Question

1) Why is it important not to touch previous streaks when making your forth streak for SCL.

2) What assumption is made regarding all the cell of a colony?

3) In addition to physical characteristics, what other information is needed when describing colony morphology?

4) How does colony morphology help you monitor to purify of your culture?

5) how does a colony counter aid in describing morphology?

Answer 1

1, Generally we do not touch any of the previous streaks while performing streak plate method. The purpose of streaking is to decrease the bacterial load gradually and end up in singe pure colony by the last streaks. so when we touch the previous streak while doing the present streak, we will not get isolated colonies and the bacterial load would not have decreased.

2, While viewing the cell of a colony, we can assume that all the cells from one single colony is of a particular or a single bacterium. Cells clump together forming a single colony by binary fission. So we can predict if its a pure culture or mixed culture.

3, In addition to physical characteristics such as size, shape and texture of bacterial colonies, other information such as incubation time period, temperature, type of media used, oxygen requirements provided, source of bacterial sample are provided.

4, Colony morphology can help us monitor if the culture is pure or mixed. Pure culture is the growth of bacterial colonies with same type of morphology. All the colonies look alike under a colony counter when the culture is pure. When the size, shape, colour, texture, elevation,edges of all the colonies of a plate are alike, we cell them a pure culture i.e., all the cells has arisen from binary fission of a single bacterium which has clumped up into a colonies.

5, The light transmission and the magnifying glasses in the colony counter zooms the bacterial culture in a plate. Since it is zoomed in, we can find any small differences in the colony morphology rather than viewing in the naked eye. So it helps in defining each and every structure of colony morphology of an agar plate