Dried bacterial cells

Suspend dried bacterial cells (500 mg), which have been ground with a mortar and pestle, in 15 mL of 10 mAf Tris-Cl buffer (pH 8.0), containing 2% SDS, 4% 2-mercaptoethanol, and 2 mAf MgCl2. Vortex the mixture and place it in a 65 °C water bath until the bacterial cells are solubilized. Occasional vortexing may be necessary during the heating process. 

Aphanothece sacrum (Suizenji-nori) is an edible cyanobacterium that is indigenous to Japan. The dried bacterial cells are commonly used as a food... 

The direct microscopic count determines the number of viable and dead microorganisms ia a milk sample. A small amount (0.01 mL) of milk is spread over a 1.0 cm area on a microscope sHde and allowed to dry. After staining with an appropriate dye, usually methylene blue, the sHde is examined with the aid of a microscope (oil immersion lens). The number of bacterial cells and clumps of cells per microscopic field is determined and, by appropriate calculations, is expressed as the number of organisms per milliliter of sample. 

Salt preserves foods by providing a hostile environment for certain microorganisms. Within foods, salt brine dehydrates bacterial cells, alters osmotic pressure, and inhibits bacterial growth and subsequent spoilage. Dry salt and salt brine are used in several types of curing processes. Pickles are preserved in strong brine before final processing. 

The harvest is a very eomplex mixture of bacterial cells, metabolic products and exhausted medium. In the ease of a live attenuated vaccine it is innocuous and all that is necessary is for the baeteria to be separated and resuspended in an appropriate menstmum, possibly for freeze-drying. In a vaccine made Irom a pathogen the harvest may be intensely dangerous and great care is necessary in the following procedures. 

Fractionation. The process by which components are extracted firm bacterial eells or from the medium in whieh the baeteria are grown and obtained in a purified form. The polysaccharide antigens of Neisseria meningitidis are separated from the bacterial cells by treatment with hexadecyltrimethylammonium bromide and those of Streptococcus pneumoniae with ethanol. The purity of an extracted material may be improved by resolubilization in a suitable solvent and precipitation. After purification, a component may be dried to a powder, stored indefinitely and, as required, incorporated into a vaccine in precisely weighed amounts at the blending stage. 

Biological samples such as bacteria and viruses have been studied by SdFFF as well as FIFFF. These two techniques provided bacterial number, density, size, and mass distributions of bacterial cells of diverse shapes and sizes, molecular weights, sizes, densities, and diffusivities of viruses. SdFFF has been used to analyze protein particles, including casein derived from nonfat dry milk, albumin microspheres, and particles in cataractous lenses originating from the aggregation of lens proteins. 

Since bacterial cells weigh about 0.3 pg dry weight per cell (Madigan et al., 2000) and their dry mass is about 50% carbon, this yield appears reasonable (i.e., about 60 g of cells from 100 g of p-cresol). 

Heat is the most widely used means of sterilization, which can be employed for both liquid medium and heatable solid objects. It can be applied as dry or moist heat (steam). The moist heat is more effective than the dry heat, because the intrinsic heat resistance of vegetative bacterial cells is greatly increased in a completely dry state. As a result the death rate is much lower for the dry cells than for moist ones. The heat conduction in dry air is also less rapid than in steam. Therefore, dry heat is used only for the sterilization of glassware or heatable solid materials. By pressurizing a vessel, the steam temperature can be increased significantly above the boiling point of water. Laboratory autoclaves are commonly operated at a steam pressure of about 30 psia, which corresponds to 121°C. Even bacterial spores are rapidly killed at 121 °C. 

H. Protective effect of organic and related compounds on bacterial cells during freeze-drying. Agric. Biol. Chem. 29, 61-65,1965... 

Assuming 100% recovery of the cellular DNA and assuming the wet bacterial cell paste was 80% water, calculate the percent of the dry weight in the bacterial cells that is DNA. How do your results agree with the DNA content of a typical bacterium, which is about 3% of the cell s dry weight If your results do not agree with this value, discuss possible reasons for the discrepancy. 

The stability of freeze-dried bacteria depends on the duration of incubation prior to freeze-drying, i.e., the condition of the bacterial cell [8-11]. The same holds true for viruses. Canine distemper virus, for example, shows some delicacy upon... 

Freund and Stone have studied the production of allergic encephalomyelitis and aspermatogenesis, and have found that 7 to 10 times more wax D than dried, whole, tubercle bacilli was required for inducing these allergic states. They think that these observations are not in favor of the role of wax D as an adjuvant the results of Freund and Stone are, however, easily explained by the above-mentioned hypothesis that both the bacterial cell-walls and the wax D of human strains are active, because of the common general chemical structure the cell walls have, of course, a much greater surface than the wax D, in paraffin oil, and can thus be more active. 

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