Question

1. why it is recommended to culture Staphylococcus aureus in a Blood Agar medium? in short answer

2. During testing bacteria in water exercise, forming a bubble in the test tube is an indication of what happening?

3.Turing sucrose, glucose and lactose tube of unknown bacteria from red to yellow is an indication of what?

Answer 1

1, Staphylococcus aureus is a fastidious organism that can be grown only with extra nutritional supplements. MSA, Blood agar, chocolate agar are commonly used for S aureus.

the blood agar supplemented with sheep s erythrocytes is a rich medium where the beta-hemolytic property of S aureus can be seen and differentiated. It helps for easy identification of the bacteria based on the colony characters such as beta hemolysis with the pigmented colony (golden yellow). They can be easily grown in blood agar media.

2, Bubble formation while testing the bacteria for water quality analysis indicates that the bacteria are capable of fermenting the sugar and producing gas, bubbles indicate gas production

3, The fermentation test of lactose, sucrose and glucose by unknown bacteria is done in the media which consists of these sugars and an acid-base indicator mostly phenol red. On fermenting the sugars, acid end products are produced. SO the neutral pH of the media changed into an acidic medium which is indicated by yellow colour of the phenol red. so the change of media from red to yellow indicates that acid is produced and the bacteria is capable of fermentation of the particular sugar.