Sporulating cells

The uptake of Ca2+ by sporulating cells is of interest as it involves the reversal of the normal distribution of calcium between the intracellular compartment and the external medium. It is not... 

Bacillus thuringiensis Protein crystalline inclusions within sporulating cells... 

The Provesteen process, developed by Phillips Petroleum Company, employs a proprietary 25,000-L continuous fermentor for producing Hansenu/a jejunii the sporulating form of C. utilis from glucose or sucrose at high cell concentrations up to 150 g/L. The fermentor is designed to provide optimum oxygen and heat transfer (69,70). 

Some mycehal fermentations exhibit early sporulation, breakup of mycehum, and low yields if the shear is excessive. A tip speed or 250 to 500 cm/s (8 to 16 ft/s) is considered permissible. Mixing time has been proposed as a scale-up consideration, but httle can be done to improve it in a large fermenter because gigantic motors would be required to get rapid mixing. Culturing cells from plants or animals is beset by mixing problems because these cell are easily damaged by shear. 

Bacillus thuringiensis produces a variety of organic compounds which are toxic to the larvae of certain susceptible insect hosts. Among the toxic entities are proteinaceous crystals, probably three soluble toxins, and certain enzymes. The protein material is the major toxin active in killing lepidopterous larvae. The protein is formed by the cells apparently in close synchrony with sporulation, and its nature is a constant function of bacterial strain. The mode of action of the protein is under study. The sequence of events in the pathology observed is probably solubilization of the crystal (enzymatic or physical)—>liberation of toxic unit—>alteration of permeability of larval gut wall— change in hemolymph pH—>invasion of hemolymph by spores or vegetative cells of the bacterium. 

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... 

Cell Death. Spontaneous death or sporulation of cells is commonly modeled as a first-order process. Equation (12.8) (or 12.12)) is modified to include a disappearance term ... 

Fig. 2.6 The moqjhological events of sporulation in Saccharomyces cerevisiae. (a) starved cell V, vacuole LG, lipid granule ER, endoplasmic reticulum CW, cell wall M, mitochondrion S, spindle pole SM, spindle microtubules N, nucleus NO, nucleolus, (b) Synaptonemal complex (SX) and development of polycomplex body (PB) along with division of spindle pole body in (c). (d) First meiotic division which is completed in (e). (f) Prepararation for meiosis II. (g) Enlargement of prospore wall, culminating in enclosure of separate haploid nuclei (h). (i) Spore coat (SC) materials produced and deposited, giving rise to the distinct outer spore coat (OSC) seen in the completed spores of the mature ascus (j). Reproduced from the review by Dickinson (1988) with permission from Blackwell Science Ltd.

The bulk of evidence indicates the existence of a close relationship between spore formation and the exhaustion of nutrients essential for continued vegetative growth. Sporulation is a defense mechanism to protect the cell when the occasion arises. 

Spore formation is limited almost entirely to two genera of rodshaped bacteria Bacillus (aerobic or facultatively anaerobic), and Clostridium (anaerobic or aerotolerant). With one possible exception, the common spherical bacteria do not sporulate. Some spore-bearing species can be made to lose their ability to produce spores. When the ability to produce spores is once lost, it is seldom regained. SporMation is not a process to increase bacterial numbers because a cell rarely produces more than one spore. 

The conditions which have been reported as favoring sporulation include addition of salts of metals such as manganese, chromium, nickel, etc., to the medium shaking a culture of vegetative cells of sporing aerobes with distilled water at 37°C. addition of tomato juice to a medium incubating the cultures at an appropriate temperature addition of calcium carbonate to a carbohydrate medium to prevent excessive accumulation of acid, and to maintain the pH at 5.5 or above the necessity yeen addition to the medium of certain amino acids etc. 

PHAs are synthesized as intracellular energy and carbon storage materials. Therefore, bacterial cells with a high content of poly(3HB) are better able to survive than cells with a low poly(3HB) content [15]. Poly(3HB) also serves as an endogenous carbon and energy source for sporulation in Bacillus species and cyst formation in Azobacter species [16-18] and the majority of bacteria investigated accumulate PHAs in response to a nutrient limitation. The reported... 

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