WEEK 10

BMY3201-1 BASIC MICROBIOLOGY TECHNIQUES
WHAT HAVE I LEARN?

We continue experiment for Part 4 on the physical factors on the microbial growth, that is Experiment 14, Physical Factors: Temperature and Experiment 15: Physical factors: pH of the Extracellular Environment. 

Microbial growth is directly dependent on the temperature. If the temperature is extreme high, this will cause the cellular enzyme of microbes lose its three dimensional shape, thus lead to denaturation of protein. However when the temperature is lowered towards freezing point, the cellular enzyme at this state is inactive, cellular metabolism become slower. Bacteria are capable in growing at range of -5°C to 80°C. Bacteria can be classify also based on their temperature requirement. Psychrophiles are bacterial species which grow range of -5°C to 20°C, mesophiles grow 20°C to 45°C, they have ability to grow on human body which are at 37°C. Thermophiles can withstand temperature 35°C and above. Facultative thermophiles grow at 37°C, optimum for 45°C to 60°C while obligate thermophiles with only grow above 50°C, optimum growth will be above 60°C. However the optimum growth of microbes is not necessary to be the best temperature for the production of pigmentation. o bacterial growth, pigment production or gas production  is shown at 4°C in the refrigerator. When come to 20°C of room temperature, pigment, bacterial growth can be seen for S. marcescens, P. aruginosa and E. coli. The bacterial growth and production of pigment and gas can also be observed at 37°C of body temperature. No other bacterial growth and pigment production can be seen at 60°C, only B. stearithermophilus show growth. 

Pigmentation produced by S. marcescens at 20°C

Production of gas from Saccharomyces cerevisiae happen at 37°C