Bacterial Genotype Strains

EXPERIMENT 2: GENOTYPE OF STRAINS

Aim: To determine the genotypes of unknown bacterial strains

Method:

-We were provided with five unknown bacterial strains which we were to determine their genotypes.

-Also provided were nine agar plates containing different media, labeled A to J which had the presence or absence of known amino acids.

-Each of the nine plates was divided into five so as to be able to inoculate the five different strains on each plate using the sterile technique.

-Plates A, B and J were incubated at 37oC for 24 hours whilst plates C to H were incubated at 37oC for 48 hours.

Results/Observations

There was growth seen for all inoculated strains on plate A and they produced white colonies. This was expected since it was the complete medium. There was no growth for CSH 61, CSH 62 and CSH 63 in plate B and it contained streptomycin which is an antibiotic. The strains that grew produced white colonies in this case they were CHS 50 and CSH 54.

The plates from C to H were minimal media which had additions of different amino acids and nutrients, so each of the strains grew differently dependant on the medium. This is highlighted by the results obtained in the table on the next page.

For plate J which was the MacConkey agar, there were cream colonies for strains CSH 50 and CSH 54 whilst CSH 61, CSH 62 and CSH 63 produced pink colonies.

Table 1 below shows the results of the experiment:

Plate | CSH 50 | CSH 54 | CSH 61 | CSH 62 | CSH 63 |

A | ++ | + + | + + | + + | + + |

B | ++ | + + | - | - | - |

C | - | - | + + | + + | + + |

D | - | - | + + | + + | + + |

E | + | + | + + | + + | + + |

F | + | - | + + | + + | + + |

G | + | - | + + | + + | + + |

H | - | - | + + | + + | + + |

J | - (cream) | - (cream) | + + (pink) | + + (pink) | + + (pink) |

Table 1: The table shows the growth/no growth of the different strains on the different plates

The strains have the following genotypes (based on the results of the experiment):

CSH 50...