Question

1) If you were going to redo this lab, what environments would you sample and why? 2) What criteria did you use to determine whether colonies are from the same or different bacteria? 3) Draw 4 test tubes – one has a pellicle, one has sediment, one has flocculent growth, and one has a pellicle and sediment.

Answer 1

1) Step 1: Inspect first the environmental conditions of the lab to grow the microbes which is the important factor to redo the lab

Reason: Bacteria grow in vast conditions; though they can adapt to the environment only certain temperature promote their growth while other will deteriorate the growth. These environmental conditions are the temperature, humidity, pH.

Step 2: Take a sampling in and around your place and study what kind of microbes will grow in a culture medium plate (Petri plate) based on the conditions mentioned above.

Step 3: Take samples as much as you can from all corners of the places to ensure that your not missing any important sampling.

Step 4: Prepare the plate and take precautions to avoid any cross contamination and streak the sampling you have taken from all the places, incubate at appropriate temperature to check the growth and carry out the experiement process.   

2) The criteria used to identify the colonies are based on the characteristics of the colony formation which is called as colony morphology. The 3 key characteristics are a) shape, b) color (pigmentation they form) and c) size. By clearly identifying and studying the key characteristics one can easily differentiate whether the colonies are from same or different bacteria.

For eg) based on the pigment formation: Green pigment produced by Pseudomonas aeruginosa and rough, dry colonies of Mycobacterium tuberculosis in Lowenstein-Jensen medium

Apart from the above mentioned key characteristics there are others uniqueness to identify the microbes in a colony are based on the a) Elevation they form in the culture b) Surface appearance c) Opacity (whether they are clear or not) d) Odor f) Consistency

3)Representative image of Bacterial Growth in Nutrient Broth