Hygiene

Good personal hygiene and hygienic approaches to food preparation and storage are essential to our good health. The open-ended protocol 'Investigating antimicrobial action' shows how to evaluate the antimicrobial products of any personal or domestic hygiene product.

Find out more about how microbes develop as frozen food thaws and demonstrate the risk of re-freezing any foodstuff.

Experiments

• How good is your toilet paper?
  Use the harmless yeast Saccharomyces cerevisiae to simulate contamination of hands with faecal microbes and the effectiveness of hand washing in removing them.
• Investigating anti-microbial action
  A technique for investigating anti-microbial action that students can use to test hypotheses about disinfectants, personal hygiene products or plant extracts.
• Standard technique: Making serial dilutions
  Instructions for students, for making a series of dilutions of any substance.
• Standard technique: Maintaining and preparing cultures of bacteria and yeasts
  Notes on maintaining stock cultures, and preparing actively growing cultures for use by students.
• Standard technique: Making a streak plate
  In a streak plate of an inoculum of bacteria or yeast the inoculum should be progressively diluted to the point where cells are sufficiently separated that you can see single isolated colonies after incubation.
• Standard technique: Making a spread or ‘lawn’ plate
  This method makes an even confluent growth of culture on which you can test the sensitivity of bacteria to antimicrobial substances, or carry out quantitative work with suitable dilutions of inoculum.
• Standard technique: Making up nutrient agars
  Details of how to make up different culture media for culturing different microorganisms.
• Standard technique: Making a pour plate
  A small amount of inoculum from a broth culture grows in a dish of medium. Determine a viable count per cm³ if the dilution produces 30-100 separate countable colonies.