Question

50. What bacteria does MacConkey media select against?

51. Name 3 methods of isolating bacteria from a mixed culture.

52. What kind of mutation results from ultraviolet light exposure?

53. Name 2 methods bacteria can reverse the effect of UV light.

54. Which type of hemolysis produces a clear zone around the colony?

55. Is Salmonella a coliform?

56. Is Enterobacter a coliform?

57. What does the acronym IMVC stand for when testing the Enterobacteriaceae?

58. Name the one tube test that enable 15 tests of the Enterobacteriaceae.

59. Can nigrosin stain bacteria? What kind of staining can it be used for?

Answer 1

As per guidelines i answer first 4 questions.

1) MacConkey agar is mainly use for the isolation of gram negative Enteric bacteria. It is also used for differentiate Lactose fermenting and non lactose fermenting. Eg: Estiritia coli

It is a selective medium for the gram negative bacteria and also it inhibits the growth of gram positive bacteria. Eg: Staphylococci

2) the techniques used for the isolation of bacterias frone mixed cultures are the streak plate method , pour plate method and spread plate method

3) the uv radiation cause two Distinct mutations that are dimerizing mutation and oxidative mutations. It also cause for cancer in body cells

4) the bactria can be reverse the effect of uv light by photoreactivation. It is the direct reversal of damage by a photolayers.

Nucleotide excision repair also do the reversal.