SOP on Preservation and Maintenance of Microorganisms
1.0 Purpose: This SOP describe a procedure for preservation and maintenance of microorganisms.
2.0 Scope: Sub-culture maintains and conserves all the characteristics of the microorganisms.
3.0 Responsibility: Quality Control Microbiologist to ensure that the procedure is followed.
4.0 Materials and Equipment: As required
5.0 Procedure:
5.1 Cultures of bacteria are maintained in tubes of media in which they have been cultivated by periodic transfers to fresh media.
5.2 The time intervals at which the transfer are made vary with the type of organisms.
5.3 By means of transfer loop, a portion of bacterial specimen is placed on the surface of a solid medium and streaked or spread over the surface.
5.4 This manipulation thins out the bacteria on the agar surface so that individual bacteria are separated from each other.
5.5 Agar slant cultures are prepared by making a streak inoculation up the middle of the slopped surface with a transfer needle.
5.6 For the stab cultures, the transfer needle carrying the inoculum is introduced in a straight line from the top to the bottom of the tube and removed along the same path.
5.7 Tubes of broth can be inoculated with the transfer loop.
5.8 A portion of a colony transferred to a tube of medium becomes a pure culture.
5.9 After appropriate incubation, growth from each culture should be checked microscopically to verify that it is a pure culture.