(f) Aseptic technique and cell culture

• Aseptic technique eliminates unwanted microbial contaminants when culturing micro-organisms or cells

  • Aseptic technique involves the sterilisation of equipment and culture media by heat or chemical means and subsequent exclusion of microbial contaminants.

• A microbial culture can be started using an inoculum of microbial cells on an agar medium, or in a broth with suitable nutrients

  • Many culture media exist that promote the growth of specific types of cells and microbes.

• Animal cells are grown in medium containing growth factors from serum

  • Growth factors are proteins that promote cell growth and proliferation. 

  • Growth factors are essential for the culture of most animal cells.

• In culture, primary cell lines can divide a limited number of times, whereas tumour cells lines can perform unlimited divisions

• Plating out of a liquid microbial culture on solid media allows the number of colony-forming units to be counted and the density of cells in the culture estimated

• Serial dilution is often needed to achieve a suitable colony count

• Method and use of haemocytometer to estimate cell numbers in a liquid culture

• Vital staining is required to identify and count viable cells