tailieunhanh - Laboratory Exercises in Microbiology - part 3

Vi sinh vật được chuyển từ một môi trường nuôi cấy khác bằng cách cấy truyền, bằng cách sử dụng các thủ tục cụ thể và kỹ thuật vô trùng. (Vô trùng có nghĩa là miễn phí từ nhiễm trùng huyết kỹ thuật vô trùng này có tầm quan trọng như vậy mà nó sẽ được sử dụng trong [một điều kiện độc hại là hệ quả từ sự hiện diện của vi sinh vật.] | Harley-Prescott Laboratory Exercises in Microbiology Fifth Edition III. Basic Laboratory and Culture Techniques 14. Culture Transfer Instru. Techniques Isolat. Maint. of Pure Cultures The McGraw-Hill Companies 2002 Figure Microbiological Transfer Instruments. a Inoculating needle and b inoculating loop. ------Handle Shaft. Needle Loop----o a b flame from a Bunsen burner or into a Bacti-Cinerator see figure . When done correctly all parts of the wire will turn red with heat. The needle or loop should then be used before it becomes contaminated. After you have finished using an inoculating loop or needle it should be thoroughly flame-sterilized. Microorganisms are transferred from one culture medium to another by subculturing using specific procedures and aseptic technique. Asepsis means free from sepsis a toxic condition resulting from the presence of microorganisms. This aseptic technique is of such importance that it will be used in most of the exercises in this manual. Since microorganisms are always present in the laboratory if aseptic technique is not followed there is a good possibility that external contamination will result and will interfere with the results. Proper aseptic technique also protects the laboratory worker from contamination with the culture. Principles for Isolation of Pure Cultures and Their Maintenance Once discrete well-separated colonies develop on the surface of the streak plate selected ones may be picked up with an inoculating needle and transferred to separate culture tubes such as tryptic soy agar slants the type of agar will depend on the microorganism . Where possible bacteria from the center of a colony are transferred because the center is less likely to be contaminated than the edges. Each slant now represents the growth of a single species of microorganism and is called a pure or stock culture. One of the more important problems in a microbiology laboratory is the maintenance of pure stock cultures over a long period.