119. Russell A.D. (1996) Activity of biocides ogidn X mycoh CtQno.. JApplBacteriol Symp Suppl, 81, 87S-lOlS. 

Mycobacteria are more resistant than other non-sporulating bacteria to a wide range of biocides. Examples of such organisms axe Mycobacterium tuberculosis, theM avium-intracellulare (MAI) group andM. chelonae (M. chelonei). Of the bacteria, however, the most resistant of all to biocides are bacterial spores, e.g. Bacillus subtilis, B. cereus. 

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