Bacterial filters

Bacterial filters - the adaptations, allowing to separate the microorganisms that are visible in the optical microscope, from the liquid environment in which they are located.
Bacterial filters used for sterilization of solutions that changes its properties after heat sterilization (serum, medicinal substances, nutrient). Filtering using bacterial filters can be carried out in vacuum or under pressure. However, the sharp vacuum or excessively high pressure violate the quality filtration and lead to the violation of sterility. The pore size of sterilizing bacterial filters should not exceed 750 MMK. There are the following types of bacterial filters : candles of Chamberlan1) ceramic [candles of Chamberlin (Fig. 1) or Berkefeld]; filter material in these bacterial filters is kaolin with a mixture of quartz or infusoria land, subjected to the firing; 2) glass filters (Fig. 2) - Buchner funnel with soldered plate of fine glass; 3) allodynia plate filters prepared from the nitrocellulose or acetate (in particular, filters Elford). In the USSR issued allodynia filters with a diameter of 35 mm, for use in the filter apparatus of Seitz (Fig. 3)filter apparatus of Seitz, in which the filtering is performed through special asbestos plates.
Material to filter must be cleaned of coarse elements by pre-filtration paper filters or centrifugation at low speeds (2000 - 4000 rpm). Solutions containing a high concentration of protein, before being filtered, it is advisable to breed. When using ceramic filters, it is advisable to first fill the filter with the environment, which contains a suspension of bacteria.
Ceramic and glass bacterial filters after using restore by cleaning and sterilization. Removal of organic residues bacterial filters warm up in a muffle furnace (heat is transferred through the walls of the camera, which is heated bacterial filter.
Ceramic bacterial filters to filter sterilized in an autoclave at temperature 120 degrees for 15-30 minutes, then washed in warm water, weak solution of formalin and 15% solution of bleach. Thus treated ceramic biological filters. Washed in tap water and distilled water and dried. Glass biological filters purified by filtration through them diluted acids, washed in water, and then distilled water and sterilized in a drying case at temperature of 105 degrees. Allodynia plate biological filters are sterilized by boiling for 20 minutes Used allodynia biological filters do not recover.