Homework Soursea You decide to separate the bio and X strain from the mix Y
a. You decide to separate the bio- and X strain from the mix. You have spreaders, filter paper, Petri plates with agar gels supplemented with either biotin, only arginine, both or none (minimal medium), and an incubator. How would you proceed?
b. During your work under point a. above to recover your precious bio- strain, you discover an F- strain with wild-type genotype (bio+ arg+) that has emerged from the mixing of the two strains. How could you notice the bio+arg+ genotype during the rescue operation?
c. What is the most likely genotype of the strain X?
Solution
a). To separate the bio- and X strain from the mix.
We would spread the mixture of strains on biotin + Arginine plates at different dilutions. Following the growth of the colonies, we shall pick up individual colonies and make master plates on all the plates (i.e., on the biotin, arginine, both arginine and biotin and on the minimal medium plates).
The colonies growing in the presence of biotin plate will be selected and recovered as bio- strain.
Similarly, the colonies growing on arginine plates will be recovered as X strain
b). The bio+arg+ genotype can be noticed due to the growth on the minimal media.
c). The genotype of X strain is
Arg- bio+
