How does refrigeration limit microbial growth?  What effect does extreme temperature (hot and cold) have on the enzymes involved in cellular metabolism, growth and development?

‘Chance favors the prepared mind.’ -Louis Pasteur (1822-1895).

Prior to the 1859, it was a commonly held view that life arises from non-living matter.  This was a long held view until a series of experiments (Fig.1) by Louis Pasteur disproved this notion of Spontaneous Generation and gave way for the theory of Biogenesis.  Biogenesis states that all life forms arise from pre-existing life forms through reproduction.  This finding was revolutionary at the time and the research techniques used are still in practice today (i.e., Pasteurized milk, cheese, yogurt, etc.).

Advanced refrigeration and heating practices allow food to be stored for extended periods of time without spoiling.  Canning practices provide an extended shelf-life for certain ‘non-perishable’ foods.  There are recommended temperatures for cooking certain types of meat and and pickling is an effective way to preserve a wide range of foods.  The questions are why and how?

For this weeks Discussion Forum, we will explore some of the questions surrounding cellular growth and reproduction, food spoilage and disease.  Please discuss each of the points below.

1) What is pasteurization and how does it improve the shelf-life of select foods without effecting the nutritional value of the food? Provide an example.

2) How does refrigeration limit microbial growth?  What effect does extreme temperature (hot and cold) have on the enzymes involved in cellular metabolism, growth and development?

3) How does pH effect enzyme activity?  Why do specific enzymes have specific pH ranges that they can tolerate in different parts of our bodies (Fig.2)? Provide one example of an enzyme, its function in humans and the pH range in which it operates.

4) What do hyperthermophiles (Fig.3a) have to do with DNA fingerprinting (Fig. 3b)? Briefly explain.

(Fig.2) 

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